Deformable liposomes as enhancer of caffeine penetration through human skin in a Franz diffusion cell test.

OBJECTIVE: The permeation of hydrophilic molecules through the skin is still a challenge due to the barrier posed by stratum corneum, the outermost layer of the skin. Liposomes have frequently been used as carriers for different types of drugs and may also function as permeation enhancers. Propylene glycol has also been used as an edge activator in liposomes to increase the permeation. The aim of this work was to prepare liposomes containing an edge activator and loaded with caffeine to evaluate the potential of caffeine reaching the deeper layers in the skin. METHODS: The formulations were prepared by a top-down process using high-pressure homogenization at 200 00 psi for 10 min. They were characterized by size, polydispersity index (PI), zeta potential (ZP), pH, caffeine content and encapsulation efficiency (EE%) on preparation (time zero) and after 30 days. Cytotoxicity of blank and loaded liposomes was assessed by MTT proliferation assay with a normal keratinocyte cell line (HaCaT). In vitro permeation tests were performed with human skin in Franz cells over 24 h, and caffeine concentration was determined in the skin surface, stratum corneum, dermo-epidermal fraction and receptor medium by HPLC. RESULTS: The caffeine liposomes with (DL-Caf) or without propylene glycol (CL-Caf) showed, respectively, mean size 94.5 and 95.4 nm, PI 0.48 and 0.42, ZP + 1.3 and + 18.1 mV and caffeine content of 78.57 and 80.13%. IC50 values of caffeine in DL-Caf (3.59 v/v %) and CL-Caf (3.65 v/v %) were not significantly different from conventional blank liposome (3.27 v/v %). The DL-Caf formulation presented the best capability to enhance the caffeine permeation through the skin, resulting 1.94-folds higher than caffeine solution. Furthermore, the caffeine flux from DL-Caf was 1.56- and 3.05-folds higher than caffeine solution and CL-Caf, respectively. On the other hand, CL-Caf showed the lowest caffeine penetration revealing the importance of edge activator to aid hydrophilic drug penetration to all skin layers. CONCLUSION: The DL-Caf formulation tested was able to improve the permeation of caffeine through the stratum corneum and dermo-epidermal layers, suggesting that this delivery system may be effective for deep skin delivery of hydrophilic drugs.

OBJECTIF: La perm´eation de mol´ecules hydrophiles `a travers lapeau reste un d´efi en raison de la barri`ere oppos´ee par la couchecorn´ee, la couche la plus externe de la peau. Les liposomes ontfr´equemment ´et´e utilis´es comme supports pour diff´erents types dem´edicaments et peuvent ´egalement fonctionner comme des amplificateursde perm´eation. Le propyl`ene glycol a ´egalement ´et´e utilis´ecomme activateur dans les liposomes pour augmenter la perm´eation.Le but de ce travail ´etait de pr´eparer des liposomes contenantun activateur et charg´es de caf´eine pour ´evaluer le potentiel de lacaf´eine atteignant les couches les plus profondes de la peau. MÉTHODES: Les formulations sont pr´epar´ees par homog´en´eisationhaute pression `a 200 00 psi pendant 10 min. Elles sontcaract´eris´es par la taille des liposomes, l'indice de polydispersit´e(PI), le potentiel zˆeta (ZP), le pH, la teneur en caf´eine et l'efficacit´ed'encapsulation (EE%) `a la pr´eparation (temps z´ero) et apr`es 30jours. La cytotoxicit´e des liposomes `a blanc et charg´es est ´evalu´eepar un test de prolif´eration MTT avec une lign´ee cellulaire de k´eratinocytesnormale (HaCaT). Des tests de perm´eation in vitro sontr´ealis´es avec de la peau humaine dans des cellules de Franz pendant24 h, et la concentration de caf´eine est d´etermin´ee `a la surfacede la peau, dans la couche corn´ee, la fraction dermo-´epidermique et le milieu r´ecepteur par HPLC. RÉSULTATS: Les liposomes contenant de la caf´eine avec (DL-Caf)ou sans propyl`ene glycol (CL-Caf) pr´esentent respectivement unetaille moyenne de 94,5 et 95,4 nm, PI 0,48 et 0,42, ZP + 1,3 et +18,1 mV et une teneur en caf´eine de 78,57 et 80,13%. Les valeursIC50 de la caf´eine dans DL - Caf (3,59 %v/v) et CL - Caf (3,65 %v/v) ne sont pas significativement diff´erentes de celles du liposome `ablanc conventionnel (3,27 %v/v). La formulation DL-Caf est cellequi permet la meilleure perm´eation de la caf´eine, avec une quantit´ede caf´eine dans la peau 1,94 fois plus ´elev´ee que la solution decaf´eine. De plus, le flux de caf´eine de DL-Caf est 1,56 et 3,05 foisplus ´elev´e que la solution de caf´eine et CL-Caf, respectivement.D'autre part, CL-Caf montre la plus faible p´en´etration de caf´eine,r´ev´elant l'importance de l'activateur pour aider `a la p´en´etration dela mol´ecule hydrophile dans toutes les couches de la peau. CONCLUSION: La formulation DL-Caf test´ee am´eliore la perm´eationde la caf´eine `a travers la couche corn´ee et les couches dermo-´epidermiques, ce qui sugg`ere que ce syst`eme d'administration peutˆetre efficace pour l'administration cutan´ee profonde de mol´eculeshydrophiles.

