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.

Differential alteration by thalidomide of the glutathione content of rat vs. rabbit conceptuses in vitro

Thalidomide has been shown to cause limb reduction defects in rabbits with much greater potency than in rats, possibly due to inherent biochemical differences between the two species. Whole embryo culture was used to make direct comparisons between thalidomide-sensitive New Zealand White rabbits and thalidomide-resistant Sprague-Dawley rats, focusing on the possible roles of glutathione (GSH) and cysteine in mechanisms of thalidomide teratogenicity. Conceptuses were treated by adding thalidomide (0, 5, 15, and 30 microM) directly to the culture media containing conceptuses of similar gestational stages. Embryos and visceral yolk sacs (VYS) were measured for changes in GSH and cysteine content using HPLC after 24 h of exposure in vitro. Thalidomide-induced (15 and 30 microM) depletion of VYS GSH occurred only in the rabbit, where GSH concentrations (pmol/microg protein) fell significantly to about 50% of control. Rat VYS did not show a significant GSH depletion at any thalidomide concentration tested. Comparison between species showed that the control rabbit VYS contained 35% less GSH than the control rat VYS. Control rat embryos and control rabbit embryos contained similar concentrations of GSH, but thalidomide treatment preferentially depleted GSH in the rabbit at lower thalidomide concentrations (5 micro/M). Cysteine concentrations were not significantly altered from control in the embryo or VYS of either species when treated with thalidomide. However, although control cysteine concentrations did not differ significantly between rat and rabbit VYS, control cysteine levels in rabbit embryos were 65% lower than those in control rat embryos. Rabbit conceptuses displayed lower species-specific GSH and cysteine levels and a greater propensity for thalidomide-induced GSH depletion than in rat conceptuses, consistent with the greater sensitivity of the rabbit to thalidomide teratogenicity. These thalidomide-induced and inherent species differences implicate a possible role for GSH and redox status in the mechanisms of thalidomide teratogenicity.

A unique effect of clonazepam on frontal lobe seizure control

In a 16-year-old female, clonazepam (CZP) changed randomly occurring intractable tonic seizures of frontal lobe origin to a few sleep seizures when used as an adjunctive therapy. The significance of this change in the seizure pattern is discussed with an explanation of possible pathophysiologic mechanism.

Electron backscatter diffraction of grain and subgrain structures - resolution considerations

Characterization of microstructures containing small grains or low-angle grain boundaries by electron backscattered diffraction (EBSD) is limited by the spatial and angular resolution limits of the technique. It was found that the best effective spatial resolution (60 nm) for aluminium alloys in a tungsten-filament scanning electron microscope (SEM) was obtained for an intermediate probe current which provided a compromise between pattern quality and specimen interaction volume. The same specimens and EBSD equipment when used with a field-emission gun SEM showed an improvement in spatial resolution by a factor of 2-3. For characterizing low-angle boundary microstructures, the precision of determining relative orientations is a limiting factor. It was found that the orientation noise was directly related to the probe current and this was interpreted in terms of the effect of probe current on the quality of the diffraction patterns.

Regulation and characterization of the Na+/H+ exchanger

The Na+/H+ exchanger is a ubiquitous protein present in all mammalian cell types that functions to remove one intracellular H+ for one extracellular Na+. Several isoforms of the protein exist, which are referred to as NHE1 to NHE6 (for Na+/H+ exchanger one through six). The NHE1 protein was the first isoform cloned and studied in a variety of systems. This review summarizes recent papers on this protein, particularly those that have examined regulation of the protein and its expression and activity.

Suicide within 12 months of contact with mental health services: national clinical survey

OBJECTIVE

To describe the clinical circumstances in which psychiatric patients commit suicide.

DESIGN

National clinical survey.

SETTING

England and Wales.

SUBJECTS

A two year sample of people who had committed suicide, in particular those who had been in contact with mental health services in the 12 months before death.

MAIN OUTCOME MEASURES

Proportion of suicides in people who had had recent contact with mental health services; proportion of suicides in inpatients; proportion of people committing suicide and timing of suicide within three months of hospital discharge; proportion receiving high priority under the care programme approach; proportion who were recently non-compliant and not attending.

