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Biomedical subjects

A R Rabson

Publications and source records attributed to A R Rabson.

At least 19 recordsLinked to original sources
PubMed1992

Use of the polymerase chain reaction mismatch technique to identify the HLA-DQw8 allele in patients with insulin-dependent diabetes mellitus.

The allelic forms of the HLA-DQB gene have been recognized as susceptibility markers of type 1 diabetes mellitus. One of these alleles, the DQw3.2 (DQw8), accounts for the well-documented association of the DQw3 locus with the disease. This report describes a method using the polymerase chain reaction mismatch technique to amplify the three different DQw3 allele sequences in 26 insulin-dependent diabetic patients. Primers were designed that differed only at one base at the growing end of their sequences. Using a common oligonucleotide primer located downstream in the first domain of the DQB gene and three other primers located at the other end of the sequence being amplified, it was possible to identify and distinguish the DQw8 allele from the other two closely related alleles (DQw7, DQw9). This method, which could be useful in excluding HLA-related susceptibility to diabetes mellitus, is rapid and nonisotopic, and indeed could be adapted to investigate any DNA sequence polymorphism.

Alleles↗
PubMed1992

Rapid detection and species identification of mycobacteria in paraffin-embedded tissues by polymerase chain reaction.

The sensitivity and specificity of the polymerase chain reaction (PCR) in the detection of mycobacteria in paraffin-embedded tissues and in crude lysates of mycobacterial cultures were assessed. Sections of formalin-fixed, paraffin-embedded tissues were deparaffinized and then subjected to a simple proteinase K and boiling lysis procedure. These preparations were used directly for PCR amplification of the 383 bp segment of the gene encoding the 65 kDa mycobacterial surface antigen. Crude lysates of mycobacteria were used as positive controls. The specificity of the PCR products was confirmed by Southern blot using a region-specific digoxigenin-labeled oligonucleotide probe and chemiluminescent detection. The 383 bp diagnostic fragment was visualized in 11 of 12 acid-fast bacilli (AFB) stain/culture-proven-positive blocks. Crude lysates of mycobacteria were detected to a sensitivity of approximately 80 organisms. Amplified fragments from paraffin-embedded tissues and mycobacterial cultures of M. tuberculosis, M. avium-intracellulare, and saprophytic mycobacteria were distinguished by digestion with Nar 1 restriction endonuclease. These results suggest that PCR amplification followed by restriction enzyme digestion of the PCR product is a rapid, specific, and highly sensitive technique for the detection and speciation of mycobacteria in paraffin-embedded tissues.

Base Sequence↗
PubMed1990

Fruit allergy: demonstration of IgE antibodies to a 30 kd protein present in several fruits.

A patient who had experienced allergic responses to various fruits developed an acute anaphylactic reaction after the ingestion of a local strain of cling peaches. The patient's serum, but not control sera, contained IgE antibodies reactive to extracts from peaches, guavas, bananas, mandarins, and strawberries in an ELISA. The patient's serum, however, did not demonstrate elevated levels of IgE antibodies to extracts from apples, pears, and nectarines. Adsorption of the patient's serum with extracts from peaches, strawberries, and mandarins resulted in a decline of detectable IgE antibodies to these fruits. Adsorption with extracts from apples and pears had no such effect. These results demonstrate the specificity of the patient's IgE antibodies to selected fruits only. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western blotting revealed a 30 kda of protein that was recognized by the IgE antibodies in the patient's serum. This protein was not present in extracts from pears or apples. Our results highlight the importance of specific allergens in considering acute allergic reactions to individuals exhibiting sensitivity to various foods or fruits.

Adult↗
PubMed1989

A 180-kilodalton protein from Mycobacterium tuberculosis defined by a human T cell clone.

A high molecular weight protein from Mycobacterium tuberculosis (M. tuberculosis) has been identified, that is recognized by peripheral blood mononuclear cells from several tuberculous patients and by a T cell clone derived from a patient with tuberculous pleurisy. Purification of this fraction demonstrated biological activity to reside in a 180-kDa protein component. This mycobacterial protein appears to exist in some, but not all mycobacteria as the clone reacts to M. tuberculosis, BCG M. kansasii, M. flavescens and M. fortuitum, but not to M. intracellulare, M. scrofulaceum or a variety of gram-positive or gram-negative bacteria, or to PPD. Specific anti-genic challenge of the T cell clone in the presence of irradiated antigen presenting cells results in proliferation and interleukin-2 (IL-2) production. Proliferation is restricted to HLA Class II antigens as antigenic recognition occurs only in the presence of either one of the two parental DR haplotypes. Peripheral blood mononuclear cells from several other patients with pulmonary tuberculosis also proliferate in response to this antigen, emphasizing the relevance of T cell cloning techniques in identifying important mycobacterial antigens.