Topical insulin in neurotrophic keratopathy after resection of acoustic neuroma. / Insulina tópica en queratopatía neurotrófica tras resección de neurinoma del acústico.

CASE REPORT: A patient with a history of surgical resection of an acoustic neuroma presented with involvement of both the left facial nerve and the left trigeminal nerve. She initially consulted for exposure keratitis, but two weeks later presented with an infectious keratitis. After taking the corneal sample, she presented with persistent epithelial defect, which did not respond to medical management. Topical insulin was indicated, and a decrease in the area of the lesion was seen in the following 5 days. A therapeutic contact lens was also placed at that time and finally, two weeks after the initiation of insulin, the epithelial defect completely closed. DISCUSSION: This was a complex case due to the confluence of facial paralysis, neurotrophic keratitis, and infectious keratitis, which finally had a successful outcome. Topical insulin can be an effective adjuvant therapy in cases of neurotrophic ulcers that do not respond to standard therapy.

Compartmental modeling of skin transport.

The primary objective of this study is to introduce a simple and flexible mathematical approach which models transport processes in skin using compartments. The main feature of the presented approach is that the rate constants for exchange between compartments are derived from physiologically relevant diffusional transport parameters. This allows for better physical interpretation of the rate constants, and limits the number of parameters for the compartmental model. The resulting compartmental solution is in good agreement with previously published solutions for the diffusion model of skin when ten or more compartments are used. It was found that the new compartmental model with three compartments provided a better fit of the previously publish water penetration data than the diffusion model. Two special cases for which it is difficult to implement the diffusion model were considered using our compartmental approach. In both cases the compartmental model predictions agreed well with the diffusion model.

Topical and cutaneous delivery using nanosystems.

The goal of topical and cutaneous delivery is to deliver therapeutic and other substances to a desired target site in the skin at appropriate doses to achieve a safe and efficacious outcome. Normally, however, when the stratum corneum is intact and the skin barrier is uncompromised, this is limited to molecules that are relatively lipophilic, small and uncharged, thereby excluding many potentially useful therapeutic peptides, proteins, vaccines, gene fragments or drug-carrying particles. In this review we will describe how nanosystems are being increasingly exploited for topical and cutaneous delivery, particularly for these previously difficult substances. This is also being driven by the development of novel technologies, which include minimally invasive delivery systems and more precise fabrication techniques. While there is a vast array of nanosystems under development and many undergoing advanced clinical trials, relatively few have achieved full translation to clinical practice. This slow uptake may be due, in part, to the need for a rigorous demonstration of safety in these new nanotechnologies. Some of the safety aspects associated with nanosystems will be considered in this review.