RESULTS

10 040 suicides were notified to the study between April 1996 and March 1998, of whom 2370 (24%; 95% confidence interval 23% to 24%) had had contact with mental health services in the year before death. Data were obtained on 2177, a response rate of 92%. In general these subjects had broad social and clinical needs. Alcohol and drug misuse were common. 358 (16%; 15% to 18%) were psychiatric inpatients at the time of death, 21% (17% to 25%) of whom were under special observation. Difficulties in observing patients because of ward design and nursing shortages were both reported in around a quarter of inpatient suicides. 519 (24%; 22% to 26%) suicides occurred within three months of hospital discharge, the highest number occurring in the first week after discharge. 914 (43%; 40% to 44%) were in the highest priority category for community care. 488 (26% excluding people whose compliance was unknown; 24% to 28%) were non-compliant with drug treatment while 486 (28%; 26% to 30%) community patients had lost contact with services. Most people who committed suicide were thought to have been at no or low immediate risk at the final service contact. Mental health teams believed suicide could have been prevented in 423 (22%; 20% to 24%) cases.

CONCLUSIONS

Several suicide prevention measures in mental health services are implied by these findings, including measures to improve compliance and prevent loss of contact with services. Inpatient facilities should remove structural difficulties in observing patients and fixtures that can be used in hanging. Prevention of suicide after discharge may require earlier follow up in the community. Better suicide prevention in psychiatric patients is likely to need measures to improve the safety of mental health services as a whole, rather than specific measures for people known to be at high risk.

Mental disorder and clinical care in people convicted of homicide: national clinical survey

OBJECTIVES

To estimate the rate of mental disorder in those convicted of homicide and to examine the social and clinical characteristics of those with a history of contact with psychiatric services.

DESIGN

National clinical survey.

SETTING

England and Wales.

SUBJECTS

Eighteen month sample of people convicted of homicide.

MAIN OUTCOME MEASURES

Offence related and clinical information collected from psychiatric court reports on people convicted of homicide. Detailed clinical data collected on those with a history of contact with psychiatric services.

RESULTS

718 homicides were reported to the inquiry between April 1996 and November 1997. Of the 500 cases for whom psychiatric reports were retrieved, 220 (44%; 95% confidence interval 40% to 48%) had a lifetime history of mental disorder, while 71 (14%; 11% to 17%) had symptoms of mental illness at the time of the homicide. Of the total sample, 102 (14%; 12% to 17%) were confirmed to have been in contact with mental health services at some time, 58 (8%; 6% to 10%) in the year before the homicide. The commonest diagnosis was personality disorder (20 cases, 22%; 13% to 30%). Alcohol and drug misuse were also common. Only 15 subjects (18%; 10% to 26%) were receiving intensive community care, and 60 (63%; 53% to 73%) were out of contact at the time of the homicide.

CONCLUSIONS

There are substantial rates of mental disorder in people convicted of homicide. Most do not have severe mental illness or a history of contact with mental health services. Inquiry findings suggest that preventing loss of contact with services and improving the clinical management of patients with both mental illness and substance misuse may reduce risk, but clinical trials are needed to examine the effectiveness of such interventions.

A trial of simple versus intensified dietary modification for prevention of progression to diabetes mellitus in women with impaired glucose tolerance

Women with impaired glucose tolerance are at high risk of developing noninsulin dependent diabetes mellitus (NIDDM). The Mercy Hospital for Women has a long-term follow-up programme for women with gestational diabetes, which identifies many women with impaired glucose tolerance. Two hundred of these women were entered into a randomized controlled trial of intensive versus routine dietary advice. Seven women were lost to follow-up. The annual incidence rates of diabetes mellitus for the 2 groups were 6.1% (intervention) and 7.3% (control), an incident rate ratio of 0.83, 95% confidence interval 0.47-1.48, p = 0.50. Overall, there was a return to normal glucose tolerance in 44% of patients. Multivariate analysis showed that body mass index, fasting and 2-hour plasma glucose levels at trial entry were significantly associated with an increased risk of diabetes mellitus. Impaired glucose tolerance is an important condition that should be treated with advice about lifestyle modification (diet and/or exercise). We consider that future trials in the management of women with previous gestational diabetes who have impaired glucose tolerance should investigate the effect of pharmacological intervention in addition to diet and/or exercise, the latter providing a therapy that it would be unethical to exclude on the evidence presently available.

