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L Brown

Publications and source records attributed to L Brown.

At least 199 records · Page 11Linked to original sources
PubMed1993

Single and booster dose responses to an inactivated hepatitis A virus vaccine: comparison with immune serum globulin prophylaxis.

Pre- and postexposure prophylaxis against hepatitis A virus (HAV) infection with immune serum globulin (Ig) is only effective for 4-6 months. We compared the safety, tolerability and immunogenicity of a single i.m. injection of Ig with a single and booster dose of an inactivated hepatitis A virus vaccine (iHAV) in adults. Healthy volunteers (18-50 years) received a single Ig i.m. injection (n = 30), or iHAV i.m. (n = 15) at 0 and 24 weeks, or placebo (n = 4) at the same intervals. Anti-HAV seroconversion was measured by radioimmunoassay (RIA) and neutralizing antibodies by an antigen reduction assay. After Ig injection (0.06 ml/kg), anti-HAV seroconversion occurred in 100% of recipients at week 1, declining to 10% at week 12 and 0% by week 20. In contrast, after a single 25 ng dose, RIA seropositivity in iHAV vaccinees was 80% by week 2, reaching 100% by week 5 and persisted up to week 24, at which time anti-HAV geometric mean titres (GMT) were two fold higher than those seen at week 1 after Ig. Postbooster anti-HAV titres in iHAV recipients rose within 4 weeks to 73-fold greater than the peak GMT seen one week after Ig, and 400-fold higher than GMT at 12 weeks after Ig. Neutralizing antibody titres after iHAV followed a similar pattern, as observed for anti-HAV. iHAV was well tolerated; placebo and vaccine tolerability were indistinguishable, with no serious adverse experiences observed. In conclusion, active vaccination with a single iHAV dose may eventually replace Ig for pre-exposure prophylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Inactivated hepatitis A vaccine in childhood: implications for disease control.

The experience to date with the Merck inactivated hepatitis A vaccine in healthy children 2-16 years old is reviewed. Comparison of response to increasing doses indicates that an intramuscular dose of 25 units results in seroconversion of 99% of children by week 4 following a single dose. Antibody persistence rate is nearly 100% six months later, whether or not a second priming dose is given at week 8. This vaccine has proven highly immunogenic in children and has a favourable safety/tolerability profile. It should be useful for pre-exposure prophylaxis and control of hepatitis A, and should eventually replace immune globulin (Ig) for this indication.

Adolescent↗
PubMed1993

Safety, tolerability, and immunogenicity of an inactivated hepatitis A vaccine: effects of single and booster injections, and comparison to administration of immune globulin.

Hepatitis A virus (HAV) infection in adults is often symptomatic and disabling. The present article summarizes our experience with phase 2 studies of an inactivated hepatitis A virus vaccine. Pre- and post-exposure prophylaxis with immune globulin (IG) is only effective for 4-6 months. We compared the safety, tolerability, and immunogenicity of a single i.m. injection of IG with single and booster doses of an inactivated hepatitis A virus vaccine (iHAV) in adults. A total of 75 healthy volunteers (aged 18-50 years) were evaluated in two separate studies. The first included 15 volunteers who received 25 units iHAV i.m. at 0 and 24 weeks. The second, a randomly controlled study, consisted of three groups receiving 25 units iHAV i.m. at 0, 1, and 6 months, or at 0, 2, and 6 months, or 0.06 ml/kg IG i.m. given once. Anti-HAV seroconversion was measured by radioimmunoassay (RIA). After IG injection, anti-HAV seroconversion occurred in 100% of recipients at week 1, declining to 10% at week 12, and 0% by week 20. In contrast, after a single 25-unit dose, RIA seropositivity in iHAV vaccines was 73% by week 2, reaching 100% by week 5, and persisted in all up to week 24, at which time anti-HAV geometric mean titers (GMT) were 2-fold higher than those seen at week 1 after IG. Administration of a booster dose given 1 or 2 months after primary immunization did not significantly improve the quantitative anti-HAV response at 6 months as compared to the effect of the primary dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Anatomy of a trial: a historical view of the Monroe inactivated hepatitis A protective efficacy trial.

The performance of vaccine protective efficacy trials is often more complex than reports of final results suggest. The current article reviews the background, planning and preparations for the Monroe, NY, protective efficacy trial of a formalin-inactivated, alum-adjuvanted hepatitis A vaccine (VAQTA, manufactured by Merck Research Laboratories). The vaccine trial was carried out at Kiryas Joel, a Hasidic Jewish community which had experienced numerous annual outbreaks in a local environment with similarities to day-care centers. Careful communication, and cooperation of community leadership, a flexible technical resource team, and knowledge of an epidemic already ongoing in a sister community whose members were due to arrive for summer holidays, permitted rapid and efficient completion of the trial with a striking demonstration of protection after a single vaccine dose.