Technical Note: A new phantom design for routine testing of Doppler ultrasound.

PURPOSE: The objective of this project is to demonstrate the principle and operation for a simple, inexpensive, and highly portable Doppler ultrasound quality assurance (QA) phantom intended for routine QA testing. A prototype phantom has been designed, fabricated, and evaluated. The phantom described here is powered by gravity alone, requires no external equipment for operation, and produces a stable fluid velocity useful for quality assurance. Many commercially available Doppler ultrasound testing systems can suffer from issues such as a lengthy setup, prohibitive cost, nonportable size, or difficulty in use. This new phantom design aims to address some of these problems and create a phantom appropriate for assessing Doppler ultrasound stability. METHODS: The phantom was fabricated using a 3D printer. The basic design of the phantom is to provide gravity-powered flow of a Doppler fluid between two reservoirs. The printed components were connected with latex tubing and then seated in a tissue mimicking gel. Spectral Doppler waveforms were sampled to evaluate variations in the data, and the phantom was evaluated using high frame rate video to find an alternate measure of mean fluid velocity flowing in the phantom. RESULTS: The current system design maintains stable flow from one reservoir to the other for approximately 7 s. Color Doppler imaging of the phantom was found to be qualitatively consistent with laminar flow. Using pulsed spectral Doppler, the average fluid velocity from a sample volume approximately centered in the synthetic vessel was measured to be 56 cm/s with a standard deviation of 3.2 cm/s across 118 measurements. An independent measure of the average fluid velocity was measured to be 51.9 cm/s with a standard deviation of 0.7 cm/s over 4 measurements. CONCLUSIONS: The developed phantom provides stable fluid flow useful for frequent clinical Doppler ultrasound testing and attempts to address several obstacles facing Doppler phantom testing. Such an ultrasound phantom can make routine testing more approachable for institutions that wish to initiate a Doppler QA program or complement a previously existing QA program.

Human skin penetration and local effects of topical nano zinc oxide after occlusion and barrier impairment.

Public health concerns continue to exist over the safety of zinc oxide nanoparticles that are commonly used in sunscreen formulations. In this work, we assessed the effects of two conditions which may be encountered in everyday sunscreen use, occlusion and a compromised skin barrier, on the penetration and local toxicity of two topically applied zinc oxide nanoparticle products. Caprylic/capric triglyceride (CCT) suspensions of commercially used zinc oxide nanoparticles, either uncoated or with a silane coating, were applied to intact and barrier impaired skin of volunteers, without and with occlusion for a period of six hours. The exposure time was chosen to simulate normal in-use conditions. Multiphoton tomography with fluorescence lifetime imaging was used to noninvasively assess zinc oxide penetration and cellular metabolic changes that could be indicative of toxicity. We found that zinc oxide nanoparticles did not penetrate into the viable epidermis of intact or barrier impaired skin of volunteers, without or with occlusion. We also observed no apparent toxicity in the viable epidermis below the application sites. These findings were validated by ex vivo human skin studies in which zinc penetration was assessed by multiphoton tomography with fluorescence lifetime imaging as well as Zinpyr-1 staining and toxicity was assessed by MTS assays in zinc oxide treated skin cryosections. In conclusion, applications of zinc oxide nanoparticles under occlusive in-use conditions to volunteers are not associated with any measurable zinc oxide penetration into, or local toxicity in the viable epidermis below the application site.

Measurement of compartment elasticity using pressure related ultrasound: a method to identify patients with potential compartment syndrome.

