Search PubMed⌕ Search

Biomedical subjects

L Greenberg

Publications and source records attributed to L Greenberg.

At least 73 records · Page 4Linked to original sources
PubMed1979

HLA-Dw antigens in unrelated juvenile, insulin-dependent diabetics.

Forty-one unrelated juvenile, insulin-dependent diabetics have been HLA tissue typed for A, B and Dw anitgens and compared with a normal control population. We have found statistically significant increases in the frequencies of B8, B18, and Dw3, and significant decrements in the frequencies of B7, B12 and Dw2. The log-linear modeling technique was used to study the association of JIDD with Dw3 and B8 antigens. We confirmed that the B8 excess seen in diabetics is secondary to the excess of Dw3. The decrements of B7, B12 and Dw2 could reflect an association of these antigens with a protective factor for the disease, or could be due to an artifact. The latter possibility was excluded for B7 and Dw2 by adjusting for the excess antigen frequencies. These findings suggest that the associations between the HLA and diabetes are compatible with the existence of genes which are concerned with the pathogenesis of the disease and are closely associated with the D locus of the major histocompatibility system.

Adolescent↗
PubMed1979

Age-related alterations in the development of adrenergic denervation supersensitivity.

The density of beta-adrenergic receptors in the central nervous system exhibits marked age-related changes. In general, there is an initial increase in receptors soon after birth followed by a decline with advancing age; the specific pattern of the development and loss of receptors is dependent upon the brain area. The ontogenetic increase in the density of adrenergic receptors coincides temporally with the development of responsiveness to catecholamines but can proceed without an adrenergic innervation. This suggests that the biosynthesis of receptors is genetically predetermined and does not require an adrenergic input for initiation. Decreasing adrenergic activity produces an increased number of beta-receptors and a supersensitive response to adrenergic agonists. The decline in beta-receptors with advanced age appears to be related to this phenomenon of denervation supersensitivity since certain aged tissues have a diminished capacity to develop an increased number of receptors in response to a reduced sympathetic input. We conclude that the decline in beta-adrenergic receptors with age may explain the age-related decrease in the sensitivity of adenylate cyclase to catecholamines, and, consequently, the reduced physiological response to adrenergic stimuli. The mechanism for this loss of receptors may be the inability of aged tissue to develop a supersensitivity response in reaction to diminished sympathetic activity.

Adenylyl Cyclases↗
PubMed1978

Serratia marcescens in human affairs.

Serratia marcescens, a ubiquitous, essentially saprophytic bacterium with a predilection for starches, has played a significant role in human affairs. Its notoriety has been occasioned by a blood-red pigment liberated by the organism during its metabolic activities that has been mistaken for fresh blood. In early Greek and Roman history, such "bloody" episodes were viewed as manifestations of divine destiny; by the Middle Ages in Europe they coincided with the development of church doctrine regarding the holy sacraments and had a far more sinister effect. In numerous instances between 1300 and 1500 A.D. host wafers developed a "bloody" appearance and led to the mass slaughter of Jews, who were accused of destructive attempts against the Eucharist. In our time, Serratia marcescens has been shown to possess significant endotoxic activity and can no longer be regarded as a harmless nuisance. It has been implicated in a wide range of human infections, particularly hospital-associated infections, of varying degrees of severity and including fatal antibiotic-resistant septicemias.

Bread↗
PubMed1978

Program for the expansion and improvement of biologics production and control in Latin America.

The production and control of biologicals sufficient to meet the needs of the countries in the Americas has been of basic concern to the Pan American Health Organization for many years. This is evidenced by the Ten-Year Health Plan for the Americas, drawn up in Santiago, Chile in 1972 by the Health Ministers of the Americas, in which the goal of making the Region self-sufficient in all of the essential immunizing agents within a ten-year period, was established. At present only Canada and the United States are more or less self-sufficient in this regard. All of the others are, to a greater or lesser degree, dependent on imports. In PAHO's present program the greatest emphasis is being placed on the development of effective control systems, particularly at the national level. The steps taken to achieve this goal and the progress to date are outlined.

Americas↗
PubMed1977

The effect of ethanol and bile on electrolyte movement across canine proximal duodenal mucosa.