Pyridine nucleotide flux and glutathione oxidation in the cultured rat conceptus

It is proposed that protection of the developing embryo from chemical and environmental insults that produces oxidative stress requires a proper glutathione (GSH) and pyridine nucleotide status in both the embryo and extra-embryonic membranes. Modulation of pyridine nucleotide flux [NAD(H) and NAD(P)H] in the visceral yolk sac (VYS) by the thiol oxidants diamide and tert-butyl hydroperoxide (tBH) was studied in real time using microfiberoptic sensors in GD 10 rat conceptuses. Consecutive 5-min exposures to 125- and 250-microM diamide resulted in a fluorescence decrease of 14 and 32 Arbitrary Fluorescence Units (AFU). An additional consecutive exposure to 500-microM diamide caused an attenuated decrease followed by a rebound increase of 22 AFU. Consecutive 5-min exposures to tBH at 250 and 500 microM produced fluorescence decreases similar to that of 500 microM diamide, but the decreases were attenuated at 1000 microM. However, there was variability in the rebound increase. A 5-min exposure to tBH (500 microM) alone caused a fluorescence decrease of 14 AFU followed by a rebound increase of 8 AFU. The rate of fluorescence decrease was attenuated by 50% with pretreatment with the glutathione reductase (GSSG-Rd) inhibitor, BCNU (1,3, bis(2 chloroethyl)-1-nitrosourea), indicating that the decrease in surface fluorescence was probably attributable to a decrease in NADPH. Decreases in fluorescence, observed from the surface of the VYS, correlated with decreases in GSH/GSSG ratios in the embryos and the VYS. After exposure to tBH, GSH levels in conceptuses decreased at the end of 5 and 15 min, with a corresponding increase in oxidized glutathione (GSSG) at the end of 3, 5, and 15 min. Our results demonstrate that the increased production of GSSG on exposure to thiol oxidants correlates with a decrease in the reduced pyridine nucleotide, implying the presence of an active GSSG-Rd pathway in the conceptus during organogenesis, and implicating an important role of the pyridine nucleotides in the restoration of GSH homeostasis in the developing rat conceptus during organogenesis.

Amiloride and the Na(+)/H(+) exchanger protein: mechanism and significance of inhibition of the Na(+)/H(+) exchanger (review)

Amiloride and its derivatives are important tools for studying NHE-1, the ubiquitous isoform of the sodium/hydrogen exchanger protein family. Three residues in putative transmembrane domains IV and IX have been implicated in amiloride binding and several models of the proposed amiloride-binding site have been reported. Though it has been shown that sodium ions and amiloride molecules interact at unique regions of the NHE-1 protein, physiological experiments reveal a competitive relationship between the two under some circumstances. The two binding sites are thus on closely related but distinct regions on the protein.

Hypokalaemic paralysis revealing Sjögren syndrome in an elderly man

A 73 year old white man presented with life threatening hypokalaemic paralysis requiring admission to an intensive care unit. Biochemical investigations showed severe hypokalaemia with hyperchloraemic metabolic acidosis, a spot urine pH of 6.5, and a positive urinary anion gap, establishing the diagnosis of distal renal tubular acidosis. Autoimmune tests revealed Sjögren syndrome as the underlying cause of the distal renal tubular acidosis. Full recovery followed potassium and alkali replacement. This dramatic presentation of Sjögren syndrome has not previously been reported in an elderly man.

