Possible role of nitric oxide in the development of L-2-chloropropionic acid-induced cerebellar granule cell necrosis

1. L-2-Chloropropionic acid (L-CPA) produces selective neuronal cell necrosis in rat cerebellum when administered orally at 750 mg kg-1 that is mediated in part through activation of N-methyl-D-aspartate (NMDA) receptors. Cerebellar granule cell death occurs between 30 and 36 h following L-CPA administration exhibiting a number of features in common with excitatory amino acid-induced cell death. We have used this in vivo model to examine the neurochemical processes following L-CPA-induced activation of NMDA receptors leading to neuronal cell death in the rat cerebellum. 2. The effects of a number of compounds which potently block nitric oxide synthase in vitro were examined on L-CPA-induced neurotoxicity 48 h following L-CPA dosing, to discover whether the neuronal cell death is mediated in part by excessive nitric oxide generation. Four inhibitors were studied, NG-nitro-L-arginine (L-NOARG), NG-nitro-L-arginine methyl ester (L-NAME), NG-iminoethyl-L-ornithine (L-NIO) and 3-bromo-7-nitroindazole (BrNI). 3. L-NAME (50 mg kg-1, i.p. twice daily) and BrIN (50 mg kg-1, i.p. twice daily) administration prevented the L-CPA-induced loss of granule cells which can reach up to 80-90% of the total cell number in rats treated with L-CPA alone. L-NOARG (50 mg kg-1, i.p. twice daily) and L-NIO administered at either 25 or 100 mg kg-1, twice daily did not produce any significant protection against L-CPA-induced neurotoxicity. 4. Both L-NAME and BrIN also prevented the L-CPA-induced increase in cerebellar water content and sodium concentrations. L-NIO when administered at the highest doses prevented the increase in cerebellar sodium concentration but not water content. L-NIO and L-NOARG were ineffective in preventing the L-CPA-induced increases in cerebellar water and sodium concentrations. 5. L-CPA-induced reductions in cerebellar aspartate and glutamate concentrations and increases in glutamine and GABA concentrations were prevented by L-NAME and BrIn, but not by L-NIO or L-NOARG. Also reductions in L-[3H]-glutamate binding to glutamate ionotrophic and metabotrophic receptors in the granule cell layer of rat cerebellum was prevented by L-NAME and BrIN, but not L-NIO or L-NOARG. 6. In conclusion, the neuroprotection offered by L-NAME and BrIN suggests that L-CPA-induced cerebellar granule cell necrosis is possibly mediated by or associated with excessive generation of nitric oxide. The inability of nitric oxide synthase inhibitors, L-NOARG and L-NIO to afford protection may result from their limited penetration into the brain (L-NIO) or rapid dissociation from the enzyme.

Anemia and the transition of nomadic hunter-gatherers to a sedentary life-style: follow-up study of a Kalahari community

Iron profiles of communities of hunter-gatherers and former hunter-gatherers conducted between 1969 and 1987 at Dobe in the Kalahari Desert of Botswana exhibited pronounced differences during periods of rapid culture change. The loss of good health and particularly the increase in anemia through time was attributed to notable changes in diet, although changes in mobility patterns were considered a secondary cause. In 1988 and 1989, studies were conducted at Kutse, also in the Kalahari Desert of Botswana, to ascertain the frequency of anemia at a recently sedentary community in which residents still relied primarily on wild animals for meat. Although not identical, the hematological presentation in 1989 was similar to that in 1988. The studies together suggest that our findings characterize the pattern of health and disease at Kutse, which is unrelated to any specific year or to diet. Additional measures of disease, specifically ESR (erythrocyte sedimentation rate) and oral temperatures, support an interpretation of anemia of chronic disease as the cause of hypoferremia at Kutse. Morbidity is high, in spite of adequate diets, because the residents are transitional from a nomadic to a sedentary lifestyle and from a relatively dispersed to an aggregated settlement pattern. These changes have introduced new health problems.