Clinical Protocols↗
PubMed1993

Worldwide experience with the CR326F-derived inactivated hepatitis A virus vaccine in pediatric and adult populations: an overview.

The worldwide experience to date with VAQTA, a highly purified formalin-inactivated hepatitis A vaccine containing alum-adjuvant, is reviewed. No serious adverse experience related to vaccination has been reported. The vaccine has proven highly immunogenic, with seroconversion detectable after a single dose in 90-99% of children 2-16 years old, and of adults under 77 kg (170 lb) body weight. There is a trend toward lower one-dose seroconversion rates with increasing age and with weight > 77 kg. Early seroconversion in the latter groups may require two 25-unit doses given 2, 4 or 8 weeks apart, or a higher priming dose. Seroconversion induced by this vaccine has been shown to signify protection from clinical hepatitis A disease. The few vaccines whose titers have waned to borderline levels responded anamnestically to a booster, suggesting that the vaccine induces an immune memory response and should provide long-term protection.

Adolescent↗
PubMed1993

Cardiac angiotensin receptors in experimental hyperthyroidism in dogs.

OBJECTIVE: The aim was to define the changes in angiotensin II receptors and the plasma renin-angiotensin system in experimental hyperthyroidism in dogs. METHODS: Hyperthyroidism was induced in dogs by subcutaneous injection of triiodothyronine (T3; 1 mg.kg-1 x d-1 for 14 d; group T); control dogs received saline (group C). Plasma angiotensin II (AII), angiotensinogen, renin activity and concentration, and angiotensin II receptors in left ventricle, right atrium, thoracic aorta, adrenal gland, and liver were measured. RESULTS: T3 treatment caused tachycardia, increased heart weight, hypertrophy of the circumflex and septal coronary arteries, increased plasma renin activity [C = 1.6(SEM 0.2), T = 9.8(2.8) ng angiotensin I.ml-1 x h-1], plasma renin concentration [C = 13.0(3.7), T = 34.5(5.6) ng angiotensin I.ml-1 x h-1], and plasma AII [C = 23(3), T = 104(5) pg.ml-1], while plasma angiotensinogen did not change. There were no significant changes in adrenal gland and right atrial angiotensin II receptor densities; increases were measured in the left ventricle [C = 0.33(0.06), T = 0.75(0.12) pmol.g-1 tissue], thoracic aorta [C = 0.19(0.02), T = 0.28(0.03) pmol.g-1 tissue], and liver [C = 8.4(1.2), T = 12.9(1.7) pmol.g-1 tissue]. The relative affinities of the left ventricular angiotensin II receptor for angiotensin peptides (obtained from displacement assays) were: Sar1, Ile8-AII > AII > angiotensin III > angiotensin I > hexapeptide > pentapeptide. CONCLUSIONS: Experimental hyperthyroidism in dogs results in activation of the plasma renin-angiotensin system and up regulation of left ventricular, aortic, and liver angiotensin II receptors.

Animals↗
PubMed1993

Renin-angiotensin system in thyroid dysfunction in rats.

Thyroid dysfunction produces marked cardiovascular responses; the renin-angiotensin system (RAS) is important in control of the cardiovascular system. We have measured changes in the plasma RAS and in angiotensin II (AT) receptors in experimentally hyperthyroid, euthyroid, or hypothyroid rats. Hyperthyroidism activated the plasma RAS, increasing plasma angiotensinogen by 85% after 7-day triiodothyronine (T3) treatment, plasma renin activity (PRA) by 47% and concentration by 52%, and plasma AT by 1.250%. Hypothyroidism reduced plasma angiotensinogen by 71%, PRA by 73%, and plasma AT by 81% without altering plasma renin concentration (PRC). Plasma aldosterone was reduced by 39% in hyperthyroid rats and by 95% in hypothyroid rats. AT receptors were characterized in heart, liver, adrenal gland, and kidney. Cardiac, liver, and kidney AT receptor densities increased in hyperthyroidism by 73, 113, and 75%, respectively; adrenal gland receptor density decreased by 39%. Similar results were observed in hypothyroidism except that adrenal gland receptor density was markedly increased by 205%. AT receptor subtypes were characterized in ventricular homogenates by the selective antagonist losartan. Hyperthyroidism markedly increased AT2-subtype density by 204% in left ventricle, and by 304% in right ventricle and decreased AT1-subtype density by 38% and 31% in left and right ventricles, respectively. AT2-subtype density increased by 168% in hypothyroid rats; AT1-subtype density was unchanged. Thyroid dysfunction causes significant changes in the RAS and in AT receptor density, especially of the AT2 subtype. Although a physiological function has not yet been reported for AT2 receptors, our results suggest that selective AT2-receptor antagonists may prove therapeutically useful in treatment of cardiovascular disease in thyroid dysfunction.

