Emersion behaviour underlies variation in gill morphology and aquatic respiratory function in the amphibious fish Kryptolebias marmoratus.

Fishes acclimated to hypoxic environments often increase gill surface area to improve O2 uptake. In some species, surface area is increased via reduction of an interlamellar cell mass (ILCM) that fills water channels between gill lamellae. Amphibious fishes, however, may not increase gill surface area in hypoxic water because these species can, instead, leave water and breathe air. To differentiate between these possibilities, we compared wild amphibious mangrove rivulus Kryptolebias marmoratus from two habitats that varied in O2 availability - a hypoxic freshwater pool versus nearly anoxic crab burrows. Fish captured from crab burrows had less gill surface area (as ILCMs were enlarged by ∼32%), increased rates of normoxic O2 consumption and increased critical O2 tension compared with fish from the freshwater pool. Thus, wild mangrove rivulus do not respond to near-anoxic water by decreasing metabolism or increasing O2 extraction. Instead, fish from the crab burrow habitat spent three times longer out of water, which probably caused the observed changes in gill morphology and respiratory phenotype. We also tested whether critical O2 tension is influenced by genetic heterozygosity, as K. marmoratus is one of only two hermaphroditic vertebrate species that can produce both self-fertilized (inbred) or out-crossed (more heterozygous) offspring. We found no evidence for inbreeding depression, suggesting that self-fertilization does not impair respiratory function. Overall, our results demonstrate that amphibious fishes that inhabit hypoxic aquatic habitats can use a fundamentally different strategy from that used by fully aquatic water-breathing fishes, relying on escape behaviour rather than metabolic depression or increased O2 extraction ability.

Relationship between pediatric blood and marrow transplant center volume and day +100 mortality: Pediatric Blood and Marrow Transplant Consortium experience.

The number of patients receiving a BMT is currently being used as a factor in the accreditation process in determining whether a center can provide a high-quality BMT. Such criteria particularly impact pediatric BMT centers as most of them perform a relatively small number of BMTs. To determine whether patient volume is a valid marker of pediatric BMT center's capabilities, the Pediatric Blood and Marrow Transplant Consortium (PBMTC) evaluated data from its registry to define the relationship between a pediatric transplant center's patient volume and day +100 mortality. The analyses evaluated 2575 transplants from 60 centers reporting to the PBMTC between the years 2002 and 2004. The volume-outcome relationship was evaluated while adjusting for 46 independent data categories divided between nine variables that were known- or suspected-mortality risk factors. We found no association between transplant center volume and day +100 mortality in several analyses. A calculated intraclass correlation coefficient also indicated that differences in individual transplant center volume contributed to only 1% of the variance in day +100 mortality within the PBMTC. The results of this study suggest that factors other than transplant center volume contribute to variation in day +100 mortality among pediatric patients.

Diagnosis from fundus photographs.

AIM: To investigate the way in which ophthalmologists observe fundi and make diagnoses from their observations. METHODS: A set of 12 test photographs was presented to 9 ophthalmologists. The subjects were asked to identify the features in the photographs that are important for forming a diagnosis and were also asked to form differential diagnoses. The scanpaths of the subjects were recorded during their inspection of the photographs. Subsequently, they were asked to trace over the important features of four of the photographs. RESULTS: The correctness of the diagnoses was described by weighted numerical scores. Differential diagnoses made after 30 s of inspection were significantly better than those made after 5 s. Irrespective of correctness, the reported diagnoses were dominated by the most obvious features of the photograph. Incorrect diagnoses were made either because the subjects failed to identify the significant features of the photograph or because they failed to comprehend the significance of the identified features. CONCLUSION: Accurate funduscopy involves both perception of diagnostic features and cognitive interpretation of these features. Verbal reports, eye movement recordings and tracings reveal the features and interpretations used to make a diagnosis. These techniques will be used in a subsequent study to evaluate the relative contributions of formal training and experience to the development of diagnostic skills.

