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.

Replication and tropism of human immunodeficiency virus type 1 as predictors of disease outcome in infants with vertically acquired infection

In a series of 97 infants born to mothers who were seropositive for human immunodeficiency virus type 1 (HIV-1), 18 were identified as infected within the first 60 days of life on the basis of viral culture and polymerase chain reaction findings. We studied viral burden in vivo by quantitative polymerase chain reaction and the in vitro replication pattern of the HIV-1 infecting strain by culturing patient cells with normal phytohemagglutinin-stimulated peripheral blood mononuclear cells. According to the lag phase before p24 antigen detection and the level of p24 production on peripheral blood mononuclear cells, HIV-1 isolates from these patients were classified as rapid/high (R/H), slow/high (S/H), and slow/low (S/L). The pattern of HIV-1 replication in vitro was significantly associated with the viral burden in vivo; the range of HIV-1 copies per 10(5) peripheral blood mononuclear cells was 10 to 38, 44 to 314, and 360 to 947 in children with isolates of the S/L, S/H, and R/H types, respectively. Viral tropism was assessed by culturing patient cells under end-point dilution conditions with either CD4+ T-lymphocytes or monocyte-derived macrophages. We found that children with S/L isolates harbored mainly monocytotropic variants; all infants with S/H or R/H isolates had T-lymphotropic variants and, in 7 of 11 cases, monocytotropic or amphitropic variants. All children with R/H isolates had HIV-related symptoms by the age of 4 months, and five had acquired immunodeficiency syndrome by the age of 1 year. At 1 year of age, four and no infants with S/H or S/L isolates, respectively, had HIV-1-related symptoms (p < 0.001), and none had acquired immunodeficiency syndrome (p = 0.006).

The use of mycophenolate mofetil (RS-61443) in human heart transplant recipients

Mycophenolate mofetil is a potent inhibitor of de novo guanine nucleotide synthesis that selectively blocks lymphocyte proliferative responses. In animal models, mycophenolate mofetil has been shown to prolong allograft survival, reverse ongoing rejection, and induce strain-specific tolerance. To assess the safety and efficacy of mycophenolate mofetil in cardiac transplantation, 30 recipients with mild rejection were enrolled in an 8-week phase I trial. Mycophenolate mofetil in doses from 500 to 3000 mg/day orally was substituted for azathioprine, while baseline cyclosporine levels and corticosteroid doses were maintained. Rejection resolved in the majority of patients, with a significant decrease in mean biopsy score. By protocol, mycophenolate mofetil was discontinued in 4 patients due to persistent mild rejection, and in 4 patients due to progression to moderate rejection. The rate of progression to moderate rejection compared favorably with that observed in patients with mild rejection maintained on azathioprine without augmentation of immunosuppression. Significant increases were observed in hematocrit, total white blood cell count, and absolute neutrophil count. Absolute lymphocyte count remained unchanged. No nephrotoxicity or hepatotoxicity was observed. Gastrointestinal side effects prompted discontinuation of mycophenolate mofetil in one patient. Two major infections occurred. Mycophenolate mofetil remained well tolerated during long-term maintenance immunosuppression, with a rate of rejection similar to that in patients receiving azathioprine. We conclude that mycophenolate mofetil is safe and well tolerated in cardiac transplant recipients, is less myelosuppressive than azathioprine, and appears to be at least equipotent to azathioprine.

Etiology of hypoferremia in a recently sedentary Kalahari village

To determine the etiology of hypoferremia in recently sedentary hunter-gatherers, a community located in the Kalahari Desert of Botswana was studied. Iron profiles of 106 Basarwa (Bushmen, San) volunteers were examined. Hematocrits were measured in the field. The remaining blood was processed for transportation to a research medical laboratory for further studies. Subnormal serum iron values were present, depending on the subpopulation, in 50-52% of the volunteers. Transferrin saturation was subnormal in 35-49% of those tested. The absence of subnormal serum ferritin levels indicates that dietary iron deficiency is not the cause of the hypoferremia. Instead, serum ferritin was greater than 50 micrograms/l (a level indicative of anemia of chronic disease/inflammation) in 92% of the hypoferremic adult Basarwa. We suggest that by depriving microbes of needed iron, the frequency of the anemia of infections and chronic disease in this population might be a response to, and defense against, a chronically high pathogen load in a community that has not yet incorporated sanitation practices appropriate for sedentary aggregations.