Characteristics of pregnant HIV-1 infected women in Europe. European Collaborative Study

There is a growing number of infected women in Europe and an increasing proportion of these have acquired their infection through heterosexual contact. Most infected women are of childbearing age and thus increasing numbers of children are at risk of acquiring infection. In this paper we examine the socio-demographic characteristics and trends in mode of acquisition of infection of 1690 infected women from 7 countries enrolled in the European Collaborative Study, a prospective multi-centre study of children born to women known to be HIV infected at or before the time of delivery. The majority of women were white, primiparae, married or cohabiting and born in Europe. Two-thirds had a history of injecting drug use (IDU), most commonly involving heroin. Although patterns of transmission varied by centre, there was a relative increase in heterosexual transmission over the study period. A history of needle-sharing among IDUs was common, but needle-sharing during pregnancy significantly declined between 1987 and 1994.

Detection of virus in vertically exposed HIV-antibody-negative children

BACKGROUND

HIV-infected mothers can transmit their infection to their children in utero or at delivery (vertical transmission). There have been cases of children who were reported as acquiring infection vertically and later clearing the infection. We report the frequency of this phenomenon in a European cohort study.

METHODS

In four centres of the European Collaborative Study of children born to HIV-infected mothers, 299 children became HIV-antibody-negative and 264 of these had been followed up with virus culture and PCR for viral DNA at least once.

FINDINGS

Nine of the 264 children were positive by virus culture or PCR, and subsequently seroreverted. Two of the nine tested virus-positive after they became antibody-negative. Six cases were virus-positive early in life and became negative thereafter, which is consistent with clearance of infection. The pattern was less clear in the other three. The nine cases had had their last virus test at age 16-101 months. All nine children had been bottlefed only. Eight had been delivered vaginally. The children had no HIV-related symptoms and received no anti-HIV treatments. Based on only those children who had two or more positive virological tests, we estimate that 2.7% (6/219) cleared or "tolerated" the virus.

INTERPRETATION

The detection of virus or viral DNA in "uninfected" children born to HIV-infected mothers was rare and was not associated with clinical disease or immunological abnormalities. The timing of samples will affect the documentation of clearance since, in uninfected children of HIV-positive mothers who cleared the virus, viraemia was intermittent. Current paediatric opinion is to inform parents of children who serorevert that the child is not HIV-infected.

The active site specificity of the Yersinia protein-tyrosine phosphatase

Yersinia protein-tyrosine phosphatase substrates have been synthesized employing an expedient methodology that incorporates phosphorylated non-amino acid residues into an active site-directed peptide. While the peptidic portion of these compounds serves an enzyme targeting role, the nonpeptidic component provides a critical assessment of the range of functionality that can be accommodated within the active site region. We have found that the Yersinia phosphatase hydrolyzes both L- and D-stereoisomers of phosphotyrosine in active site-directed peptides, with the former serving as a 10-fold more efficient substrate than the latter. In addition, this enzyme catalyzes the hydrolysis of a variety of aromatic and aliphatic phosphates. Indeed, a peptide bearing the achiral phosphotyrosine analog, phosphotyramine, is not only the most efficient substrate described in this study, it is also one of the most efficient substrates ever reported for the Yersinia phosphatase. Straight chain peptide-bound aliphatic phosphates of the general structure, (Glu)4-NH-(CH2)n-OPO3(2-) (n = 2-8), are also hydrolyzed, where the most efficient substrate contains seven methylene groups. Finally, a comparison of the substrate efficacy of the peptide-bound species with that of the corresponding non-peptidic analogs, reveals that the peptide component enhances kcat/Km by up to nearly 3 orders of magnitude.

Determining factors for the outcome of peripheral blood progenitor cells harvests

