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Biomedical subjects

S Banks

Publications and source records attributed to S Banks.

12 recordsLinked to original sources
PubMed1992

N omega-amino-L-arginine, an inhibitor of nitric oxide synthase, raises vascular resistance but increases mortality rates in awake canines challenged with endotoxin.

Inhibitors of nitric oxide synthase (NOS) have been reported to increase mean arterial pressure in animal models of sepsis and recently have been given to patients in septic shock. However, controlled studies to determine the effects of these agents on cardiovascular function and survival in awake animal models of sepsis have not been reported. To examine the therapeutic potential of NOS inhibition in septic shock, we challenged canines with endotoxin (2 or 4 mg/kg i.v.) and treated them with either normal saline or N omega-amino-L-arginine (10 or 1 mg/kg/h), the most specific inhibitor available for the isoform of NOS implicated in septic shock. Endotoxemic animals treated with N omega-amino-L-arginine (n = 11) had higher systemic and pulmonary vascular resistance indices (SVRI and PVRI, p less than or equal to 0.033) and decreased heart rates (p = 0.009), cardiac indices (CI, p = 0.01), oxygen delivery indices (p = 0.027), and oxygen consumption indices (p = 0.046) compared with controls (n = 6). Moreover, N omega-amino-L-arginine increased mortality rates after endotoxin challenge (10 of 11 vs. 1 of 6 controls, p = 0.005). Administration of L-arginine did not improve survival or alter the cardiopulmonary effects of N omega-amino-L-arginine, which suggests that inhibition of NOS may not have been competitive. In normal animals, N omega-amino-L-arginine alone (n = 3) increased SVRI (p = 0.0008) and mean arterial pressure (p = 0.016), and decreased CI (p = 0.01) compared with saline-treated controls (n = 3), but, at the high dose, also produced neuromuscular rigidity and seizure-like activity that was not apparent in the endotoxemic model. Thus, the mortality rate from endotoxemia increased either because of NOS inhibition per se or because of properties unique to N omega-amino-L-arginine, or both.

Amino Acid Oxidoreductases↗
PubMed1992

UV light-induced reactivation of herpes simplex virus type 2 and prevention by acyclovir.

UV B light is a potent stimulus for inducing reactivation of latent herpes simplex virus (HSV) infections. Patients were enrolled in a double-blind placebo-controlled crossover trial to determine whether acyclovir can prevent UV light-induced HSV-2 recurrences. Twenty-four patients with a history of recurrent infection of perigenital sites (e.g., buttock, thigh) were exposed one to four times with 4 minimum erythema doses of UV light. Patients were given acyclovir 200 mg orally five times daily or matched placebo beginning 1 day before each exposure and continuing for 5 days after exposure. There were 13 UV-induced recurrences among 36 placebo treatments and 3 after 38 acyclovir treatments (P = .004). The mean time to recurrence (+/- SE) was 4.8 +/- 0.3 days. HSV-2 lesions developed primarily at the site of UV exposure. The cutaneous distribution and timing of UV-induced recurrences was consistent with a neural localization (dorsal root ganglia) of latent viral infection. This UV light model permits direct examination of events leading to HSV-2 recurrences in humans and can be used to evaluate approaches to prevention.

Acyclovir↗
PubMed1991

Prevention of ultraviolet-light-induced herpes labialis by sunscreen.

Sunlight exposure is reported by some patients to precede onset of recurrent herpes labialis. Ultraviolet (UV) B light is known to be a stimulus for the reactivation of herpes simplex virus (HSV) infections. We assessed the effect of a sunblocking agent on UV-light-induced reactivation of recurrent herpes labialis in a double-blind, placebo-controlled crossover trial. 38 patients were exposed on two separate occasions to four minimum erythema doses of UV light at an area of previous labial herpes recurrence. A solution containing sunscreen was applied to the lips before one exposure and a matched placebo before the other. After placebo and UV exposure, herpes labialis developed in 27 (71%) of the 38 patients, with a mean time to recurrence of 2.9 (SEM 0.2) days. In contrast, when sunscreen was applied before UV exposure, no lesions developed, but 1 of the 35 patients shed virus at the exposure site. We conclude that UV light is a potent stimulus for inducing reactivation of herpes labialis, and that application of sunscreen may be effective in the prevention of sunlight-induced recurrent infection.

Adolescent↗
PubMed1991

Loss of heterozygosity and mitotic linkage maps in the mouse.

