Activity-dependent refinement in the goldfish retinotectal system is mediated by the dynamic regulation of processes withdrawal: an in vivo imaging study.

Imaging of regenerating optic fibers in living adult goldfish was used to visualize arbor restructuring during activity-dependent refinement. A small number of neighboring retinal ganglion cells were labeled with DiI and observed in the tectum of the living animal for 5-7 hours during the period of activity-dependent refinement. In contrast to earlier stages of regeneration, many optic arbors were surprisingly stable, showing little or no change. The observed changes were mainly retractions, and these were affected by retinotopic position and activity. Axon branches in retinotopic positions changed by much smaller amounts than ectopic axons, but in fish with retinal tetrodotoxin impulse blockade, no systematic difference was observed as a function of tectal position. Otherwise, impulse blockade had no notable effects.

Characterization of the block structure and molecular weight of sodium alginates.

Sodium alginates are widely used within the pharmaceutical sciences, yet the molecular characteristics of these materials are frequently not stated. In this study, a range of characterization techniques is applied to five sodium alginate samples and the data compared, both between techniques and with the information obtained from the manufacturer. The mannuronic acid to guluronic acid (MG) ratio and the distribution of uronic acid residues of five sodium alginate samples have been measured using circular dichroism and NMR, with circular dichroism yielding MG ratios between 42.1 and 63.6%, depending on the grade of alginate used. The MG ratios obtained from NMR studies were in broad agreement with these values, and the technique also yielded information on the distribution of uronic acid residues within each batch; this was again found to vary considerably (NG > 1 values ranging from 6.9 to 17.5). It was noted that samples with similar MG ratios could have markedly different chain-distribution characteristics. The uronic acid ratio ranges obtained from the manufacturers were found to be in good agreement with those found experimentally. Intrinsic viscosity measurements were used to compare the molecular weights of the samples; values between approximately 12,000 and 180,000 were obtained for the different batches. The study has enabled comparison of different methods for characterization of sodium alginate samples, highlighting their relative merits and the possible protocols that might be adopted. A critical discussion is given of the individual and combined use of these techniques and the relevance of such studies to the rational design and quality control of alginate-based pharmaceutical systems.

Alternative psychotherapeutic practice among middle class Americans: II: Some conceptual and practical comparisons.

This article will contextualize ethnographic and clinical features that distinguish one particular alternative healing method (Self-Acceptance Training) from 'main-stream' psychotherapeutic procedures. Factors common to many psychotherapies are listed and a series of contrasts and comparisons made by examining definitions of: (1) presenting problems, (2) inciting events, (3) phasic development, (4) taxonomic classifications, (5) therapeutic interventions, and (6) prognostic formulations. The alternative method of treatment described in a companion publication ('SAT') is used to make some specific comparisons (Zatzick and Johnson 1997). Basch's (1980) concise recording of a dynamic therapy is borrowed for purposes of a comparative hypothetical treatment of his patient through a Self-Acceptance Training session. Some directions for future work are suggested.

Alternative psychotherapeutic practice among middle class Americans: I: Case studies and follow-up.

Historically, alternative psychotherapeutic procedures have florished worldwide in various inspirational, spiritualistic and shamanistic versions. However, few investigations have described these interventions in detail, or followed the clinical outcomes longitudinally. This present report is an ethnographic and clinical description of one particular American practitioner's alternative method as it is used with middle class clientele in several regions of the USA. Two case studies are presented in detail while nine individual cases are qualitatively reviewed with one month and one year treatment outcomes reported. A condensed ethnobiographical study of the practitioner's personal and professional life is included.

Childhood epilepsy in Papua New Guinea.

A prospective study of 40 children with epilepsy was carried out between June 1990 and August 1991 at Port Moresby General Hospital. Half of the children had yet to start school. Significant features in their past medical histories were acute meningitis (38%), tuberculous meningitis (10%), febrile convulsions (10%) and head trauma (5%). Most cases had grand mal epilepsy (80%). The majority of the children with epilepsy (90%) were treated with a single drug, which was usually phenobarbitone. 22% had received more than one drug, but not simultaneously. Significant side-effects requiring change of treatment occurred in 10%. Disturbed behaviour was reported in 55% and 22% had a poor social outcome. 45% had complete control of fits clinically. This study showed that in Port Moresby acute meningitis is a significant cause of epilepsy in young children, the majority of whom present with grand mal epilepsy, which is usually controlled by phenobarbitone, a readily available and cheap drug and still a useful anticonvulsant in the developing world.