The achiasmia spectrum: congenitally reduced chiasmal decussation.

AIM: To describe the clinical spectrum of achiasmia, a congenital disorder of reduced relative decussation at the optic chiasm. METHODS: A retrospective case note and patient review of nine children (four boys). Achiasmia was defined by the combination of a characteristic asymmetry of the monocular visual evoked potential (VEP) response to flash and neuroimaging showing reduced chiasmal size. RESULTS: Three of the children had an associated skull base encephalocele with agenesis of the corpus callosum. In two patients achiasmia was associated with septo-optic dysplasia. Three patients had no neuroimaging abnormalities other than reduced chiasmal size and have no known pituitary dysfunction. One child had multiple physical deformities but the only brain imaging abnormality was reduced chiasmal size. CONCLUSIONS: Some children with disorders of midline central nervous system development, including septo-optic dysplasia and skull base encephaloceles, have congenitally reduced chiasmal decussation. Reduced relative decussation may co-exist with overall chiasmal hypoplasia. Children with an apparently isolated chiasmal decussation deficit may have other subtle neurological findings, but our clinical impression is that most of these children function well.

Calcium intake and peak bone mass.

Studying the relationship between calcium intake and peak bone mass in adolescent women is complicated by several factors. Calcium intake and calcium absorption are interrelated and can vary widely for the same individual, as well as among individuals. Modifiable determinants that affect bone gain in the peripheral skeleton do not necessarily have the same effect on the axial skeleton. In addition to these physiological factors, differences in study design make comparisons difficult. Study cohorts have varied in age, size, and pubertal status; bone measurements have been made at different sites with different equipment; and calcium intakes have been measured in different ways. Other important variables include endocrine maturation patterns and physical activity levels. Given this complex relationship, the amount of calcium young women need to achieve peak bone mass remains unclear. There is no convincing evidence, however, that they need more than 900 mg/day.

Spontaneous reversal of nystagmus in the dark.

AIM: To report five children with horizontal jerk nystagmus in whom eye movement recordings in the dark revealed a spontaneous reversal in the direction of the nystagmus beat. Three patients were blind in one eye and were diagnosed as having a manifest latent nystagmus (MLN), and two patients had strabismus and congenital nystagmus (CN). METHODS: Eye movements were recorded using DC electro-oculography with simultaneous video recording, including infrared recording in total darkness. RESULTS: Four patients had decelerating velocity slow phase jerk nystagmus when recorded under natural lighting conditions; the fifth case had accelerating velocity and linear slow phase jerk nystagmus. Under absolute darkness, nystagmus reversed in direction of beat with a mixture of linear and decelerating velocity slow phase waveforms. One child with unilateral anophthalmos could wilfully reverse the beat direction of his nystagmus by trying to look with his blind eye in the light and dark. CONCLUSIONS: These observations support the theory that LN/MLN beat direction is determined by the "presumed" viewing eye and may be consciously controlled. The spontaneous reversal of beat direction in the dark suggests eye dominance is predetermined. Eye movement recordings identified mixed nystagmus waveforms indicating that CN (accelerating velocity slow phases) and LN/MLN (linear/decelerating velocity slow phases) coexist in these subjects.

Illegitimate Cre-dependent chromosome rearrangements in transgenic mouse spermatids.