This is a pilot retrospective study to investigate the factors that may affect the collection of peripheral blood progenitor cells (PBPC). Sixty-nine PBPC harvests in 18 cancer patients (median age 39.5; 8 males and 10 females) were performed during marrow recovery after chemotherapy and hematopoietic growth factors. Median number of nucleated cells (MNC) collected were 13.3 (range 2.3-44.5) x 10(9) per session. Median CFU-GM was 362 colonies (range 63-1,720) per 500,000 MNC. Neither sex, body weight, diagnosis, nor the number of days into leukapheresis was significantly associated with MNC and CFU-GM. Older patients tend to have higher CFU-GM in the PBPC harvests (P = .0437). Higher WBC on the day of harvest is significantly associated with higher yield of MNC after leukapheresis (P < .0001). Patients without any evidence of disease have significantly higher yield of MNC than those having local/distant metastases with or without marrow involvement (P = .0302 and .0446). For patients with metastatic disease, those with bone marrow involvement tend to have higher CFU-GM than those without bone marrow involvement although the difference is not statistically significant (P = .0559). Those patients who have received only one, or three and more chemotherapy regimens have a higher yield of MNC than those who have only two previous chemotherapy regimens (P = .036 and .0324). The mechanism of PBPC mobilization is also discussed. In view of the limited patient number in this study, the results should be confirmed by larger studies.

[Increased production of nitric oxide in the immediate and late asthmatic responses in models of guinea pig experimental asthma]

Nitric oxide is produced in mammalian airways by constitutive and inducible nitric oxide synthase, and endogenous nitric oxide can be detected as exhaled gas. Patients with asthma have large numbers of airway epithelial cells and inflammatory cells that contain nitric oxide synthase, and nitric oxide levels in exhaled air are high during immediate asthmatic responses. To examine the dynamics of nitric oxide synthase in the tracheas of guinea pigs, cumulative dose-response studies of 5-HT were done on tracheal strips, in the presence or absence of arginine and its analogues. This assay indicated that relative the activity of nitric oxide synthase was greater 6 hr after the challenge than immediately after, which suggests that nitric oxide is involved in the pathogenesis of bronchial asthma attacks.

Use of polymerase chain reaction and quantitative antibody tests in children born to human immunodeficiency virus-1-infected mothers

The diagnosis of human immunodeficiency virus (HIV) infection in children born to HIV-infected mothers is complicated by the presence of passively acquired maternal antibodies, and exclusion of infection in these infants remains problematic. The use of genome detection by polymerase chain reaction (PCR) amplification and the quantification of anti-HIV-1 antibodies were examined as methods for early diagnosis. Blood samples were taken from 84 non-breast-fed infants of HIV-infected mothers in five Italian and Spanish centres, a subgroup of children enrolled in the European Collaborative Study (ECS) for whom clinical and immunological information has been documented from birth. Whole blood was added to glycigel cryopreservative, stored, and tested in the United Kingdom by a nested PCR method. Antibody to HIV-1 was detected and quantified by titration using a gelatin particle agglutination test. PCR sensitivity and specificity were assessed. Twenty-one of the 84 children tested were infected. The estimated PCR sensitivity ranged from 0% (95% CI 0-26%) on day 1, 57% (19-85) on day 7, to 63% (33-92) on day 30. The negative predictive value of PCR ranged from 85% (83-88) on day 0 to 98% (94-100) at 3 months of age. On average, the level of maternal antibody halved every 33 days (31-36.5) in uninfected children. Between 6 and 9 months of age, increases in antibody titres in infected children were not more informative than absolute levels. These findings suggest that antibody measurement may supplement genomic diagnosis and that this collection method provides an alternative to the use of dried blood spots.

The cyclic dilemma: organic, functional, and environmental interaction in a young teenager

This Grand Rounds considers an early-adolescent female who demonstrated a mixed clinical picture including rapid cycling of psychotic behavior. The case presents issues commonly faced in hospital practice and provides an example of the use of standardized instruments in assessment and monitoring treatment, as well as a discussion of issues germane to inpatient child and adolescent psychiatrists and related treatment team members.

The European Collaborative Study: clinical and immunological characteristics of HIV 1-infected pregnant women

OBJECTIVE

To describe the changing clinical and immunological characteristics and timing of diagnosis of HIV-infected pregnant women enrolled in the European Collaborative Study.

DESIGN

A prospective study of the mothers of children enrolled in the European Collaborative Study on children born to HIV-infected women.

SETTING

Twenty-one European centres in seven countries.

SUBJECTS

One thousand six hundred and ninety HIV-infected women and their 1754 deliveries.