Psychological distress among inner-city american elderly: Structural, developmental, and situational contexts.

This analysis explores the prevalence of psychological distress and the factors associated with its occurrence among 200 inner-city residents, 65% of whom are African Americans. Comparisons by gender and race find that women and African Americans are less likely to be distressed. Distress, however, is significantly associated with poorer health and fewer social and economic resources. A model depicting pathways to distress is used in a case study analysis of the most distressed respondents. It illustrates how the developmental vulnerabilities in childhood, limited opportunities in adulthood, and the provoking agents in their current lives interact and undermine well-being. This paper raises the proposition that a levelling process may occur in later life when these factors converge and result in distress irrespective of cultural differences.

Effect of melittin on prostaglandin production by guinea-pig uterus.

Melittin, an activator of phospholipase (PL) A-2, increased the outputs of prostaglandin (PG) F-2 alpha and 6-keto-PGF-1 alpha, but not of PGE-2, from Day-7 guinea-pig uterus superfused in vitro. Reducing the extracellular calcium concentration (by omitting calcium chloride from the superfusing fluid) partially inhibited the stimulatory effect of melittin on uterine PG production. TMB-8 (an intracellular calcium antagonist) completely prevented the stimulation of PGF-2 alpha and 6-keto-PGF-1 alpha output by melittin, although the production of both PGs tended to increase after stopping the melittin and TMB-8 treatments. TMB-8 also inhibited the increases in outputs of PGF-2 alpha, 6-keto-PGF-1 alpha and PGE-2 and prevented contraction of the uterus induced by exogenous PLA-2. Trifluoperazine (a calmodulin antagonist) had no inhibitory effect on the increases in outputs of PGF-2 alpha and 6-keto-PGF-1 alpha produced by melittin; it potentiated the stimulatory effect of melittin on 6-keto-PGF-1 alpha output and allowed melittin to increase PGE-2 output. When melittin was applied twice to the superfused uterus with an interval of 1 h between each treatment, partial refractoriness of the responses to melittin was seen: the magnitudes of the increases in PGF-2 alpha and 6-keto-PGF-1 alpha outputs were 40-50% less after the second treatment than after the first treatment. These results show that melittin stimulates the synthesis of PGF-2 alpha and PGI-2 (measured as 6-keto-PGF-1 alpha) in guinea-pig uterus by mechanisms which are calcium dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

A prion-like protein from chicken brain copurifies with an acetylcholine receptor-inducing activity.

The mammalian prion protein (PrPC) is a cellular protein of unknown function, an altered isoform of which (PrPSc) is a component of the infectious particle (prion) thought to be responsible for spongiform encephalopathies in humans and animals. We report here the isolation of a cDNA that encodes a chicken protein that is homologous to PrPC. This chicken prion-like protein (ch-PrLP) is identical to the mouse PrP at 33% of its amino acid positions, including an uninterrupted stretch of 24 identical residues, and it displays the same structural domains. In addition, ch-PrLP, like its mammalian counterpart, is attached to the cell surface by a glycosyl-phosphatidylinositol anchor. We find that ch-PrLP is the major protein in preparations of an acetylcholine receptor-inducing activity that has been purified greater than 10(6)-fold from brain on the basis of its ability to stimulate synthesis of nicotinic receptors by cultured myotubes. The ch-PrLP gene is expressed in the spinal cord and brain as early as embryonic day 6; and in the spinal cord, the protein appears to be concentrated in motor neurons. Our results therefore raise the possibility that prion proteins serve normally to regulate the chemoreceptor number at the neuromuscular junction and perhaps in the central nervous system as well.

Development of central projections of lumbosacral sensory neurons in the chick.

The development of central projections of sensory neurons in lumbosacral dorsal root ganglia (DRGs) was examined by using horseradish peroxidase labeling techniques in chick embryos from stage 23 (E4) to stage 39 (E13). Our results show that primary afferents reach the spinal cord by stage 23. Afferent axons extend in the primordium of the dorsal funiculus for several segments rostral and caudal to their segment of entry for over 24 hours before invading the gray matter at stage 28 (E6). Sensory fibers grow into the vicinity of motoneuron dendrites by stage 32 (E7.5), about the time that reflexes and apparent monosynaptic EPSPs can first be elicited. Dense projections into the dorsal laminae of the spinal cord, presumably representing cutaneous afferents, appear somewhat later, at about stage 39 (E13), when the segmental projection pattern begins to resemble the mature pattern.