The bacteriophage P1 Cre/loxP system has become a powerful tool for in vivo manipulation of the genomes of transgenic mice. Although in vitro studies have shown that Cre can catalyze recombination between cryptic "pseudo-loxP" sites in mammalian genomes, to date there have been no reports of loxP-site infidelity in transgenic animals. We produced lines of transgenic mice that use the mouse Protamine 1 (Prm1) gene promoter to express Cre recombinase in postmeiotic spermatids. All male founders and all Cre-bearing male descendents of female founders were sterile; females were unaffected. Sperm counts, sperm motility, and sperm morphology were normal, as was the mating behavior of the transgenic males and the production of two-celled embryos after mating. Mice that expressed similar levels of a derivative transgene that carries an inactive Cre exhibited normal male fertility. Analyses of embryos from matings between sterile Cre-expressing males and wild-type females indicated that Cre-catalyzed chromosome rearrangements in the spermatids that lead to abortive pregnancies with 100% penetrance. Similar Cre-mediated, but loxP-independent, genomic alterations may also occur in somatic tissues that express Cre, but, because of the greater difficulty of assessing deleterious effects of somatic mutations, these may go undetected. This study indicates that, following the use of the Cre/loxP site-specific recombination systems in vivo, it is prudent to eliminate or inactivate the Cre recombinase gene as rapidly as possible.

Oral contraceptive use by teenage women does not affect peak bone mass: a longitudinal study.

OBJECTIVE: To determine the effect of oral contraceptive pill (OCP) use during adolescence on peak bone mass. DESIGN: Longitudinal observational study. SETTING: Academic clinical research center. PATIENT(S): Sixty-two non-Hispanic, white females in The Penn State Young Women's Health Study, who were studied for 8 years during ages 12-20. INTERVENTION(S): There were 28 OCP users, who used OCPs for a minimum of 6 months and were still using at age 20, and 34 nonusers who had never used OCPs. MAIN OUTCOME MEASURE(S): Total body bone, dedicated hip bone, and body composition measurements were made by dual-energy roentgenogram absorptiometry. RESULT(S): The OCP users and nonusers did not differ at entry in anthropometric, body composition, or total body bone measurements. By age 20, the average duration of OCP use by the user group was 22 months. At age 20, the groups remained indistinguishable in anthropometric, body composition, total body, and hip bone measures, and in age of menarche and sports exercise scores. CONCLUSION(S): Oral contraceptive pill use by healthy, white, teenage females does not affect acquisition of peak bone mass.

PIP: This longitudinal observational study determined the effect of oral contraceptive (OC) use during adolescence on peak bone mass (PBM). The sample comprised 62 non-Hispanic, White females in The Penn State Young Women's Health Study, who were studied for 8 years between the ages of 12 and 20. There were 28 OC users who used OCs for a minimum of 6 months and were still using them at age 20, and 34 nonusers who had never used the regimen. Total body bone, dedicated hipbone, and body composition measurements were made by dual-energy roentgenogram absorptiometry. There was no difference between OC users and nonusers in the anthropometric, body composition, or total body bone measurements. By age 20, the average duration of OC use by the user group was 22 months. At this age, the groups remained indistinguishable in anthropometric, body composition, total body, and hipbone measurements, and in age of menarche and sports exercise scores. These findings suggest that OC use by healthy, White, teenage females does not affect acquisition of PBM.

Vigabatrin-associated visual field defects in children.

PURPOSE: Vigabatrin (Sabril), a drug that blocks GABA transaminase, has been used in the treatment of epilepsy since 1989. There have been reports of irreversible constriction of the visual field in adult patients related to vigabatrin (VGB) therapy, resulting in reduced VGB usage in adults. Although used as a second or third line agent in adults, in children it is often considered as a first line treatment for several subgroups of seizures in spite of there being no way, in the majority of cases, to monitor visual fields. Some of these children have a pre-existing visual field defect as part of their primary disorder. We aimed to identify whether visual field loss due to VGB was occurring in our hospital. METHODS: We have studied the results of ophthalmic examination in 14 children on VGB at Great Ormond Street Hospital who were able to perform Goldmann visual fields. RESULTS: Ten of the 14 patients had constriction of their visual fields attributed to VGB. In addition there were 2 patients with suspicious visual field defects thought to be due to VGB. There was pre-existing visual pathway damage in 4 cases and in 2 of these optic disc pallor increased in association with constricted visual fields. However, the optic discs were normal in 7 patients in spite of visual field constriction. Visual acuity was generally normal in spite of gross visual field constriction. CONCLUSIONS: We believe that VGB should be used with great caution where there is pre-existing visual pathway damage. In other cases the benefits should be considered in relation to the risks, which include irreversible visual field damage. At present visual fields can only be monitored by perimetry, which is often not possible in children with epilepsy.