Esophagogastric ring: why and when we see it, and what it implies: a radiologic-pathologic correlation

Schatzki first reported a ring-like structure at the esophagogastric mucosal junction in 1953. There is still no uniform agreement as to its exact location, etiology, or clinical importance. We found an esophagogastric ring in 15% to 18% of 22,368 patients having routine upper gastrointestinal examinations. It was present only in patients with cephalad displacement of the esophagogastric junction and only in those who had sharply and circumferentially marginated transition of esophagogastric mucosal junction. It is postulated that the esophagus shortens on vagal stimulation by contracture of the longitudinal esophageal muscle, which causes a mucosal infolding at the esophagogastric junction. In a small group of these patients, fibrosis apparently develops in this region and results in a fixed organic circumferential diaphragm, which may cause obstructive symptoms. These concepts affect therapeutic alternatives.

Alpha-1-protease inhibitor in bronchial asthma: phenotypes and biochemical characteristics

The prevalence of the different phenotypes of alpha 1-protease inhibitor (alpha 1PI) was investigated in a group of 90 asthmatic patients and compared with that of a control group of 240 individuals representing the general population. The M2M2 phenotype occurred more frequently in the asthmatic group (p = 0.015). Plasma samples of 51 of the asthmatic patients randomly selected from the different phenotype groups identified were studied for the absolute plasma values of alpha 1-PI and the inhibitory capacity of plasma for porcine pancreatic elastase, and compared with those from 21 nonasthmatic individuals of the M1M1 phenotype. Although the asthmatic patients had higher absolute alpha 1PI values (p = 0.04), the plasma elastase inhibitory capacity was markedly reduced compared with the nonasthmatic subjects (p = 0.01). The functional efficiency of alpha 1PI from asthmatic patients of the M1M1, M1M2, and M2M2 phenotypes was significantly decreased compared with that of the nonasthmatic M1M1 individuals. Functional deficiency of alpha 1PI may be important in the pathogenesis of the inflammatory process that characterizes bronchial asthma.

Concomitant intestinal adenovirus infection and pulmonary cytomegalovirus infection in children causing fatal enteritis and pneumonia

Three children in Bangladesh who presented with diarrhoea, cough, dyspnoea, fever, and signs of malnutrition and died in the hospital were shown at post-mortem examination to have both adenovirus infection of the intestine (by immunofluorescence) and cytomegalovirus infection of the lung (by immunoperoxidase staining). This finding of dual viral infections of the intestine and lung in patients with concomitant enteritis and pneumonia provides a basis for symptoms emanating simultaneously from these two organ systems.

A controlled trial of ganciclovir to prevent cytomegalovirus disease after heart transplantation

BACKGROUND

Because of the immunosuppression required, heart-transplant recipients frequently have complications caused by cytomegalovirus (CMV), including pneumonia, esophagitis, gastritis, and a syndrome of fever, hepatitis, and leukopenia. We undertook a controlled trial to evaluate the prophylactic administration of ganciclovir to prevent CMV-induced disease after heart transplantation.

METHODS

This randomized, double-blind, placebo-controlled trial was conducted at four centers. Before randomization, the patients were stratified into two groups: those who were seropositive for CMV before transplantation and those who were seronegative but who received hearts from seropositive donors. Ganciclovir was given intravenously at a dose of 5 mg per kilogram of body weight every 12 hours from postoperative day 1 through day 14, then at a dose of 6 mg per kilogram each day for 5 days per week until day 28.

RESULTS

Among the seropositive patients, CMV illness occurred during the first 120 days after heart transplantation in 26 of 56 patients given placebo (46 percent), as compared with 5 of 56 patients treated with ganciclovir (9 percent) (P less than 0.001). Among 37 seronegative patients, CMV illness was frequent in both groups (placebo, 29 percent; ganciclovir, 35 percent; P not significant). From day 15 through day 60, the patients who took ganciclovir had significantly fewer urine cultures positive for CMV, but by day 90 there was no difference. More of the ganciclovir-treated patients had serum creatinine concentrations greater than or equal to 221 mumol per liter (2.5 mg per deciliter) (18 percent vs. 4 percent in the placebo group), but those elevations were transient.