Alexithymia and chronic respiratory disease. A review of current research.

Alexithymia within a chronic respiratory illness population has been given considerable attention in the psychiatric/psychological literature over the course of the past 5 years. Various observations as to the alexithymic trait within the chronic respiratory diseases (asthma, chronic bronchitis/emphysema, and tuberculosis) have revealed significant findings as to the manner in which alexithymia manifests itself and impacts on chronic respiratory disease. The present paper reviews the literature on alexithymia that has emanated from National Jewish Hospital and Research Center/National Asthma Center and raises questions for future research as regards alexithymia in chronic respiratory diseases.

Alexithymia in chronic bronchitis/emphysema patients. Communication of subjective symptomatology.

Affective, somatic, and collateral experiences of alexithymic and nonalexithymic patients to their chronic bronchitis/emphysema was analyzed in reference to 11 symptom categories of the Bronchitis/Emphysema Symptom Checklist. Unlike alexithymic asthmatics who tend to minimize their self-reports of physical and emotional difficulties during acute illness episodes, chronic bronchitis/emphysema alexithymics do not differ from nonalexithymics in their self-reports of physical and emotional difficulties.

Proton nuclear magnetic resonance investigation of the mechanism of flavin C-4a adduct formation induced by oxidized nicotinamide adenine dinucleotide binding to monoalkylated pig heart lipoamide dehydrogenase.

The active center thiol of monoalkylated pig heart lipoamide dehydrogenase, EHR, is induced to form an adduct to the enzyme-bound flavin adenine dinucleotide (FAD) at the C-4a position upon binding oxidized nicotinamide adenine dinucleotide (NAD+) [Thorpe, C., & Williams, C. H., Jr. (1976) J. Biol. Chem. 251, 7726-7728]. In light of hypotheses on covalent electron transfer between pyridine nucleotide and flavin, the induction of the thiol-flavin C-4a adduct by NAD+ is reasonably envisioned as involving a covalent bond between the modified flavin and the NAD+. The double-resonance proton nuclear magnetic resonance technique of cross saturation was used to probe the existence of covalent bond formation between the modified flavin of EHR and its inducer molecule, NAD+. Cross-saturation of the free NAD+ signals was not observed even though the spin-lattice relaxation time of NAD+ and the rate of exchange between free NAD+ and NAD+ bound to EHR were well within the limits required for cross-saturation. We conclude that a noncovalent interaction between NAD+ and FAD induces the formation of the thiol-flavin C-4a covalent adduct in EHR. A model by which NAD+ binding induces nucleophilic attack by the nascent thiolate of EHR is discussed.

A micro-analysis of "senility": the responses of the family and the health professionals.

In research on 167 post-hospitalized older people, thirty individuals were described by their families as being senile. In comparisons of the behaviorally impaired with those who have only a physical condition, it was found that the behaviorally impaired were significantly more likely to be placed in a nursing home than were those with serious physical impairment. In this sub-group, the family also was much more likely to seek-out health professionals for advice in the disposition of the patient, although mental health professionals were rarely consulted. Through a case study analysis, we analyze the interactions between the patients, their families and the health professions as a three-stage process where the patient's behaviors become increasingly specified and elaborated. As a result behaviors formerly tolerated become a formal problem where the solution is likely to be institutionalization.

Determination of a low pK for histidine-159 in the S-methylthio derivative of papain by proton nuclear magnetic resonance spectroscopy.

Proton NMR spectroscopy was used to study the ionization behavior of His-159 in a derivative of papain (papain-S-SCH3). In this catalytically inactive derivative of papain, the active-site thiol group of Cys-25 is S-methyl-thiolated so that it cannot form a thiolate anion. The pH dependence of the chemical shift of the C epsilon 1 H resonance of His-159 indicated a pK of 3.45 +/- 0.07 at 45 degrees C in 2H2O with no added ions other than those required for titration. In acetate buffers at an ionic strength of 0.05, the pK increased to 3.87 +/- 0.12. Conversion of papain-S-SCH3 to active papain at pH* 4.17 (at 45 degrees C and an ionic strength of 0.05) caused the position of the C epsilon 1 H resonance to change from a position indicative of partial protonation of His-159 to a position indicative of full protonation, consistent with the existence of an imidazolium-thiolate ion-pair interaction between His-159 and Cys-25 in the active enzyme.