Esophageal involvement in Wegener's granulomatosis: a case report and review of the literature.

Wegener's granulomatosis is characterized by a granulomatous arteritis involving the upper and lower respiratory tracts, progressive glomerulonephritis and systemic symptoms attributable to small vessel vasculitis. Although multisystemic manifestations are frequent, involvement of the gastrointestinal tract is uncommon. Cases have been reported of intestinal perforation, ulceration and hemorrhage. A patient whose initial presentation of Wegener's granulomatosis was odynophagia secondary to esophageal vasculitis is described. Endoscopy revealed multiple punched out ulcerations in the esophagus, which resolved with standard therapy for systemic Wegener's granulomatosis. There are only two previous reports of symptomatic esophageal vasculitis in patients with Wegener's granulomatosis. These reports illustrate the need to consider odynophagia as a reflection of disease activity as opposed to complications of immunosuppressive therapy.

A study of EEG, electroretinogram, visual evoked potential, and eye movements in classical lissencephaly.

EEG, flash electroretinogram (ERG), and visual evoked potential (VEP) findings are described in eight children with classical lissencephaly (six girls, two boys), with a mean age of 17.6 months (range 2 to 60 months). The EEG shows typically high-voltage activity. Eye movements were formally recorded in two patients, and both showed features associated with oculomotor apraxia. The ERG and VEP to flash stimulation were normal in all cases. Two subjects had pattern reversal stimulation, and their pattern VEPs were within normal limits. Some patients with lissencephaly may appear to have delayed visual maturation on first presentation, and EEG and eye movement studies are valuable in indicating neurological deficiency at an early stage in these subjects.

Polyunsaturated fatty acids in the food chain in the United States.

In the United States, intake of n-3 fatty acids is approximately 1.6 g/d ( approximately 0.7% of energy), of which 1.4 g is alpha-linolenic acid (ALA; 18:3) and 0.1-0.2 g is eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6). The primary sources of ALA are vegetable oils, principally soybean and canola. The predominant sources of EPA and DHA are fish and fish oils. Intake data indicate that the ratio of n-6 to n-3 fatty acids is approximately 9.8:1. Food disappearance data between 1985 and 1994 indicate that the ratio of n-6 to n-3 fatty acids has decreased from 12.4:1 to 10.6:1. This reflects a change in the profile of vegetable oils consumed and, in particular, an approximate 5.5-fold increase in canola oil use. The ratio of n-6 to n-3 fatty acids is still much higher than that recommended (ie, 2.3:1). Lower ratios increase endogenous conversion of ALA to EPA and DHA. Attaining the proposed recommended combined EPA and DHA intake of 0.65 g/d will require an approximately 4-fold increase in fish consumption in the United States. Alternative strategies, such as food enrichment and the use of biotechnology to manipulate the EPA and DHA as well as ALA contents of the food supply, will become increasingly important in increasing n-3 fatty acid intake in the US population.

Is there an optimal diet for the hypertriglyceridemic patient?

Many dietary factors affect plasma triglycerides. Those which decrease the triglyceride level include n-3 fatty acids from fish oil, weight loss, alcohol restriction, and a higher fat (unsaturated fat) diet, whereas a high-carbohydrate, low-fat diet increases triglycerides. The individual responses and the associated magnitude of change in triglycerides as a result of these different dietary factors will vary. For patients with hypertriglyceridemia, fish oil supplements will usually elicit the most potent effects. However, some patients can normalize their triglyceride level with weight loss plus exercise, by avoiding or limiting their alcohol intake, and by increasing the total fat content of their diet. In addition, fish oil supplements can help further to reduce plasma triglycerides. Thus, the combined effects of multiple dietary interventions provide the most potent means of maximally lowering the plasma triglyceride level.