The existence of a gastric mucosal barrier, controlling H+ N+ flux has been well established. The disruption of this barrier by ethanol and bile has also been confirmed. This study was designed to investigate the effect of ethanol and bile on the duodenal mucosa, which, as we have shown, is similar to gastric mucosa in that there is H+, Na+ flux. In 10 dogs, duodenal explants with an intact blood supply were placed within lucite chambers. Under basal conditions there was H+ insorption and Na+ exsorption. Neither bile nor ethanol caused increased H+ Na+ flux. Acute erosions did not develop in the proximal duodenum, as has been shown to occur when bile or ethanol is instilled into the stomach. These studies, therefore, demonstrate that although H+ Na+ occurs across the duodenal mucosa, bile or ethanol do not cause changes in ionic flux and acute erosions do not develop.

Animals↗
PubMed1976

Effects of imipramine and methylphenidate on perceptual-motor performance of hyperactive children.

Perceptual-motor effects of imipramine and methylphenidate were evaluated in a double-blind study of 47 hyperactive children. No effects were found for imipramine, although methylphenidate improved performance on several tests. Improvement due to methylphenidate was not related to base-line scores. A discriminant function was computed to compare baseline perceptual-motor scores of the hyperactive and 41 normal children. Only half of the hyperactive children were clearly discriminated from normal children by the discriminant function. The digit-span test, which was not sensitive to methylphenidate, effectively discriminated hyperactive from normal children.

Adolescent↗
PubMed1975

Field trials of a gonococcal vaccine.

Several small, well controlled field trials with a gonococcus vaccine have been initiated. The results to date indicate that the vaccine elicits only mild reactions in humans, and that it will produce antibodies of possible significance in over 90 per cent of vaccines. Its value in preventing gonorrhea has yet to be established. Studies towards this end are now being considered.

Adolescent↗
PubMed1975

Laboratory control of biological products in Latin America.

The manufacture of safe effective biological products in sufficient quantities to protect the entire population presents many problems in Latin America. The best way of ensuring such production would be to establish thorough control testing mechanisms. Ideally, no regulatory program should be considered complete without three tiers of controls: "in-process" production controls; "internal" controls by the manufacturer that monitor the production section; and "national" controls by the government that monitor the manufacturer. Although the standards maintained by some biologicals manufacturing centers in Latin America are very high, no country has yet established a full-fledged three-level control system of this kind. However, two countries have decided to employ such a system and are now close to achieving that goal. Perhaps the most essential facility in any national control program is the National Biologics Control Laboratory. This laboratory must be effectively organized, properly staffed, and backed by strong implementing legislation enabling it to perform its assigned tasks. In the past, lack of such a facility has created serious problems for biologicals manufacturing efforts in Latin America. Aware of this, a number of countries are now in the process of setting up and developing effective national laboratories of this kind

Biological Products↗
PubMed1975

Effect of aspirin on ionic movement and acid hydrolase activity of explants of canine antral and duodenal mucosae.

Lucite chambers, applied to antral and proximal duodenal mucosae with blood supply intact, were used to compare ionic flux and the total, labilized activity of several acid hydrolases including cathepsin D, alpha and beta-galactosidase, beta-N-acetyglucosaminidase, arylsulfatase, and acid phosphatase. Insorption of H+ ion by the antrum is increased by the application of aspirin-acid-salt solution, which also stimulates acid hydrolase activity; acute erosions develop very rapidly. On the other hand, H+ ion is much more rapidly removed from chambers applied to the duodenal mucosa, isolated by the chamber from bile and pancreatic secretions. The same aspirin-acid-salt solution reduces net H+ ion loss from the duodenal chamber, depresses levels of the acid hydrolases, and no ulcers develop.

Acetylglucosaminidase↗
PubMed1973

Assay of typhoid vaccines with Salmonella typhosa-Salmonella typhimurium hybrids.

Salmonella typhimurium hybrids expressing the S. typhosa antigens 9, d, and Vi were constructed by genetic crosses with an S. typhosa Hfr donor. The hybrids retained the same degree of mouse virulence as their S. typhimurium parent strain, the minimum lethal dose being less than 50 organisms when tested either in C(57) black mice or Swiss white mice. Vaccination of the Swiss white mice with S. typhosa Ty2 vaccines prepared by acetone treatment, alcohol treatment, or heat-killing conferred significant protection against challenge by the hybrid strains but not against their S. typhimurium parent. Both the acetone-treated and alcohol-treated typhoid vaccines were markedly more protective than the heat-killed, phenol-preserved vaccine.

Animals↗