Perturbations in the free energy and enthalpy of ionization of histidine-159 at the active site of papain as determined by fluorescence spectroscopy.

Fluorometric titrations of papain, succinyl-papain, and the corresponding methylthio derivatives of Cys-25 (papain-S-SCH3 and succinyl-papain-S-SCH3) were determined. Removal of the methylthio group from Cys-25 resulted in an increase of approximately 4 pK units in the fluorometrically determined pK value. The correspondence between the ionization behavior as determined by proton NMR and fluorometric titrations indicated that fluorescence titrations reflect the ionization behavior of His-159 in both the active enzyme and the methylthio derivative. The ionic strength dependence of the pK was analyzed in terms of simple electrostatic theory and was shown to be consistent with the charge on the protein. The temperature dependence of the pK values of His-159 indicated an increase in the heat of ionization from about 0 to 8 kcal/mol upon removal of the methylthio blocking group from Cys-25. Measurements of the effect of solvent on the pK's and heats of ionization of simple model compounds indicated that the observed shift in enthalpy of ionization of His-159 upon removal of th methylthio group from Cys-25 is not unreasonable in light of the accompanying perturbation is more than 4 pK units in the pK of His-159. The perturbations in enthalpies and free energies are attributed to formation of an ion pair. The ionization behavior of His-159 in thiol-blocked derivatives of papain is consistent with the involvement of His-159 in the deacylation step in papain catalysis.

Effect of cysteine-25 on the ionization of histidine-159 in papain as determined by proton nuclear magnetic resonance spectroscopy. Evidence for a his-159--Cys-25 ion pair and its possible role in catalysis.

Papain was succinylated in order to increase its solubility above pH 8 so that proton NMR spectroscopy could be used to study the ionization of His-159 at the active site of the enzyme. The pH dependence of NMR spectra of catalytically active succinyl-papain and the methylthio derivative of the active-site cysteinyl residue of succinyl-papain (succinyl-papain-S-SCH3) were determined between pH 6 and 10. The pH dependence of the C epsilon 1 H resonance of His-159 in catalytically active succinyl-papain indicates that His-159 has a pK of about 8.6 in the catalytically active form of the enzyme. The position of this resonance in succinyl-papain-S-SCH3 indicates that when the active-site cysteinyl residue is methylthiolated, His-159 is completely deprotonated between pH 6 and 10. This result is taken as evidence for an imidazolium--thiolate ion-pair interaction between His-159 and Cys-25 wherein neutralization of the charge on the thiolate anion by methylthiolation would be expected to cause a marked decrease in the pK of His-159. A possible catalytic role for the ion pair in the acylation step in papain-catalyzed reactions is proposed wherein attack of a substrate by the imidazolium--thiolate ion pair is accompanied by an increase in the acidity of the imidazolium group that facilitates expulsion of the leaving group of the substrate.

Quality of drawing as a factor in the interpretation of figure drawings.

Examined the drawings of 32 poliomyelitis patients and their matched controls to see whether figure drawings primarily reflect the subject's projection of psychological state, ability to draw, or some combination of these two factors. An overview of the literature is also given. Drawings from disabled and nondisabled subjects were reliably rated for quality, with no significant quality difference found between groups. Analyses of variance were then used to compare the drawings on several different measures of drawing size, completion and movement that might be assumed on the basis of the literature, to reflect the subjects' projection of disability status. Results showed that quality of drawing was a significant factor in 13 of the 17 comparisons while disability status proved to be a significant factor in only one of the 17 comparisons. There were no significant interactions. Therefore, the overall findings are consistent with the hypothesis that quality of drawing-rather than projective mechanisms-may at times be the overwhelming determinant of clinical and research findings with figure drawings.

Dependence of the catalytic activity of papain on the ionization of two acidic groups.

The pH dependence of kcat/Km for the papain-catalyzed hydrolysis of ethyl hippurate, N-alpha-benzoyl-L-citrulline methyl ester, and the p-nitroanilide, amide, and ethyl ester derivatives of N-alpha-benzoyl-L-arginine was determined below pH 6.4. The value of kcat/Km was observed to be modulated by two acid ionizations rather than a single ionization as previously believed. For the five substrates studied, the average pK values for the two ionizations are 3.78 +/- 0.2 and 3.95 +/- 0.1 at T/2 0.3, 25 degrees C. The observation that similar pK values were obtained with different substrates was taken as evidence that the kinetically determined pK values are close in value to true macroscopic ionization constants for ionization of groups on the free enzyme.