CONCLUSIONS

The prophylactic administration of ganciclovir after heart transplantation is safe, and in CMV-seropositive patients it reduces the incidence of CMV-induced illness.

Critical care nursing education at the baccalaureate level

Traditionally, only experienced nurses were selected to work in critical care. New graduates, however, are being hired for practice in critical care units despite controversy over the suitability of this setting for beginning practitioners. In this article, the authors describe the development of an undergraduate course in critical care nursing, outcomes of the course, teaching strategies used in both classroom and clinical settings, and effects of the course on the new graduate's practice.

Pediatric renal transplants--results with sequential immunosuppression

Cyclosporine has improved the results of renal transplantation. In 1984, we began using it as part of a sequential immunosuppression protocol (MALG, AZA, P, and delayed administration of CsA) in our pediatric renal transplant recipients. We studied the outcome of the 131 pediatric renal transplants (less than or equal to 18 years of age at transplant) performed at our institution between June 1984 and March 1991. We compared these results with the 144 similar transplants performed since January 1980 that did not involve CsA immunosuppression. In the sequential immunosuppression group, there were 97 primary (74%) (26 [27%] cadaver, 71 [73%] living donor [LD]) and 34 (26%) retransplant (23 [68%] CAD, 11 [32%]) recipients. Age at transplant (mean +/- SD) was 7.4 +/- 5.5. Overall, 1-year actuarial graft survival was 93%; 1-year patient survival was 100%. The mean number of hospital readmissions was 3.0 +/- 3.5; 26 (20%) were readmission-free. The mean number of rejection episodes was .87 +/- 1.3 per patient; 73 (56%) were rejection-free. Importantly, LD (vs. CAD) recipients had fewer rejection episodes (P = 0.06). In the first post-transplant year, the serum creatinine level was significantly lower in primary (vs. retransplant) recipients and in LD (vs. CAD) recipients (P less than 0.05). In the 144 patients not receiving CsA, there were 129 (90%) primary (27 CAD, 102 LD) and 15 (10%) retransplant (7 CAD, 8 LD) recipients. Age at transplant was 6.9 +/- 5.3 years. The 1-year actuarial graft survival rate was 82%; the 1-year patient survival rate was 94%. The mean number of hospital readmissions was 3.3 +/- 2.3; 5 (8%) were readmission-free. The mean number of rejection episodes was 1.2 +/- 1.5; 27 (45%) were rejection-free. There was no difference in the serum creatinine level based on donor source or transplant number. Sequential immunosuppression has significantly improved patient (P = 0.003) and graft survival (P = 0.004) rates. Comparing sequential vs. non-CsA immunosuppression, there was no difference in the number of readmissions (P = 0.47), number of rejection episodes (P = 0.17), or serum creatinine level. The number of rejection-free patients was significantly lower in LD (vs. CAD) recipients (P less than 0.05). There was no evidence of progressive deterioration in renal function in the sequential (vs. non-CsA) recipients.

Prostitutes and their clients: a Gambian survey

The social backgrounds and working behaviour of 248 prostitutes in urban and rural areas of The Gambia were investigated. Prostitutes were found to be highly mobile, moving frequently between a number of working locations in The Gambia and neighbouring Senegal, from which most of them originated. The educational level of prostitutes and the standard of living of their natal families were above average. Prostitutes worked on average four days a week and had between two and three clients a night. Condoms were used in up to 80% of contacts. 795 clients of prostitutes were interviewed and found to be on average of low educational and occupational status. Half were non-Gambian and most were currently travelling or living away from home.