RESULTS

The proportion of women in whom HIV infection had been diagnosed before pregnancy increased significantly over time, from 7% in 1984-1985 to 65% in 1994 (P < 0.001). The prevalence of breastfeeding, which was related to the timing of diagnosis, significantly declined over the study period. The mean CD4 count was 510 cells/mm3, and there was a significant decline in average CD4 count over the study period. Black women had a significantly lower CD4 count than white women. From survival analysis it is estimated that five years after delivery 14% of women will have died and 24% will have developed CDC stage IV disease.

CONCLUSIONS

Timing of diagnosis is of critical importance if mother-to-child transmission is to be reduced through avoidance of breastfeeding and zidovudine therapy and effective antenatal screening policies have become increasingly important. The rate of progression of maternal disease highlights the implications of HIV infection for their children, both infected and uninfected.

Implementation of the Patient Self-Determination Act in a community hospital

After extensive staff/community education, a New Jersey community hospital survey found good compliance with the Patient Self-Determination Act, but only 14.8 percent of patients had completed advance directives, and there was infrequent physician documentation.

Optimal Gabor filters for texture segmentation

Texture segmentation involves subdividing an image into differently textured regions. Many texture segmentation schemes are based on a filter-bank model, where the filters, called Gabor filters, are derived from Gabor elementary functions. The goal is to transform texture differences into detectable filter-output discontinuities at texture boundaries. By locating these discontinuities, one can segment the image into differently textured regions. Distinct discontinuities occur, however, only if the Gabor filter parameters are suitably chosen. Some previous analysis has shown how to design filters for discriminating simple textures. Designing filters for more general natural textures, though, has largely been done ad hoc. We have devised a more rigorously based method for designing Gabor filters. It assumes that an image contains two different textures and that prototype samples of the textures are given a priori. We argue that Gabor filter outputs can be modeled as Rician random variables (often approximated well as Gaussian rv's) and develop a decision-theoretic algorithm for selecting optimal filter parameters. To improve segmentations for difficult texture pairs, we also propose a multiple-filter segmentation scheme, motivated by the Rician model. Experimental results indicate that our method is superior to previous methods in providing useful Gabor filters for a wide range of texture pairs.

Chemoprophylaxis with oral ciprofloxacin in ovarian cancer patients receiving taxol

The purpose of this study was to review the clinical outcomes and cost of administration of a prophylactic antibiotic compared to G-CSF for the prevention of neutropenic morbidity associated with taxol. The study group was composed of 62 patients with ovarian cancer who received a 24-h infusion of a taxol-based regimen at doses less than or equal to 175 mg/m2 between June 1992 and April 1994. The records were retrospectively reviewed and the patients were grouped and analyzed according to the management of their myelosuppression. Group I patients (n = 29) were observed until their absolute neutrophil count (ANC) was less than 500/microliters and then were placed on ciprofloxacin 500 mg orally twice a day until their ANC was 1,000/microliters. Group II patients (n = 15) received G-CSF from Day 2 until the ANC was greater than 10,000/microliters beginning with their first cycle. Group III patients (n = 18) received their taxol regimen without either ciprofloxacin or G-CSF. Two hundred eighty-two taxol-based chemotherapy cycles were administered to these 62 patients. There was no statistically significant difference between the groups concerning disease status as measured by age, stage, performance status, dose intensity, or number of previous regimens. There were two episodes of febrile neutropenia in Group I and three episodes in Group II. Group III had 15 episodes of febrile neutropenia. The estimated cost of the different prophylactic regimens was $5,215.00 for Group I versus $104,000.00 for G-CSF in Group II. Within the three groups, there were 27 patients with an episode of febrile neutropenia (n = 20) or prolonged myelosuppression (n = 7) that were followed for an additional 104 taxol cycles. Twenty-four of these patients received G-CSF prophylaxis with intermittent ciprofloxacin and three received only ciprofloxacin. There were eight more episodes of febrile neutropenia in the patients receiving G-CSF. There were no additional febrile episodes on cycles prophylaxed with ciprofloxacin. There was no septic mortality. For patients receiving a 24 h infusion of taxol at doses less than 175 mg/m2, ciprofloxacin given through the ANC nadir may be effective in preventing febrile morbidity. A prospective randomized trial is underway to evaluate this approach.