Antigen-Presenting Cells↗
PubMed1989

Arthralgias as a presenting manifestation of primary biliary cirrhosis.

Two patients presenting with arthralgias had associated minor elevations in liver enzymes. Each patient's serum had a cytoplasmic pattern of fluorescence on HEp-2 cells which led to the detection of antimitochondrial antibodies. Liver biopsy in both patients revealed primary biliary cirrhosis. Awareness of this limited, articular presentation of primary biliary cirrhosis may result in early treatment and the potential to arrest liver damage in some patients.

Adult↗
PubMed1987

Depressed 3H-thymidine incorporation by measles infected mononuclear cells can be corrected by treatment with isoprinosine or 5-fluoro-2-deoxyuridine.

Incorporation of thymidine by measles infected PHA-activated lymphocytes was found to be depressed although production of interleukin 2 (IL-2) and expression of IL-2 receptors on these cells was similar to that of non-infected cells. The decrease in incorporation of 3H-thymidine by infected cells was not due to cell death and could be restored by treating the cells with isoprinosine or 5-fluoro-2-deoxyuridine. These results suggest that the depressed incorporation of 3H-thymidine by measles-infected cells is not due to inhibition of early events required for lymphocyte proliferation, but is rather due to interference in the thymidine pathway required for the synthesis of DNA.

Antigens, Surface↗
PubMed1986

Tumor cells stimulate interleukin 1 (IL-1) production from enriched large granular lymphocytes.

When enriched large granular lymphocytes (LGLs) were activated by K562 cells substantial amounts of interleukin 1 (IL-1) could be detected in the supernatants as measured by the mouse thymocyte assay. IL-1 could also be produced by LGLs treated with other tumor cells according to their ability to be lysed by LGLs. Therefore PLC/PRF/5 hepatoma cells which were moderately sensitive to LGL attack stimulated moderate amounts of IL-1 from the LGLs. Yac-1 cells and human fibroblasts which are resistant to LGL cytolysis did not activate LGLs to produce significant amounts of IL-1. IL-1 was shown to be produced by LGLs and not by the stimulatory tumor cells. Interferon-alpha (IFN), which reduced the susceptibility of target cells to be lysed by LGLs, also inhibited their ability to stimulate IL-1 production from LGLs. The IL-1 stimulatory effect of tumor cells on LGLs could not be attributed to Mycoplasma or endotoxin contamination. It is suggested that LGLs release IL-1 when they encounter susceptible cells and that release of this cytokine is important in the subsequent lysis of target cells.

Animals↗
PubMed1979

Desensitization of patients with bee sting allergy using pure bee venom.

Forty patients who had previously experienced severe systemic reactions after a bee sting were desensitized using pure bee venom. A modified 'Rush' regimen was employed whereby patients received two injections a week and reached maximal desensitization in 5 weeks. Eleven patients have subsequently been stung again and have developed no generalized reaction. Although this form of desensitization is considered to be highly effective in protecting sensitive patients, both generalized and local side-effects were frequent. Maintenance desensitizing injections are required every month for an indefinite period. It is concluded that desensitization with pure been venom should be undertaken only in highly selected sensitive patients, and should be performed under strict control.

Adolescent↗
PubMed1979

Evaluation of leucocyte adherence inhibition in hepatocellular carcinoma.