PURPOSE OF THE STUDY Decision-making in treatment of an acute compartment syndrome is based on clinical assessment, supported by invasive monitoring. Thus, evolving compartment syndrome may require repeated pressure measurements. In suspected cases of potential compartment syndromes clinical assessment alone seems to be unreliable. The objective of this study was to investigate the feasibility of a non-invasive application estimating whole compartmental elasticity by ultrasound, which may improve accuracy of diagnostics. MATERIAL AND METHODS In an in-vitro model, using an artificial container simulating dimensions of the human anterior tibial compartment, intracompartmental pressures (p) were raised subsequently up to 80 mm Hg by infusion of saline solution. The compartmental depth (mm) in the cross-section view was measured before and after manual probe compression (100 mm Hg) upon the surface resulting in a linear compartmental displacement (Δd). This was repeated at rising compartmental pressures. The resulting displacements were related to the corresponding intra-compartmental pressures simulated in our model. A hypothesized relationship between pressures related compartmental displacement and the elasticity at elevated compartment pressures was investigated. RESULTS With rising compartmental pressures, a non-linear, reciprocal proportional relation between the displacement (mm) and the intra-compartmental pressure (mm Hg) occurred. The Pearson's coefficient showed a high correlation (r2 = -0.960). The intraobserver reliability value kappa resulted in a statistically high reliability (κ = 0.840). The inter-observer value indicated a fair reliability (κ = 0.640). CONCLUSIONS Our model reveals that a strong correlation between compartmental strain displacements assessed by ultrasound and the intra-compartmental pressure changes occurs. Further studies are required to prove whether this assessment is transferable to human muscle tissue. Determining the complete compartmental elasticity by ultrasound enhancement, this application may improve detection of early signs of potential compartment syndrome. Key words: compartment syndrome, intra-compartmental pressure, non-invasive diagnostic, elasticity measurement, elastography.

Walleye Sander vitreus (Mitchill) are relatively resistant to experimental infection with VHSV IVb and extant walleye strains vary in susceptibility.

Compared to fathead minnow, walleye demonstrate low susceptibility to experimental infection with VHSV IVb, regardless of route of exposure or water temperature at time of infection. In triplicate and duplicate groups, walleye were intraperitoneally (i.p.) injected (102 -108  pfu/fish) or waterborne-exposed (w; 1.4 × 107  pfu mL-1 ) with VHSV IVb. High cumulative mortality (64-100%) and severe gross lesions associated with VHSV IVb infection were evident only in fish i.p. injected with 108  pfu at 12 °C. These fish had multifocal necrosis of several tissues including the gill and heart. There was no difference in mortality between walleye infected (w or i.p.) at 12 °C (spring stocking) compared with a declining temperature profile from 18 to 12 °C (fall stocking). There were significant differences (P < 0.05) in mortality between four extant walleye strains following i.p. infection, indicating that the choice of walleye strain for stocking might be an important consideration. Viral antigen was found in both i.p. and w-exposed walleye using immunohistochemistry, mostly within the gill and skin of w-exposed fish and most prominently in dermal fibrocytes. VHSV IVb was detected in multiple tissues from 6 to 21 days post-infection using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR).

Second-order statistics and 'designer' waves for violent free-surface motion around multi-column structures.

Extreme wave-structure interactions are investigated using second-order diffraction theory. The statistics of surface elevation around a multi-column structure are collected using Monte Carlo-type simulations for severe sea states. Within the footprint of a realistic four-column structure, we find that the presence of the structure can give rise to extreme crest elevations greater than twice those at the same return period in the incident wave field. Much of this extra elevation is associated with the excitation of second-order near-trapped modes. A 'designer' incident wave can be defined at each point around the structure for a given sea state as the average input wave to produce extreme crest elevations at a given return period, and we show that this wave can be simply vertically scaled to estimate the response at other return periods.

Analysing the skin barrier from down under.

Over the past 40 years the Australian contribution to the field of skin science has been led by Michael Roberts. One of his earliest papers on membrane permeation was published in Nature, setting the scene for his huge contribution to both the fundamental understanding of skin permeability and the application of that knowledge to improved clinical outcomes, new delivery technologies and minimizing toxicological risk. His work has been characterized by a mechanistic, mathematical approach to defining skin permeation. He defined the parameters important to skin permeation, established structure-penetration relationships and demonstrated the importance of maximum flux from a clinical and toxicological viewpoint. Through his systematic approach, Mike showed a parabolic relationship between maximum flux and lipophilicity, and established that this is driven mainly by variations in solubility of the solute in the stratum corneum. One of the significant strengths of Mike's work is the ability to express biological concepts in mathematical terms. He has developed mathematical models that enhance our understanding of epidermal, dermal, deep tissue permeation and follicular transport. Throughout his career Mike has been involved in pioneering new technologies both for analysing the skin barrier and influencing permeation across it. His fundamental work in the area of iontophoresis provided models that defined the parameters influencing its permeation enhancement. Mike's research has been translated into improved clinical outcomes, reduced toxicological risk and changes to the regulation of skin products. This article provides an insight into Mike Roberts and the Australian contribution to skin science.