Iodinated and fluorinated steroid 2'-aryl-[3,2-c] pyrazoles as potential glucocorticoid receptor imaging agents

We have synthesized several halogenated steroids as potential glucocorticoid receptor mediated imaging agents. These compounds are analogs of aryl-pyrazolo steroids, similar to the potent glucocorticoid, cortivazol. Compounds containing the halogens, iodine, bromine, and fluorine, as well as the E- and Z-iodovinyl side chain at the para position of 2'-phenyl-11 beta,17,21-trihydroxy-16 alpha-methyl-20-oxo-pregn-4-eno[3,2-c] pyrazole were prepared. They were tested as ligands for the glucocorticoid receptor by competition for the binding of [3H]dexamethasone and for glucocorticoid potency by the induction of alkaline phosphatase in HeLa cells. None of the iodinated steroids were good ligands for the glucocorticoid receptor or potent glucocorticoids. The bromo analog was only slightly better than the iodinated steroids as a ligand, and it had a potency in the HeLa cell assay about half that of dexamethasone. The fluoro analog good binding to the glucocorticoid receptor and was a very potent glucocorticoid, approximately seven times that of dexamethasone. Consequently, it appears that the fluoro steroid, 2'-(4-fluorophenyl)-11 beta,17,21-trihydroxy-16 alpha-methyl-20-oxo-pregn-4-eno[3,2-c] pyrazole, when labeled with 18F, would make an excellent glucocorticoid receptor-mediated imaging agent for positron emission tomography.

Four-week supplementation with a natural dietary compound produces favorable changes in body composition

The purpose of this study was to determine whether a natural dietary supplement produced favorable changes in body composition during a 4-week diet- and-exercise program. The active compound contains a patented combination of chromium picolinate, inulin, capsicum, L-phenylalanine, and other lipotropic nutrients. A double-blind, weight-loss intervention design was used. Participants were randomly assigned to either a diet/exercise/supplement group (n = 56) or a diet/exercise/placebo group (n = 67). Caloric intake was reduced to 1500 kcal/d and participants walked for 45 minutes, 5 days a week, to attain between 60% and 80% of predicted maximal heart rate. Analysis of covariance (ANCOVA) showed significant differences (P < .05) between groups in percent body fat, fat mass, and fat-free mass; no significant differences were found (P > .05) in body weight, body mass index, or energy intake. Independent t tests showed no significant differences (P > .05) in diet composition between groups. Results indicate that the addition of a natural dietary supplement during a 4-week diet-and-exercise weight-loss program accelerates the rate of body fat loss and helps maintain fat-free mass (lean tissue), thereby producing favorable changes in body composition.

Influence of intense sound exposure on glutathione synthesis in the cochlea

Previous studies have shown that depletion of endogenous glutathione (GSH) potentiates noise-induced hearing loss (NIHL), whereas replenishment of GSH attenuates NIHL (Yamasoba et al., Brain Res. 784 (1998) 82-90). Since these findings indicate an important role of GSH in protection from NIHL, we assessed the influence of intense sound exposure (broadband noise, 105 dB SPL, 5 h) on GSH and cysteine levels in the guinea pig cochlea using high performance liquid chromatography. GSH levels were significantly increased in the lateral wall 2 and 4 h post-exposure and returned to normal 6 h post-exposure. GSH levels in the sensory epithelium and modiolus did not show significant changes following noise. Cysteine levels were unchanged in any of the cochlear segments. For the cochlea as a whole, intense sound exposure did not significantly change GSH or cysteine levels throughout the 6-h measurement period post-exposure. These results indicate that GSH synthesis is markedly upregulated selectively in the lateral wall by noise exposure, presumably in response to the robust consumption of GSH, as it is utilized in scavenging reactive oxygen species.