Adrenal Glands↗
PubMed1993

Growth, nitrogen metabolism, and cardiac responses to clenbuterol and ketoclenbuterol in rats and underfed cattle.

Two beta-adrenoceptor agonists, clenbuterol and ketoclenbuterol, were examined for their effects on growth and cardiac tissue. In female rats, clenbuterol caused a 48% increase in weight gain (P < .05), with improved feed efficiency (26%; P < .1) and increased muscle mass (9%; P < .1). Ketoclenbuterol had less effect on weight gain (30%) and feed efficiency (16%) and did not increase muscle mass. Next we studied the adverse cardiovascular effects of these compounds. Neither drug increased the force of contraction of isolated rat ventricular papillary muscle. Clenbuterol was potent at causing an increase in the rate of contraction of isolated rat atria, and when fed to cattle over 2 d, the drug caused heart rate to increase by 92 to 117%. In contrast, ketoclenbuterol was not a potent stimulator of atrial rate in the rat, and in cattle it caused a smaller increase in heart rate than clenbuterol (12 to 27%). Finally, cattle that were underfed to simulate dry-season tropical pasture conditions were treated with clenbuterol or ketoclenbuterol for 35 d. Ketoclenbuterol caused no beneficial changes in N metabolism. The results obtained with clenbuterol were equivocal, and might have been confounded partly by the refusal of some treated animals to eat all the feed offered. Although clenbuterol did not cause a reduction in total urinary N output relative to control animals, marked reductions in plasma urea concentrations and in urea synthesis were observed (23 to 53%; P < .001). We conclude that ketoclenbuterol is not effective for attenuation of dry-season protein loss in cattle. Clenbuterol seems to be less effective in underfed cattle than in well-fed cattle, and further evidence is required to judge whether compounds of this nature are likely to benefit tropical cattle under harsh grazing conditions.

Adrenergic beta-Agonists↗
PubMed1993

Pregnancy related coronary artery dissection: a case report and collective review.

There have been 31 patients with pregnancy related coronary artery dissection reported in the medical literature. We report a case of both right and left coronary artery dissection in a postpartum patient. A collective review of the clinical course, risk factors, and treatment specific mortality rates of coronary artery dissection in near term and postpartum females is discussed. The mean age was 33, the mean parity was 2.7, and the mean time span was 20 days postpartum. Twenty-two percent had known risk factors for coronary artery disease. Eighty-four percent involved the left anterior descending artery. Overall mortality was 66%. Of the patients that were alive on admission, 61% were treated medically (n = 11) with a 64% mortality; 39% were treated surgically (n = 7) with a 0% mortality. We conclude that pregnancy related coronary artery dissection occurs in otherwise healthy women near term or within three months postpartum. Multiparity and advanced maternal age may be risk factors. Early diagnosis and prompt surgical treatment may improve outcome.

Adult↗
PubMed1992

The Crithidia fasciculata CRK gene encodes a novel cdc2-related protein containing large inserts between highly conserved domains.

A gene (CRK) encoding a cdc2-related protein has been identified in the trypanosomatid Crithidia fasciculata. CRK has a high degree of sequence identity with the human cdc2 gene and contains the sixteen amino acid PSTAIR motif, characteristic of p34cdc2 protein-serine/threonine kinases, with four amino acid substitutions in the motif. In addition, two inserts of more than sixty amino acids have been found between conserved domains of this putative protein-serine/threonine kinase. CRK is a single copy gene and is expressed on a 3.8 kb mRNA. Anti-CRK antibodies detect a 53kDa protein in extracts of C.fasciculata in agreement with the size predicted from the nucleotide sequence of the cloned gene. These antibodies also recognize proteins of 48 and 60 kDa in extracts of the trypanosomatid Leishmania tarentolae. Antibodies against the human PSTAIR peptide detect the p34cdc2 protein in human nuclear extracts but fail to detect a 34 kDa protein in C.fasciculata extracts. These results suggest that novel higher molecular weight forms of the cdc2 protein family may be involved in cell cycle control in trypanosomes.

Amino Acid Sequence↗
PubMed1992

HEN1 and HEN2: a subgroup of basic helix-loop-helix genes that are coexpressed in a human neuroblastoma.