Iontophoresis-mediated transdermal permeation of peptide dendrimers across human epidermis.

PURPOSE OF THE STUDY: The overall aim of the present work was to elucidate the effects of iontophoresis on assisting permeation/deposition of peptide dendrimers across/within human skin. PROCEDURES: A series of peptide dendrimers containing arginine and histidine as terminal acids were synthesized and characterized. These dendrimers were subjected to passive and iontophoretic permeation studies across human epidermis. RESULTS: The synthesized peptide dendrimers were found to be stable in epidermal, dermal and skin extracts up to 6 h. Passive diffusion studies revealed that none of the synthesized peptide dendrimers permeated human epidermis up to 6 h, although minute concentrations of low molecular weight dendrimers were detected in receptor medium at the end of 24 h. Application of iontophoresis significantly increased the permeation of all the tested peptide dendrimers across human skin in a molecular weight-dependent manner compared to simple passive diffusion. Electromigration was found to be the dominant mechanism behind the iontophoretic permeation of peptide dendrimers across human skin. CONCLUSIONS: The present study demonstrates that iontophoresis is an effective technique in enhancing the transdermal permeation of peptide dendrimers. MESSAGE OF THE PAPER: This study foresees the possibility of applying peptide dendrimers in iontophoretic delivery of drugs and macromolecules across/within the skin.

Mortality following hip fracture: trends and geographical variations over the last 40 years.

Hip fractures are an ever increasing cause of morbidity and mortality. Treatment of this condition requires an all-encompassing approach from prevention to post-operative care. It is important in such a situation to gather data on the incidence and trends of hip fractures to aid in the future treatment planning of this important condition. A review of all articles published on the outcome after hip fracture over a four decade period (1959-1998) was undertaken to determine any changes that had occurred in the demographics of patients and mortality over this time period. The mean age of patients sustaining hip fractures was found to be steadily increasing over the study period at a rate of 1 year of age for every 5-year time period. The mean age in the 1960s was 73 years to a mean of 79 years in the 1990s. No notable differences were seen in the proportion of male patients over the years but a definite downward trend was noticed with regard to intracapsular fractures. The mortality at 6 and 12 months after injury remained essentially unchanged over the four decades reviewed. Mortality after a hip fracture remains significant, being 11-23% at 6 months and 22-29% at 1 year from injury. Geographical variations exist in the mortality after hip fracture. More detailed international comparisons are required to determine if these differences in outcome are accounted for by the variations in the demographics of patients or due to diversities in treatment methods.

Association between chronic fatigue syndrome and the corticosteroid-binding globulin gene ALA SER224 polymorphism.