Visual-evoked potential evidence of chiasmal hypoplasia.

PURPOSE: To show that chiasmal hypoplasia or aplasia need not be an isolated developmental anomaly and to examine the spectrum of associated clinical findings to explore the possibility that these patients may represent a phenotypic manifestation of a developmental gene anomaly. DESIGN: An observational case series. PARTICIPANTS: Five infants, between several weeks and 7 months of age, in whom the electrophysiologic characteristic of chiasmal hypoplasia had been noted were included. METHODS: Flash electroretinography and flash and pattern visual-evoked potentials (VEPs) were elicited from all patients. Clinical ophthalmologic examinations, including funduscopy, were performed, and all patients had magnetic resonance imaging (MRI) brain scans. MAIN OUTCOME MEASURES: The occipital distribution of monocular VEP response peaks was studied. The symmetry of lateral channel responses was compared for monocular stimulation. RESULTS: All five patients had a crossed asymmetry in the monocular VEP occipital distribution, which is consistent with a paucity of fibers crossing at the chiasm. The MRI findings supported this electrophysiologic observation, illustrating degrees of chiasmal hypoplasia and variable coincidence of other midline abnormalities of the brain. Optic disc appearances varied from normal to hypoplastic and colobomatous. CONCLUSIONS: The ophthalmologic and MRI findings of five patients who showed a crossed asymmetry in monocular flash VEPs are consistent with a paucity of axons crossing at the chiasm. The similarities between achiasmia in humans and mice due to a Pax2 gene anomaly are discussed.

The eye in epidermolysis bullosa.

AIMS: To describe the ophthalmic findings in a large cohort of epidermolysis bullosa (EB) patients managed in one large specialist centre. METHODS: A case note review of consecutive patients seen at Great Ormond Street Children's Hospital. Data on the dermatological disease, ophthalmic history, and examination were collected and coded onto a data sheet. RESULTS: 181 patients: 50 (28%) simplex EB; 15 (8%) junctional EB; 28 (15%) autosomal dominant dystrophic EB; 72 (40%) autosomal recessive dystrophic EB; nine patients (5%) with dystrophic EB whose inheritance could not be ascertained; and seven cases (4%) of EB that could not be classified. Ocular problems were found in 12% (n = 6) of simplex patients and 40% (n = 6) of those with junctional disease. One patient (of 28) in the autosomal dominant dystrophic group had ocular involvement and 51% (37/72) of patients in the autosomal recessive dystrophic group had ophthalmic complications: corneal (25/72), lid ectropions (3/72), lid blisters (5/72), and symblepharon (3/72). CONCLUSION: Ophthalmic complications are common in EB overall but the incidence varies widely with subtype. Ophthalmic complications are the most severe in the dystrophic recessive and junctional subtypes where there is a need for extra vigilance. The major treatment modality was use of ocular lubricants.

Cultural control of larval mosquito production in a fallow citrus grove used for disposal of secondary-treated sewage effluent.

Larval mosquito production was monitored for 16 months in the furrows of a 13.4-ha citrus grove in east-central Florida used for disposal of secondary-treated sewage effluent. Twenty-one species of mosquito were collected, and the 2 most abundant species were Culex nigripalpus and Aedes vexans. An unplanned removal of all brush and trees from the site during the study resulted in an overall decline in larval production, but species diversity remained the same.

Use of a temporary indwelling ureteral stent catheter in a mare with a traumatic ureteral tear.

A 4-year-old primiparous Thoroughbred mare was referred for treatment of uroperitoneum subsequent to dystocia. Hematologic and serum biochemical analyses revealed values consistent with those reported for foals with uroperitoneum. Exploratory celiotomy revealed the source of the uroperitoneum to be a rent in the right ureter proximal to the trigone of the bladder. Substantial accumulation of urine in the tissues surrounding the ureter prevented accurate identification and repair of the defect, so a temporary indwelling ureteral stent catheter was inserted. Three weeks later, the stent catheter was removed, and the mare made a complete recovery with restoration of continuity of the urinary tract and preservation of function of the affected kidney. Use of this procedure offers a practical alternative to unilateral nephrectomy or ureteronephrectomy for traumatic ureteral injuries of horses.