Loss of heterozygosity is a significant oncogenetic mechanism and can involve a variety of mechanisms including chromosome loss, deletion, and homologous interchromosomal mitotic recombination. Analysis of H-2 antigen-loss variants from heterozygous murine cell lines provides an experimental system to estimate the relative contributions of different mechanisms for allele loss and to compare the chromosomal patterns of mitotic and meiotic recombination. Cytotoxic anti-H-2D antibodies and complement were used to isolate 161 independent target antigen-negative clones from H-2d/H-2b heterozygous cell lines; of these, 131 (84.5%) lost the allele encoding the target antigen. Allele-loss variants were typed and scored as either heterozygous or homozygous for six H-2D-proximal chromosome 17 markers and for one distal marker by restriction enzyme-site variations and Southern analysis. A single mitotic crossover could account for 50 clones (37%), with heterozygosity for at least one proximal marker and loss of heterozygosity for all markers distal to the putative recombination site. Eighty-two allele-loss variants (60%) were homozygous for all markers; the origin of these clones could be either chromosome loss or mitotic recombination between the centromere and the most proximal marker. Only 4 clones (3%) arose through more complex events such as multiple crossovers or deletion. A mitotic linkage map for mouse chromosome 17 was constructed, and the gene order deduced from somatic recombination was identical to that obtained by conventional transmission genetics. These results demonstrate that mitotic recombination is a common event leading to allele loss, in spite of the lack of evidence for frequent somatic pairing of homologous chromosomes. Mitotic mapping provides a defined system for comparison of mitotic and meiotic recombination and may lead to practical advances for elucidating somatic mechanisms of oncogenesis and for gene therapy in targeting mutations to specific sites through homologous recombination.

Alleles↗
PubMed1990

Staffing of forensic inpatient services in the United States.

Data on patient census, bed capacity, and staffing levels in state-operated forensic psychiatric inpatient programs in 1986 were collected from forensic mental health directors of the 50 states and the District of Columbia. Of the 75 programs identified, 54 were based in units within larger psychiatric hospitals and 21 in freestanding hospitals. For all programs, direct-care staff-patient ratios ranged from .35 to 4, with a mean of 1.3. The ratio of filled beds to bed capacity ranged from .5 to 1.54, with a mean of .95. Nearly a fourth of the programs were over capacity. A negative relationship between filled-bed ratios and direct-care staff-patient ratios was found.

Forensic Psychiatry↗
PubMed1990

Pseudomonas aeruginosa compared with Escherichia coli produces less endotoxemia but more cardiovascular dysfunction and mortality in a canine model of septic shock.

We investigated the effects of two different Gram-negative bacteria and radiation-induced leukopenia on endotoxemia, cardiovascular abnormalities, and mortality in a canine model of septic shock. Serial hemodynamics were measured in conscious dogs using radionuclide heart scans and thermodilution cardiac output catheters. Plasma endotoxin concentrations were determined with a chromogenic Limulus amebocyte lysate assay. Viable Pseudomonas aeruginosa or Escherichia coli implanted intraperitoneally produced concordant hemodynamic patterns of septic shock (p less than 0.01). Endotoxin concentrations were more than tenfold lower in dogs infected with P aeruginosa compared with E coli (p less than 0.0001). Despite lower endotoxin levels, P aeruginosa-infected dogs had a higher mortality (p less than 0.01), more severe hypotension (p less than 0.05), and greater depression of the left ventricular ejection fraction (p less than 0.05) than dogs with E coli sepsis. A nonlethal E coli challenge combined with leukopenia (induced by a nonlethal dose of radiation) resulted in a mortality of 60 percent (p less than 0.01) without greater cardiovascular dysfunction or higher endotoxin concentrations. These findings suggest that bacterial products other than endotoxin and host-related factors may be important contributors to the toxicity, cardiovascular instability, and mortality of Gram-negative septic shock. Quantitative determinations of plasma endotoxin are unlikely to correlate with the clinical severity of septicemia in heterogeneous patient populations infected with different Gram-negative organisms.

Animals↗
PubMed1989

Zidovudine in patients with human immunodeficiency virus (HIV) infection and Kaposi sarcoma. A phase II randomized, placebo-controlled trial.