HIV-2-induced immunosuppression among asymptomatic West African prostitutes: evidence that HIV-2 is pathogenic, but less so than HIV-1

Two hundred and forty-one prostitutes working in The Gambia were tested for retroviral infections and their immune system evaluated. Sixty-three were seropositive for HIV-2 only, five for HIV-1 only and six for both HIV-1 and HIV-2 (26.1, 2.1 and 2.5%, respectively). When compared to seronegative individuals, the 63 women infected with HIV-2 clearly had an abnormal immune system, with significantly lower CD4+ and higher CD8+ lymphocyte counts and percentages, lower CD4+:CD8+ ratios, lower CD25+ (activated) lymphocyte counts, and lower lymphocyte proliferation responses after stimulation with phytohaemagglutinin, purified protein derivative (PPD), Candida or pokeweed mitogen, and higher levels of neopterin and beta 2-microglobulin. However, when the HIV-2-seropositive prostitutes were compared with the five women infected with HIV-1, the former were less abnormal, with significantly higher CD4+ percentages and CD4+:CD8+ ratios and lower CD8+ percentages and counts. Immunological anomalies were seen in five women known to have been infected with HIV-2 for less than 17 months. Coinfection with HTLV-1 resulted in more severe immunological alterations than infection with HIV-2 alone.

Osteoblastoma response to chemotherapy

An 8-year-old boy had an osteoblastoma of the body of C2. After attempted excision, the tumor recurred rapidly and massively. The tumor shrank progressively after treatment with high-dose methotrexate, doxorubicin, and cisplatin. The patient has stopped treatment and been stable for 33 months. Surgical excision remains the treatment of choice for osteoblastoma. Chemotherapy may be useful in selected patients with a recurrent, aggressive tumor or in patients with surgically inaccessible disease.

Risk factors for second renal allografts immunosuppressed with cyclosporine

Second renal allograft survival rates are lower than those of primary allografts. For recipients immunosuppressed with azathioprine, prednisone, and Minnesota ALG (conventional immunosuppression), risk factors associated with decreased second graft survival have been identified: age greater than 40, cadaver donor, less than 6 months between primary graft loss and retransplantation, duration of primary graft function (6 months or 1 year, depending on the study), high peak panel-reactive antibody, number of human leukocyte antigen mismatches, and delayed graft function. In this study, we used a multivariate analysis to identify risk factors associated with decreased second graft survival in patients who did or did not receive cyclosporine. Results were compared with primary graft survival rates. Risk factors for patients receiving conventional immunosuppression were: (a) primary graft loss caused by rejection greater than or equal to 6 months (P = 0.01 vs. either rejection less than 6 months or nonimmunologic loss); (b) cadaver donor (P = 0.005 vs. living related); and (c) interval between primary graft loss and retransplantation of greater than or equal to 6 months (P = 0.05 vs. less than 6 months). For CsA, risk factors that most decreased second graft survival were: (a) primary graft loss caused by rejection less than 6 months (P = 0.11 vs. nonimmunologic loss); (b) conventional immunosuppression for the primary graft (P = 0.08 vs. CsA immunosuppression); and (c) a peak PRA of greater than or equal to 21 (P = 0.14 vs. peak PRA of 1-20). For second graft recipients immunosuppressed with CsA, primary graft loss to either rejection greater than 6 months posttransplant or nonimmunologic causes was not a risk factor for second graft survival. These data extend the recent reports of other investigators by identifying risk factors for retransplant recipients treated with CsA and by demonstrating that subgroups of patients in the retransplant population can be retransplanted without additional risk (i.e., their second graft survival rates are similar to primary graft survival rates). This may become more important if, in the future, organ distribution is based on graft survival data. If so, our data would support retransplantation in patients who are immunosuppressed with CsA, especially those who lost their primary graft to either rejection greater than or equal to 6 months posttransplant or nonimmunologic causes; who receive living related grafts; and who have a peak PRA of 1-20.

Tissue plasminogen activator: hospital experience

Tissue plasminogen activator (t-PA) is administered safely and efficiently in the treatment of acute myocardial infarction (MI). A study of 74 patients administered t-PA for acute MI associated with a low complication rate showed an acceptable patency rate, and a good outcome.

[Simultaneous removal of liver and pancreas does not have an effect on results of transplantation of these organs]

In a retrospective clinical study we compared the outcome after pancreas and liver transplantation when both organs were retrieved from the same donor to the outcome when only one or the other organ was retrieved. The results in this article demonstrate that simultaneous procurement of liver and pancreas grafts has no detrimental effect on the rate of technical failures, or allograft or patient survival after either pancreas or liver transplantation.