T-cell lines derived from lesional skin of lichen planus patients contain a distinctive population of T-cell receptor gamma delta-bearing cells

Lichen planus is characterized by a dense infiltrate of T lymphocytes at the dermoepidermal junction. To determine the phenotypic and functional characteristics of the infiltrating lymphocytes, T-cell lines from normal and lesional skin from the same patients with lichen planus were established by culture with interleukin 2 followed by stimulation every 14 d with phytohemagglutinin and irradiated allogeneic feeder cells. Resultant T-cell lines were immunophenotyped by staining with monoclonal antibodies and their reactivity tested by determining their cytolytic activity to selected targets. T-cell lines from 13 lesional and nine normal biopsy specimens were studied. T-cell lines from normal skin were 61% CD4+ and 32% CD8+, whereas lines from lesional skin had significantly fewer CD4+ cells (13%) and more CD8+ cells (62%). T-cell lines from lesional skin contained a distinctive population of gamma delta T cells that was rarely present in lines derived from normal skin. We were able to culture gamma delta T cells out of the lesional skin of 12 of 13 patients. In these 12 patients, lesional T-cell lines were 17% gamma delta+ (range 2% to 47%). Only one T-cell line from normal skin contained significant numbers of gamma delta T cells. The gamma delta population from lesional skin was commonly V delta 1J delta 1+. These results suggest that CD8+ and TCR gamma delta+ T lymphocytes may be involved in the development or the maintenance of lichen planus.

Mycophenolate mofetil (RS-61443): preclinical, clinical, and three-year experience in heart transplantation

Mycophenolate mofetil (formerly known as RS-61443) is a morpholinoethyl ester of mycophenolic acid. Mycophenolic acid is a unique immunosuppressive agent because of its mechanism of action. By inhibiting the de novo pathway of purine synthesis, mycophenolic acid suppresses lymphocyte function much more than that of neutrophil, erythrocyte, and other rapidly dividing cell lines which can use the salvage purine synthesis pathway. Mycophenolate mofetil has been shown to be an effective immunosuppressive agent in both animal models and early human trials. This article describes the history, biochemistry, pharmacology, in vitro and in vivo effects, and clinical trials of myophenolate mofetil. In addition, previously unpublished 3-year follow-up of heart transplant recipients receiving mycophenolate mofetil is reported.

Laparoscopic cholecystectomy in England and Wales: results of an audit by the Royal College of Surgeons of England

The results of an audit of open and laparoscopic cholecystectomy conducted by the Comparative Audit Service of The Royal College of Surgeons of England are presented. Data were submitted by 124 consultant surgeons on 3319 attempted laparoscopic and by 227 consultant surgeons on 8035 open cholecystectomies performed in England and Wales during the 2 years 1990 and 1991. These were contrasted with 9322 attempted laparoscopic cholecystectomies reported in 21 series reported in the world literature between 1991 and 1992, and with five other nations' audit studies. Among attempted laparoscopic cases, conversion to an open procedure was necessary in 175/3319 (5.2%) of cases and overall mortality was 0.15% (5/3319). Major complications were reported in 2.1% and minor complications in 5.9% of cases. Bile duct injury was reported to be significantly more common after attempted laparoscopic cholecystectomy (11/3319, 0.33%) than after open cholecystectomy (4/8035, 0.06%) (95% confidence intervals -0.48 to 0.08), but it was not significantly different from that reported for laparoscopic cholecystectomy in the combined world literature (28/9322, 0.3%) (95% confidence intervals -0.19 to 0.25). Most systemic complications were significantly more common after open cholecystectomy. For open cholecystectomy, the mortality was 55/8035 (0.76%), with major complications reported in 3.2% and minor complications in 9.8% of patients. Adoption of the laparoscopic approach was associated with a four-fifths reduction in the mortality of cholecystectomy, and a 40% reduction in the overall complication rate when compared with the open operation. While laparoscopic cholecystectomy has an impressively low mortality and morbidity profile during the first 2 years of its introduction into the UK, prevention of bile duct injury is the most important issue to be addressed in all laparoscopic cholecystectomy training programmes.