STUDY OBJECTIVE: To evaluate the toxicity, effects on immune function, antitumor effects, antiretroviral effects, and pharmacokinetics of zidovudine therapy in patients with early human immunodeficiency virus (HIV) infection and Kaposi sarcoma. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: National Institutes of Health, a referral-based research institution (single site). PATIENTS: Physician-referred volunteer patients with HIV infection, Kaposi sarcoma, CD4+ lymphocyte counts greater than 0.2 x 10(9)/L, and no systemic symptoms or history of opportunistic infection. Of 41 patients enrolled, 4 had not met all entry criteria and were therefore not evaluable. INTERVENTIONS: Patients were randomized to one of four treatment groups for an initial 12-week treatment period: oral placebo (9 patients); zidovudine, 250 mg orally every 4 hours (9 patients); zidovudine, 0.5 mg/kg body weight intravenously every 4 hours (9 patients); and zidovudine, 2.5 mg/kg intravenously every 4 hours (10 patients). After at least 12 weeks of therapy at their assigned dose, patients were treated with oral zidovudine, generally 250 mg every 4 hours, with a mean 42-week follow-up. MEASUREMENTS AND MAIN RESULTS: Anemia and granulocytopenia were the major toxicities. Significant increases in platelet counts and declines in serum HIV antigen and IgG and IgM levels occurred in treated patients. Treated patients were more likely than those on placebo to clear HIV from the cerebrospinal fluid. There were no differences in tumor progression or CD4+ or CD8+ lymphocyte counts among the groups. CONCLUSIONS: Zidovudine was well tolerated and had antiretroviral activity in patients with early HIV infection and Kaposi sarcoma but it had no significant effect on the extent of Kaposi sarcoma or on immune function.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Determination of antibody response to influenza virus surface glycoproteins by kinetic enzyme-linked immunosorbent assay.

We modified an existing enzyme-linked immunosorbent assay (ELISA) to be able to use new spectrophotometers which can measure the rate of color development in microtiter wells. This new kinetic-based ELISA (KELISA) required only a single dilution of specimen rather than the multiple dilutions required with endpoint ELISA. In addition, 10- to 100-fold-less specimen was required to perform the KELISA than the ELISA. The level of serum or nasal wash antibody against surface glycoproteins of influenza A or influenza B viruses determined by KELISA was reproducible and correlated highly with the results of endpoint ELISA or hemagglutination inhibition tests. The difference between the KELISA rates, which indicated than an antibody response to infection had occurred, was defined and was analogous to a 2.2-fold rise in titer for serum and a 3.4-fold rise in titer for nasal wash determined by endpoint ELISA. The KELISA was similar to endpoint ELISAs in its ability to detect rises in antibody level in paired serum or nasal wash specimens obtained from volunteers who received live attenuated influenza A reassortant virus vaccines. By eliminating the need for multiple dilutions, the use of KELISA offers the advantage of increasing the number of assays that can be performed by the same personnel compared with endpoint ELISA, while it maintains sensitivity and specificity.

Adult↗
PubMed1988

Natural murine autoantibodies and conventional antibodies exhibit similar degrees of antigenic cross-reactivity.

Splenic B cells from normal and autoimmune mice were transferred to MHC-compatible xid recipients. Monoclonal antibodies were secreted by the transferred B cells in splenic fragment cultures. These antibodies were evaluated for reactivity and cross-reactivity against a panel of six autoantigens and two conventional antigens using an ELISA assay. The autoantibodies and conventional antibodies produced in splenic fragment cultures by normal DBA/2 and autoimmune NZB B cells expressed similar degrees of antigenic cross-reactivity. Previous studies have demonstrated that ELISA assays of splenic fragment culture supernatants detect antibodies with affinities of 5 x 10(6) M-1 or greater. We therefore also analyzed the cross-reactivity of monoclonal antibodies derived from hybridomas. This permitted an assessment of antibodies with lower binding affinities. Cross-reactivity was detected more frequently among these hybridomas. Consistent with our earlier observations, hybridoma antibodies specific for conventional antigens exhibited cross-reactivity with a frequency similar to that of antibodies specific for autoantigens.

Animals↗
PubMedDate not supplied

Psychosocial dimensions of epilepsy: a review of the literature.

The literature on psychosocial dimensions of epilepsy has been reviewed utilizing the framework developed by Dodrill et al. (Epilepsia 1980; 21:123-35). Factors considered were family background, emotional adjustment, interpersonal adjustment, vocational adjustment, financial status, adjustment to seizures, and medicine and medical management. The published studies highlighted a number of issues and sometimes rendered varying and contradictory conclusions. In general, epilepsy fosters certain reactions in family members. If negative, these reactions may be detrimental to the person with epilepsy. The association between specific emotional adjustment factors and epilepsy is not conclusive. Studies have been published which support as well as refute this association. Studies indicate that persons with epilepsy experience lower rates of marriage and more sexual difficulties than do nonepileptic persons. Studies report greater unemployment and underemployment in epileptic persons than in the population at large. Studies suggest that some persons with epilepsy manifest an attitude of nonacceptance of self. Some are reluctant to disclose their disability to others. The studies also indicate the presence of a discriminatory attitude by some nonepileptic persons toward epileptic persons. Several factors are associated with successful medical management of epilepsy. The emphasis in research studies with regard to psychosocial aspects of epilepsy focuses predominantly on individual deficiencies rather than on strengths and abilities.

Aggression↗