An important family of regulatory molecules is made up of proteins that possess the DNA-binding and dimerization motif known as the basic helix-loop-helix (bHLH) domain. The bHLH family includes subgroups of closely related proteins that share common functional properties and overlapping patterns of expression (e.g., the MyoD1 and achaete-scute subgroups). In this report we describe HEN1 and HEN2, mammalian genes that encode a distinct subgroup of bHLH proteins. The HEN1 gene was identified on the basis of cross-hybridization with TAL1, a known bHLH gene implicated in T-cell acute lymphoblastic leukemia. In situ fluorescence hybridization was used to localize the human HEN1 gene to chromosome band 1q22. HEN1 and HEN2 are coexpressed in the IMR-32 human neuroblastoma cell line, and they encode highly related proteins of 133 and 135 residues, respectively, that share 98% amino acid identity in their hHLH domains. These data imply that the bHLH protein subgroup encoded by HEN1 and HEN2 may serve important regulatory functions in the developing nervous system.

Amino Acid Sequence↗
PubMed1992

A controlled trial of a formalin-inactivated hepatitis A vaccine in healthy children.

BACKGROUND: Although inactivated hepatitis A vaccine is known to be well tolerated and immunogenic in healthy children and adults, its efficacy has yet to be established. METHODS: To evaluate the efficacy of the hepatitis A vaccine in protecting against clinically apparent disease, we conducted a double-blind, placebo-controlled trial in an Hasidic Jewish community in upstate New York that has had recurrent outbreaks of hepatitis A. At the beginning of a summer outbreak, 1037 healthy seronegative children 2 to 16 years of age were randomly assigned to receive one intramuscular injection of a highly purified, formalin-inactivated hepatitis A vaccine or placebo. A case was defined by the presence of typical signs and symptoms, a diagnostic increase in IgM antibody to hepatitis A, and a serum concentration of alanine aminotransferase at least twice the upper limit of normal. Cases occurring greater than or equal to 50 days after the injection were included in the evaluation of efficacy. The children were followed for a mean of 103 days. RESULTS: A total of 519 children received vaccine, and 518 received placebo. The vaccine was well tolerated, with no serious adverse reactions. From day 50 after the injection, 25 cases of clinically apparent hepatitis A occurred in the placebo group and none in the vaccine group (P less than 0.001), confirming that the vaccine had 100 percent protective efficacy. Before day 21, seven cases occurred in the vaccine group and three cases in the placebo group. After that time, there were no cases among vaccine recipients and 34 cases among placebo recipients. CONCLUSIONS: The inactivated purified hepatitis A vaccine that we tested is well tolerated, and a single dose is highly protective against clinically apparent hepatitis A.

Adolescent↗
PubMed1992

Serum triglyceride and insulin levels are associated with erythrocyte sodium-lithium counter-transport activity in normoglycaemic individuals.

The relationship between erythrocyte sodium-lithium counter-transport activity, serum insulin, lipids and demographic factors was examined in 93 normoglycaemic predominantly normotensive individuals with mild fasting hypercholesterolaemia (greater than 5.2 mmol/l). The major significant univariate correlates of sodium-lithium counter-transport activity were fasting serum triglycerides, HDL cholesterol, the ratio of fasting glucose: insulin, apo A1, alcohol consumption and apo B. Stepwise multiple regression analysis revealed 24% of the variability in sodium-lithium counter-transport activity could be accounted for by independent contributions of fasting serum triglycerides, alcohol consumption, the fasting glucose/insulin ratio and apo A1 and ANOVA confirmed a significant relationship with fasting insulin measures that was independent of serum triglycerides (P less than 0.05). The relationship between erythrocyte sodium-lithium counter-transport activity and concentrations of serum triglycerides, HDL components, insulin and additionally alcohol consumption, could reflect the influence of those variables on erythrocyte structure and function.

Alcohol Drinking↗
PubMed1992

The translocation (1;14)(p34;q11) in human T-cell leukemia: chromosome breakage 25 kilobase pairs downstream of the TAL1 protooncogene.

Nearly 30 percent of patients with T-cell acute lymphoblastic leukemia (T-ALL) exhibit a tumor-specific rearrangement of the TAL1 gene (also called TCL5 or SCL). These rearrangements are generated by either local DNA deletion or a (1;14)(p34;q11) chromosome translocation, and they typically result in structural alterations of the TAL1 transcription unit. In this report we present a molecular characterization of the t(1;14)(p34;q11) from a T-ALL patient. As a consequence of the translocation, TAL1 is transposed from its normal position on chromosome 1 into the T-cell receptor alpha/delta chain locus on chromosome 14. Unlike previous cases, the chromosome 1 breakpoint in this patient did not disrupt the continuity of the TAL1 transcription unit, but instead occurred approximately 25 kilobase pairs (kb) downstream of TAL1. This observation suggests that malignant alteration of TAL1 can be mediated by long-range cis-activating mechanisms that are triggered by DNA rearrangement at a distant site. Genes Chrom Cancer 4:211-216 (1992).

Base Sequence↗