Chronic fatigue syndrome (CFS) is characterized by idiopathic fatigue of greater than 6 months' duration with postexertional exacerbation and many other symptoms. A trend toward relative hypocortisolism is described in CFS. Twin and family studies indicate a substantial genetic etiologic component to CFS. Recently, severe corticosteroid-binding globulin (CBG) gene mutations have been associated with CFS in isolated kindreds. Human leukocyte elastase, an enzyme important in CBG catabolism at inflammatory sites, is reported to be elevated in CFS. We hypothesized that CBG gene polymorphisms may act as a genetic risk factor for CFS. A total of 248 patients with CFS defined by Centers for Disease Control criteria, and 248 controls were recruited. Sequencing and restriction enzyme testing of the CBG gene coding region allowed detection of severe CBG gene mutations and a common exon 3 polymorphism (c.825G-->T, Ala-Ser224). Plasma CBG levels were measured in 125 CFS patients and 198 controls by radioimmunoassay. Total and free (calculated and measured) cortisol levels were ascertained in single samples between 8-10 a.m. The age of onset (mid 30s) and gender ratio (2.2:1, female:male) of the patients were similar to those reported in U.S. epidemiologic studies. A trend toward a preponderance of serine224 homozygosity among the CFS patients was noted, compared with controls (chi2 = 5.31, P = 0.07). Immunoreactive-CBG (IR-CBG) levels were higher in Serine/Alanine (Ser/Ala) than Ala/Ala subjects and higher again in Ser/Ser subjects, this effect was strongest in controls; Ser/Ser: 46.1+/-1.8 (n = 31, P = 0.03) vs. Ser/Ala: 42.4+/-1.0 (n = 56, P = 0.05) vs. Ala/Ala: 40.8+/-1.7 microg/mL (n = 21). Despite higher CBG levels, there was a nonsignificant trend toward lower total and free plasma cortisol in serine allele positive patients, total cortisol: Ser/Ser: 13.3+/-1.4 (n = 34) vs. Ser/Ala: 14.0+/-0.7 (n = 66) vs. Ala/Ala: 15.4+/-1.0 (n = 23). Homozygosity for the serine allele of the CBG gene may predispose to CFS, perhaps due to an effect on hypothalamic-pituitary-adrenal axis function related to altered CBG-cortisol transport function or immune-cortisol interactions.

Early rise in blood pressure following administration of adrenocorticotropic hormone-[1-24] in humans.

1. An elevation in blood pressure has been consistently observed 24 h after adrenocorticotropic hormone (ACTH) administration and is caused by increased ACTH-stimulated cortisol secretion, in association with increased cardiac output. The aim of the present study was to investigate the previously undefined time of onset of this increase in blood pressure in normal humans. 2. Ten normal healthy volunteers received 250 mg ACTH-[1-24], in 500 mL normal saline, infused at a constant rate over 8 h. Six subjects also received a placebo infusion (normal saline only). Blood pressure, heart rate and cortisol levels were determined hourly. Adrenocorticotropic hormone (ACTH-[1-24] plus native ACTH) was measured at 0, 1, 7 and 8 h. 3. Infusion of ACTH-[1-24] produced maximal secretion rates of cortisol, resulting in a mean peak plasma level of 985 +/- 46 nmol/L at 8 h. In response, blood pressure and heart rate rose significantly by 2 h and remained generally elevated for the duration of the infusion. 4. The early onset of haemodynamic responses is consistent with classical steroid receptor-mediated genomic mechanisms, but could be due non-genomic mechanisms. 5. The cardiovascular consequences of therapeutic use of ACTH are well recognized. This results of the present study suggest that even diagnostic administration of ACTH, delivered over a few hours, may raise blood pressure.

Familial corticosteroid-binding globulin deficiency due to a novel null mutation: association with fatigue and relative hypotension.