The value of the leucocyte adherence inhibition (LAI) test in the diagnosis of hepatocellular carcinoma (HCG) was investigated in 36 patients with this tumour. The sensitivity and specificity of the tube LAI test was assessed in 21 patients with HCC, 15 apparently healthy individuals, 9 patients with various forms of benign liver disease and 5 patients with non-hepatic neoplasms. In only 42% of the HCC patients tested was leucocyte adherence to glass reduced to a greater extent than in the healthy controls and in the patients with non-hepatic neoplasms, and the differences were not statistically significant. Moreover, positive results were obtained in 6/9 patients with benign hepatic disease. A further 15 patients were tested against extracts of HCC tissue using the haemacytometer LAI method. Of these, 53% gave positive results. In all, only 17/36 patients (47%) gave positive LAI responses. The test is thus of limited value in the diagnosis of HCC. The high false-negative result rate may be due either to abrogation of the immune response in HCC patients with large tumour burdens or to antigenic heterogeneity in HCC.

Adult↗
PubMed1979

Further evidence for independent segregation of the HLA system and a structural gene for the sixth component of complement (C6).

Previous studies have shown conflicting results with respect to the relationship between C6 deficiency and the HLA system. The present investigation of two kinships, in which C6 deficiency was associated with the expression of an amorphic (or silent) C6 allele, has provided further evidence for the genetic independence of a structural C6 locus and the HLA system.

Adult↗
PubMed1978

The effect of levamisole on E-rosette formation by trypsinized lymphocytes.

Normal lymphocytes treated with trypsin lost their ability to form normal numbers of rosettes with sheep red blood cells. The recovery in E-rosette forming capacity of trypsinized cells was considerably augmented when the cells were incubated in the presence of a wide range of concentrations of the immunostimulatory drug, levamisole. Substantial recovery of rosette-forming ability was seen 2 hr after incubation of trypsinized cells with levamisole.

Humans↗
PubMed1978

Inhibitory effect of prostaglandin A1 on neutrophil motility.

Using Boyden chambers, Prostaglandin A1 (PGA1) was shown to inhibit directed movement of polymorphonuclear (PMN) leucocytes to the chemoattractants endotoxin-activated serum and casein, and in random migration systems. Depressed chemotaxis could not be entirely attributed to defective random migration, as the drug was shown to inhibit both chemokinesis (stimulated random migration) and "true chemotaxis". In addition, PGA1 inhibited the movement of neutrophils out of capillary tubes and substantially reduced hexose monophosphate shunt (HMPS) activity. Mice injected with PGA1 demonstrated significantly less PMN movement into trypticase-soy-broth-induced peritoneal exudates, and it is postulated that during inflammatory processes release of PGA1 increases cell accumulation at the site, thereby amplifying the inflammatory response.

Chemotaxis, Leukocyte↗
PubMed1978

The effect of chemotactic factors and agents which influence neutrophil movement on anaerobic glycolysis and hexose monophosphate shunt activity.

The effects of two chemotactic factors, endotoxin activated serm (EAS) and casein and a number of drugs known to affect intracellular cyclic nucleotide levels and various froms of neutrophil movement, on neutrophil anaerobic glycolysis and hexose monophosphate shunt (HMPS) activity were assessed. EAS caused stimulation of glycolysis. HMPS activity and NBT reduction, but casein was without effect on glycolysis and NBT reduction and inhibited HMPS activity. Drug known to increase intracellular cAMP levels caused a depression of HMPS activity whereas those reported to elevate cGMP had a variety of effects. Glycolysis was not affected by any of these agents. These results indicate a lack of relationship between cyclic nucleotide effect on cell motility and neutrophil glycolysis and HMPS activity.

Caseins↗
PubMed1978

Defective neutrophil motility and recurrent infection. In vitro and in vivo effects of levamisole.

Eighteen patients with primary abnormalities of neutrophil chemotaxis are described. The most common clinical presentation was one of recurrent upper respiratory tract infection (nine patients) or recurrent pyoderma (seven patients), and two children had a history of oropharyngeal candidiasis and recurrent skin sepsis. Of these eighteen patients, sixteen had intrinsic polymorphonuclear leucocyte (PMN) defects as shown by diminished random migration and movement towards endotoxin-activated serum. PMN chemotaxis towards casein was, however, normal. In nine out of the latter patients, there was an associated inability of the serum to generate chemotactic factors. PMN from two adult patients, both suffering from recurrent boils, moved normally both in random and directed systems, but sera from these patients contained heat-stable inhibitors of neutrophil chemotaxis. In vitro levamisole treatment (10(-3) M) markedly improved the PMN function. When patients were treated with levamisole, however, no clinical response was noted, although PMN movement improved in a number of cases.

Adolescent↗