Expression of MHC class II antigens by conjunctival epithelial cells in trachoma: implications concerning the pathogenesis of blinding disease

In an attempt to understand the pathogenesis of corneal changes and conjunctival scarring in trachoma, which are responsible for blindness in some 7 million people worldwide, the surface expression of major histocompatibility complex class II antigens on conjunctival epithelial cells was sought in patients with different clinical features of the disease. Class II expression was significantly associated with active (inflammatory) trachoma, but an independent association with corneal pannus or conjunctival scarring could not be shown. Longitudinal data suggest that class II expression may antedate clinically active disease and persist after it has resolved.

The haematology of homozygous sickle cell disease after the age of 40 years

Haematological indices have been studied in 181 patients with homozygous sickle cell (SS) disease aged 40-73 years. Cross-sectional analyses in 5-year age bands indicated age-related decreases in HbF (males only), total haemoglobin and platelet counts. Longitudinal studies within individuals confirmed the downward age-related trend in haemoglobin and platelets and also revealed a falling reticulocyte count, most significant when expressed as absolute values. Total nucleated cells also fell although the decline was significant only in females. These observations are consistent with a progressive bone marrow failure which is not explained by the commonly occurring renal impairment in older SS patients since the changes persisted in analyses confined to patients with normal creatinine levels. The mechanism of this bone marrow failure is currently unknown.

Human IgE, IgG4 and resistance to reinfection with Schistosoma haematobium

A well recognized feature of the immune response to parasitic helminth infections, including schistosomiasis, is the production of large amounts of specific and nonspecific IgE1,2. Immunological pathways involving IgE can lead to damage to the developing schistosomulum and it has been suggested that responses involving IgE could have evolved as protection against helminth infections. There has been no epidemiological evidence to support this idea and the only significant IgE responses known in man are those involved in the pathogenesis of allergic disease. Here we measure serological response during reinfection with S. haematobium and demonstrate that IgE antibodies in man can be beneficial. Our results support the hypothesis that the slow build-up of IgE to high levels and the early production of IgG4 antibodies, which may block IgE pathways are responsible for delaying the development of protective immunity to S. haematobium.

HIV-2 infection among prostitutes working in The Gambia: association with serological evidence of genital ulcer diseases and with generalized lymphadenopathy

Three hundred and fifty-five prostitutes working in The Gambia were enrolled in a study of retroviral infections. Eight-seven (24.6%) were infected with HIV-2 only, two (0.6%) with HIV-1 only, four (1.1%) had sera showing double HIV-1/HIV-2 reactivity, and 37 (10.4%) were seropositive for HTLV-I. After allowing for socioeconomic and serological variables in a multivariate analysis, HIV-2 infection was associated with serological evidence of a previous episode of syphilis [a rapid plasma reagin (RPR) positive/Treponema pallidum haemagglutination assay (TPHA) positive; odds ratio (OR) = 2.18, 95% confidence interval (CI) = 1.19-3.98], with having antibodies against Haemophilus ducreyi (OR = 2.05, 95% CI = 0.89-4.70) or against HTLV-I (OR = 2.17, 95% CI = 0.91-5.19). HIV-2-seropositive prostitutes were three times more likely [17 out of 78 (22%) versus 15 out of 219 (7%), P less than 0.001] to have generalized lymphadenopathy than those who were seronegative. These data suggest that genital ulcer diseases may facilitate the transmission of HIV-2, and that HIV-2 rapidly induces the appearance of generalized lymphadenopathy in a substantial proportion of infected individuals.

A survey of New Jersey hospital ethics committees

A mail survey in 1988 of all 108 hospitals in New Jersey, and telephone follow-up in 1990, investigated the extent and structure of ethics committees with attention to the distinctions between prognosis, infant care review committees (ICRC) and general ethics committees (HECs). It disclosed that as of August, 1990, 74 hospitals had prognosis committees, 16 had ICRCs, and 64 had HECs. All types of committees tend to cluster in teaching hospitals and in hospitals with 200-500 beds. HECs average 13 members which include 4-5 physicians, 2-3 nurses, administrators and clergy (1-2 each), and fewer than one each for any other single profession. The primary purpose of HECS is to develop hospital ethics policy (96%), followed by educating hospital staff (80%), and providing counsel and support to physicians (67%). Case review with recommendation is provided by 54% of the HECs and 21% are involved in confirmation of prognosis.