Modulation of intracellular glutathione and cysteine metabolism in bovine oviduct epithelial cells cultured In vitro

The objective of this study was to determine how alterations in intracellular thiol levels of oviduct epithelium occur in response to chemical or environmental conditions that could result in oxidative stress. Bovine oviducts were classified as follicular (F) or luteal (L) according to the reproductive stage of the ovary. Epithelial cells were harvested from the ampulla (AMP) and isthmus (ISTH) region of each oviduct, suspended in culture medium, and then plated into collagen-coated culture plates and grown to confluency. Basal levels of intracellular cysteine (Cys) and glutathione (GSH) were determined in oviduct epithelial cells and found to range from 0.36 to 0.46 pmol/ microg protein for Cys and from 5.3 to 6.4 pmol/ microg protein for GSH. Oxidized Cys values ranged from 21% to 39% of total Cys, whereas the oxidized GSH levels observed were from 21% to 28% of total GSH except in luteal ISTH, where they were significantly lower (6%). Confluent cells were exposed to GSH-depleting agents, <FONT SIZE=-1>L-buthionine-S,R-sulfoximine (BSO) or diethyl maleate (DEM), at doses ranging from 10 to 5000 microM. Both compounds depleted GSH in a dose-dependent manner, and 500 microM concentrations were chosen for subsequent studies with each compound. Cys levels in BSO (500 microM)-treated oviduct epithelial cells were transiently elevated over control values during the initial 5-h incubation; there was then a decrease in Cys levels by AMP but not ISTH oviduct epithelial cells. BSO-treated oviduct epithelial cells displayed a continued depletion of GSH over the incubation period and by 24 h were depleted by 38% to 61%. These results demonstrate a difference in GSH turnover in oviduct epithelial cells associated with reproductive stage. Exposure to DEM (500 microM) caused a decline in both Cys and GSH levels, which were partially restored after DEM removal. In general, L-staged oviduct epithelial cells were observed to be more competent at replenishing thiol stores than F-staged oviduct epithelial cells. Results from this study suggest that reproductive stage and region influence intracellular oviduct epithelium thiol status and therefore may affect how this tissue responds to chemicals or environmental conditions leading to oxidative stress.

Effects of a potent melanocortin agonist on the diabetic/obese phenotype in yellow mice

OBJECTIVE

To test the hypothesis that a melanocortin agonist can reverse obesity and insulin resistance in mice overexpressing the agouti protein. EXPERIMENTAL MODEL: Mice overexpressing the agouti protein either by transgene introduction (beta-actin promotor) or by mutation (Ay).

DESIGN

NDPMSH was tested for pharmacokinetic suitability. NDPMSH at various doses was administered subcutaneously twice a day for 2-3 weeks.

MEASUREMENTS

Fur pigmentation, various fatness parameters (core temperature, fat pad weight and body weight), blood glucose and hormones, fatty acid synthase measurement.

RESULTS

NDPMSH caused fur pigmentation and core temperature changes, but failed to affect any metabolic parameters in agouti-dependent manner.

CONCLUSION

NDPMSH, as a representation melanocortin agonist, does not compete with agouti in reversing agouti-dependent metabolic effects. This suggests that 1) agouti works via a receptor other than a melanocortin receptor to mediate its metabolic effects, 2) agouti-dependent metabolic effects are mediated through melanocortin receptors but not via antagonism of these receptors, or 3) NDPMSH is pharmacodynamically an inappropriate molecule for these types of studies.

Urinary tract infections may trigger relapse in multiple sclerosis

Multiple Sclerosis (MS), a demyelinating disease of the central nervous system, is the most common neurological disease affecting young adults in North America and, in the majority of cases, is associated with accumulating disability. Urinary tract dysfunction affects up to 90% of the MS population, and urinary tract infections are encountered in up to 74% of the tested population. Viral infections have previously been shown to trigger acute exacerbation and it is our experience that urinary tract infection also commonly precedes relapse, and, when recurrent, is associated with neurologic progression. We present three case studies from our MS Clinic where recurrent UTI was associated with acute exacerbation and neurologic progression refractory to intravenous steroid treatment. Interferons, protein signaling molecules, have recently been found to play a role in acute exacerbation and disease progression in individuals with MS. Viral infections induce interferon release which may activate T cells to produce gamma-interferon. Interferon-gamma precipitates relapse and stimulates production of tumour necrosis factor-alpha, a cytokine directly toxic to oligodendrocytes. Bacterial infections similarly induce interferon release and may activate immune pathways that result in MS exacerbation and neurologic progression.