Corticosteroid-binding globulin is a 383-amino acid glycoprotein that serves a hormone transport role and may have functions related to the stress response and inflammation. We describe a 39-member Italian-Australian family with a novel complete loss of function (null) mutation of the corticosteroid-binding globulin gene. A second, previously described, mutation (Lyon) segregated independently in the same kindred. The novel exon 2 mutation led to a premature termination codon corresponding to residue -12 of the procorticosteroid-binding globulin molecule (c.121G-->A). Among 32 family members there were 3 null homozygotes, 19 null heterozygotes, 2 compound heterozygotes, 3 Lyon heterozygotes, and 5 individuals without corticosteroid-binding globulin mutations. Plasma immunoreactive corticosteroid-binding globulin was undetectable in null homozygotes, and mean corticosteroid-binding globulin levels were reduced by approximately 50% at 18.7 +/- 1.3 microg/ml (reference range, 30-52 microg/ml) in null heterozygotes. Morning total plasma cortisol levels were less than 1.8 microg/dl in homozygotes and were positively correlated to the plasma corticosteroid-binding globulin level in heterozygotes. Homozygotes and heterozygote null mutation subjects had a high prevalence of hypotension and fatigue. Among 19 adults with the null mutation, the systolic blood pressure z-score was 12.1 +/- 3.5; 11 of 19 subjects (54%) had a systolic blood pressure below the third percentile. The mean diastolic blood pressure z-score was 18.1 +/- 3.4; 8 of 19 subjects (42%) had a diastolic blood pressure z-score below 10. Idiopathic chronic fatigue was present in 12 of 14 adult null heterozygote subjects (86%) and in 2 of 3 null homozygotes. Five cases met the Centers for Disease Control criteria for chronic fatigue syndrome. Fatigue questionnaires revealed scores of 25.1 +/- 2.5 in 18 adults with the mutation vs. 4.2 +/- 1.5 in 23 healthy controls (P < 0.0001). Compound heterozygosity for both mutations resulted in plasma cortisol levels comparable to those in null homozygotes. Abnormal corticosteroid-binding globulin concentrations or binding affinity may lead to the misdiagnosis of isolated ACTH deficiency. The mechanism of the association between fatigue and relative hypotension is not established by these studies. As idiopathic fatigue disorders are associated with relatively low plasma cortisol, abnormalities of corticosteroid-binding globulin may be pathogenic.

The insulin hypoglycemia test: hypoglycemic criteria and reproducibility.

The insulin hypoglycemia test (IHT) is widely regarded as the "gold standard" for dynamic stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. This study aimed to investigate the temporal relationship between a rapid decrease in plasma glucose and the corresponding rise in plasma adenocorticotropic hormone (ACTH), and to assess the reproducibility of hormone responses to hypoglycemia in normal humans. Ten normal subjects underwent IHTs, using an insulin dose of 0.15 U/kg. Of these, eight had a second IHT (IHT2) and three went on to a third test (IHT3). Plasma ACTH and cortisol were measured at 15-min intervals and, additionally, in four IHT2s and the three IHT3s, ACTH was measured at 2.5- or 5-min intervals. Mean glucose nadirs and mean ACTH and cortisol responses were not significantly different between IHT1, IHT2 and IHT3. Combined data from all 21 tests showed the magnitude of the cortisol responses, but not the ACTH responses, correlated significantly with the depth and duration of hypoglycemia. All subjects achieved glucose concentrations of of < or = 1.6 mmol/l before any detectable rise in ACTH occurred. In the seven tests performed with frequent sampling, an ACTH rise never preceded the glucose nadir, but occurred at the nadir, or up to 15 min after. On repeat testing, peak ACTH levels varied markedly within individuals, whereas peak cortisol levels were more reproducible (mean coefficient of variation 7%). In conclusion, hypoglycemia of < or = 1.6 mmol/l was sufficient to cause stimulation of the HPA axis in all 21 IHTs conducted in normal subjects. Nonetheless, our data cannot reveal whether higher glucose nadirs would stimulate increased HPA axis activity in all subjects. Overall, the cortisol response to hypoglycemia is more reproducible than the ACTH response but, in an individual subject, the difference in peak cortisol between two IHTs may exceed 100 nmol/l.

Ethical beliefs of mental-health professionals and undergraduates regarding therapist practices.

Psychotherapists should be aware of any discrepancies of opinion between themselves and those outside the mental-health profession regarding the ethicality of therapist actions. In this study, the beliefs of mental-health professionals and nonprofessionals (represented by undergraduate students) regarding the ethicality of therapist behaviors were compared. Factor analysis of 82 specific therapist behaviors yielded three factors: nonsexual dual relationships, assertive or discomforting therapist actions, and sexual dual relationships. A comparison of factor composite scores indicated that undergraduates, in relation to professionals, rated nonsexual dual relationships as more ethical and assertive or discomforting actions as less ethical. Although these effects may diminish with age, these results nonetheless suggest that mental-health professionals may hold ethical beliefs that are inconsistent with those who seek their services. Implications of these findings are discussed.

A comparison of factor scores under conditions of factor obliquity.