Do not resuscitate policies of New Jersey hospitals

The do not resuscitate (DNR) policies of 100 New Jersey hospitals were investigated using a questionnaire to evaluate hospital characteristics, DNR documentation, decisionmaking, consent, satisfaction with present policies, and revision plans. Among responding hospitals, 78% indicated they had a policy, with--61% being established between 1984 and 1987. Twenty-two percent of hospitals with a DNR policy accepted oral orders, 39% accepted telephone orders, and 36% required written consent from a competent patient. Forty-nine percent of hospitals with a policy accepted qualified orders such as, "do not intubate." Sixty-two percent of responding hospitals were satisfied with their current policy. For 22 hospitals without a policy, 80% indicated dissatisfaction with their current practice. When hospitals with a DNR policy were compared to those without a policy, government supported hospitals were less likely to have a DNR policy than non-governmental hospitals (P = .04). Hospitals without a policy were more likely to perform "slow codes" than those with a policy (P = .007). A two-year follow-up survey found seven hospitals without DNR policies.

The catalytic domain of the neurofibromatosis type 1 gene product stimulates ras GTPase and complements ira mutants of S. cerevisiae

Sequencing of the neurofibromatosis gene (NF1) revealed a striking similarity among NF1, yeast IRA proteins, and mammalian GAP (GTPase-activating protein). Using both genetic and biochemical assays, we demonstrate that this homology domain of the NF1 protein interacts with ras proteins. First, expression of this NF1 domain suppressed the heat shock-sensitive phenotype of yeast ira1 and ira2 mutants. Second, this NF1 domain, after purification as a glutathione S-transferase (GST) fusion protein, strongly stimulated the GTPase activity of yeast RAS2 and human H-ras proteins. The GST-NF1 protein, however, did not stimulate the GTPase activity of oncogenic mutant ras proteins, H-rasVal-12 and yeast RAS2Val-19 mutants, or a yeast RAS2 effector mutant. These results establish that this NF1 domain has ras GAP activity similar to that found with IRA2 protein and mammalian GAP, and therefore may also regulate ras function in vivo.

The neurofibromatosis type 1 gene encodes a protein related to GAP

cDNA walking and sequencing have extended the open reading frame for the neurofibromatosis type 1 gene (NF1). The new sequence now predicts 2485 amino acids of the NF1 peptide. A 360 residue region of the new peptide shows significant similarity to the known catalytic domains of both human and bovine GAP (GTPase activating protein). A much broader region, centered around this same 360 amino acid sequence, is strikingly similar to the yeast IRA1 product, which has a similar amino acid sequence and functional homology to mammalian GAP. This evidence suggests that NF1 encodes a cytoplasmic GAP-like protein that may be involved in the control of cell growth by interacting with proteins such as the RAS gene product. Mapping of the cDNA clones has confirmed that NF1 spans a t(1;17) translocation mutation and that three active genes lie within an intron of NF1, but in opposite orientation.

A major segment of the neurofibromatosis type 1 gene: cDNA sequence, genomic structure, and point mutations

Overlapping cDNA clones from the translocation breakpoint region (TBR) gene, recently discovered at the neurofibromatosis type 1 locus and found to be interrupted by deletions and a t(17;22) translocation, have been sequenced. A 4 kb sequence of the transcript of the TBR gene has been compared with sequences of genomic DNA, identifying a number of small exons. Identification of splice junctions and a large open reading frame indicates that the gene is oriented with its 5' end toward the centromere, in opposition to the three known active genes in the region. PCR amplification of a subset of the exons, followed by electrophoresis of denatured product on native gels, identified six variant conformers specific to NF1 patients, indicating base pair changes in the gene. Sequencing revealed that one mutant allele contains a T----C transition changing a leucine to a proline; another NF1 allele harbors a C----T transition changing an arginine to a stop codon. These results establish the TBR gene as the NF1 gene and provide a description of a major segment of the gene.