Novel cardiovascular actions of the activins.

Proliferation and directed migration of vascular cells are key components in vascular diseases such as atherosclerosis and restenosis following percutaneous transluminal coronary angioplasty. However, the precise cellular and molecular mechanisms involved in the control of vascular cell proliferation or migration at the tissue level remain largely undefined. Molecules contributing to these processes are elaborated by distinct cell types and act in both autocrine and paracrine modes. They include two broad classes, polypeptide growth factors and vasoactive G-protein-coupled receptor (GPCR) agonists. Examples of the former, such as platelet-derived growth factor, bind to and activate cell surface receptor tyrosine kinases, initiating intracellular biochemical signaling pathways associated with cell proliferation or migration. In contrast, recent evidence suggests that vasoactive GPCR agonists (e.g. angiotensin II, endothelin-1, alpha-thrombin) elicit cell growth indirectly by inducing the production of autocrine or paracrine factors in vascular cells. Recent studies have identified activin A as a novel component of conditioned medium obtained from GPCR agonist-stimulated vascular smooth muscle cells (SMCs). Although activin A alone only weakly stimulated rat aortic SMC DNA synthesis, it demonstrated a potent co-mitogenic effect in combination with either epidermal growth factor (EGF) or heparin binding EGF-like growth factor in these cells, increasing DNA synthesis by up to 5- and 4-fold respectively. Furthermore, in a rat carotid-injury model, activin A mRNA was upregulated within 6 h after injury, followed by increases in immunoreactive protein detected in the expanding neointima 7 to 14 days later. Taken together, these results indicate that activin A is a common vascular SMC-derived growth factor induced by vasoactive agonists that may, either alone or in combination with other factors, contribute to fibroproliferative vascular diseases.

Epiregulin is a potent vascular smooth muscle cell-derived mitogen induced by angiotensin II, endothelin-1, and thrombin.

Vasoactive GTP-binding protein-coupled receptor agonists such as angiotensin II (AII), endothelin-1 (ET-1), and alpha-thrombin (alpha-Thr) have been reported to indirectly stimulate vascular smooth muscle cell (VSMC) proliferation by regulating the expression of one or more autocrine growth factors. Using ion-exchange, gel-filtration, and reverse-phase chromatographic purification methods, we isolated a major mitogenic protein present in AII-stimulated rat aortic smooth muscle (RASM) cell conditioned medium. Twenty N-terminal amino acids of the purified peptide were identified, and they had 75% amino acid sequence identity with mouse epiregulin, an epidermal growth factor (EGF)-related growth factor. We cloned the cDNA for rat epiregulin to determine its pattern of expression in G-protein-coupled receptor agonist-stimulated cells and confirm its activity as a mitogen. After treatment of RASM cells with AII, ET-1, or alpha-Thr for 1 h, induction of two epiregulin transcripts was observed, including a 4.8-kb transcript and a novel transcript of approximately 1.2 kb. Recombinant rat epiregulin was strongly mitogenic for RASM cells, stimulating DNA synthesis to levels similar to those induced by serum or platelet-derived growth factor and approximately 3-fold above that observed with saturating concentrations of EGF. In addition, epiregulin caused rapid EGF receptor activation in RASM cells. However, relative levels of EGF receptor tyrosine phosphorylation stimulated by epiregulin were less than those induced by EGF or betacellulin. Taken together, these results indicate that epiregulin is a potent VSMC-secreted mitogen, induced in common by AII, ET-1, and alpha-Thr, that may contribute to VSMC proliferation and vascular remodeling stimulated by vasoactive agonists.