Six different methods of computing factor scores were investigated in a simulation study. Population scores created from oblique factor patterns selected from the psychological literature served as the bases for the simulations, and the stability of the different methods was assessed through cross-validation in a subject-sampling model. Results from 5 evaluative criteria indicated that a simplified, unit-weighting procedure based on the factor score coefficients was generally superior to several unit-weighting procedures based on the pattern or structure coefficients. This simplified method of computing factor scores also compared favorably with an exact-weighting scheme based on the full factor score coefficient matrix. Results are discussed with regard to their potential impact on current practice, and several recommendations are offered.

Adrenocorticotropin stimulation tests in patients with hypothalamic-pituitary disease: low dose, standard high dose and 8-h infusion tests.

OBJECTIVES: Low doses of ACTH [1-24] (0.1, 0.5 and 1.0 microg per 1.73 m2) may provide a more physiological level of adrenal stimulation than the standard 250 microg test, but not all studies have concluded that the 1.0 microg is a more sensitive screening test for central hypoadrenalism. Eight-hour infusions of high dose ACTH [1-24] have also been suggested as a means of assessing the adrenals' capacity for sustained cortisol secretion. In this study, we compared the diagnostic accuracy of three low dose ACTH tests (LDTs) and the 8-h infusion with the standard 250 microg test (HDT) and the insulin hypoglycaemia test (IHT) in patients with hypothalamic-pituitary disease. SUBJECTS AND DESIGN: Three groups of subjects were studied. A healthy control group (group 1, n = 9) and 33 patients with known hypothalamic or pituitary disease who were divided into group 2 (n = 12, underwent IHT) and group 3 (n = 21, IHT contraindicated). Six different tests were performed: a standard IHT (0.15 U/kg soluble insulin); a 60-minute 250 microg HDT; three different LDTs using 0.1 microg, 0.5 microg and 1.0 microg (all per 1.73 m2); and an 8-h infusion test (250 microg ACTH [1-24] at a constant rate over 8 h). RESULTS: Nine out of the 12 patients in group 2 failed the IHT. Three out of 12 patients from group 2 who clearly passed the IHT, also passed all the ACTH [1-24] stimulation tests. Seven of the 9 patients who failed the IHT, failed by a clear margin (peak cortisol < 85% of the lowest normal). Two of the 7 also failed all the ACTH [1-24] tests. Five of the 7 patients had discordant results, four passed the 0.1 LDT, one (out of four) passed the 0.5 LDT, none (out of three) passed the 1.0 LDT, two passed the HDT and three passed the 8-h test. Two patients were regarded as borderline fails in the IHT. Both passed the ACTH [1-24] tests, although one was a borderline pass in the 8-h test. Only five out of the 21 patients in group 3 showed discordance between the HDT and the LDTs. One patient passed the HDT and failed the 0.1 LDT, four patients failed the HDT but passed some of the different LDTS. CONCLUSIONS: We conclude that in the diagnosis of central hypoadrenalism, ACTH [1-24] stimulation tests may give misleading results compared to the IHT. The use of low bolus doses of ACTH [1-24] (1.0, 0.5 or 0.1 microg) or a high dose prolonged infusion does not greatly improve the sensitivity of ACTH [1-24] testing. Dynamic tests that provide a central stimulus remain preferable in the assessment of patients with suspected ACTH deficiency.

Computing and evaluating factor scores.

A variety of methods for computing factor scores can be found in the psychological literature. These methods grew out of a historic debate regarding the indeterminate nature of the common factor model. Unfortunately, most researchers are unaware of the indeterminacy issue and the problems associated with a number of the factor scoring procedures. This article reviews the history and nature of factor score indeterminacy. Novel computer programs for assessing the degree of indeterminacy in a given analysis, as well as for computing and evaluating different types of factor scores, are then presented and demonstrated using data from the Wechsler Intelligence Scale for Children-Third Edition. It is argued that factor score indeterminacy should be routinely assessed and reported as part of any exploratory factor analysis and that factor scores should be thoroughly evaluated before they are reported or used in subsequent statistical analyses.