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Biomedical subjects

B Alpert

Publications and source records attributed to B Alpert.

At least 73 records · Page 4Linked to original sources
PubMed1983

The microbiologic flora of orofacial abscesses.

Fifty orofacial abscesses were studied using culture techniques for both aerobic and anaerobic organisms. Eighty-six per cent of the specimens contained anaerobes; of this group, 39 per cent had organisms resistant to penicillin.

Abscess↗
PubMed1982

Role of the H-2 complex in induction of T helper cells in vivo. III. Contribution of the I-E subregion to restriction sites recognized by I-A/E-restricted T cells.

Previous studies on negative selection of T cells to sheep erythrocytes in irradiated mice showed that CBA (I-Ak,I-Ek) (kk) T cells comprise two subgroups of cells restricted by I-A (A alpha-A beta) and I-A/E (E alpha-E beta) molecules. Selection of the I-A/E-restricted by I-A (A alpha-A beta) and I-A/E (E alpha-E beta) molecules. Selection of the I-A/E-restricted subset requires that the donor T cells and the selection host share both I-A (E beta) and I-E (E alpha) gene products; only the I-A-restricted cells undergo selection in B10.A(4R) (kb) mice. This paper demonstrates that negative selection of the I-A/E-restricted subgroup of CBA T cells can occur in F1 hybrids between B10.A(4R) and various Ia.7+ (E alpha+) I-E-incompatible strains; selection does not occur in hybrids between B10.A(4R) and Ia.7- (E alpha-) strains. These data suggest that, despite the fact that E alpha chains display detectable structural allelic variations, these chains are functionally nonpolymorphic. This conclusion applies to E alpha k,d,p,r,j chains. With F1 hybrids between B10.A(4R) and another Ia.7+ strain, B10.PL (H-2u), in contrast, only intermediate selection is observed. This finding is consistent with recent evidence that cell surface expression of E alpha-u-E beta dimers displays strong cis preference. In contrast to E alpha+ CBA T cells, E alpha- B10.A(4R) (kb) T cells undergo complete negative selection in hosts matched only in the I-A (and H-2K) subregion, i.e., B10.BR (kk) mice; no selection occurs in B10 (bb) mice. These data imply that Ia-restricted T cells in E alpha- strains are probably restricted solely by I-A molecules.

Animals↗
PubMed1981

Role of the H-2 complex in induction of T helper cells in vivo. II Negative selection of discrete subgroups of T cells restricted by I-A and I-A/E determinants.

Previous studies have shown that negative selection of T cells to sheep erythrocytes (SRC) after adoptive transfer to irradiated mice requires a sharing of H-2 determinants between the donor T cells and the selection hosts. This paper examines which part of the H-2 complex controls selection. The results show that, in the case of T cells of the H-2k haplotype, complete selection occurs with donor host matching limited to the I-A through I-E subregions of the H-2 complex. Selection to SRC was partial in I-A compatible, I-E incompatible hosts, minimal or not detectable in I-A incompatible, I-E compatible hosts, but near-complete in hosts matched at both the I-A and I-E subregions. Consecutive selection in hosts matched solely at (a) the I-A subregion and (b) the I-E subregion led to incomplete selection. From these and other findings it is argued that H-2k T cells comprise a mixture of T cells restricted by I-A and I-A/E hybrid molecules.

Animals↗
PubMed1980

Transient haem-globin interactions in photodeligated carboxyhaemoglobin and subunits.

Although the fixation of ligand to haemoglobin (Hb) is known to be accompanied by changes in protein conformation regulating the oxygen exchange in blood, the mechanism triggering these changes remains undecided. We now report a dynamic approach to this problem using results obtained in a nanosecond laser photolysis study of carboxyhaemoglobin (HbCO) and its isolated subunits. The study is based on our previous observation of a structural evolution of free Hb after photodeligation, manifested through slight variations of the protein spectrum in the microsecond range. It is now found that the isolated subunits also show this behaviour. The duration of the spectral evolution is approximately 2 microseconds for the three proteins and the activation energy of the process approximately 9 kcal mol-1. The spectral evolution is attributed to local conformation changes at the haem region, occurring during the structural relaxation of the freshly deliganded protein. The results for the isolated chains show that such changes exist even in the absence of the R-T transition.

Carboxyhemoglobin↗
PubMed1980

Study of haem structure of photo-deligated haemoglobin by picosecond resonance Raman spectra.

It is well known that the oxygen affinity of haemoglobin depends on the number of combined oxygen molecules. This cooperative effect is considered to arise from a reversible protein transition between two forms which differ in tertiary and quaternary structure. However, the various steps of the structural changes concerning the protein and the haem have not been identified. Using time-resolved spectroscopy coupled to flash photolysis, we have attempted to elucidate the influence of protein on the relaxation processes of haem in haemoglobin. We now report our first results obtained in a picosecond time-resolved resonance Raman study of haemoglobin.

Carboxyhemoglobin↗
PubMed1979

[Heme structure in cooperative and noncooperative hemoglobins: study by resonant Raman diffusion].

The modifications of heme sites of hemoglobin, which should occur upon apoprotein alterations (responsible for variations of oxygen affinity), have been examined by Resonnant Raman scattering. The oxygenated (R) and deoxygenated (T) shape of apoprotein do not modify the heme states. The spectral differences between these forms are essentially due to the presence or the absence of the sixth ligand.

Apoproteins↗
PubMed1979

Morbidity associated with extraoral open reduction of mandibular fractures.

One hundred consecutive extraoral open reductions of mandibular fractures were analyzed in an attempt to quantitate the morbidity of this technique and demonstrate possible predisposing factors. A complication rate of 13% was found in this series. Age of the patient, coexisting systemic disease, operative delay and operative and postoperative misadventures could not be correlated with morbidity. An obvious relationship was found between the area of the fracture and the presence and disposition of teeth in the fracture line, and the incidence of complications. Open reductions of the mandibular angle associated with teeth removed from the fracture line produced the greatest incidence of complications both quantitatively and qualitatively.

Adolescent↗
PubMed1978

Acute frontal sinusitis as a late complication after midfacial trauma.

The anatomical relationships of the frontal and nasoethmoid region are reviewed, with particular emphasis on the nasofrontal drainage system. A case report is presented in which obstruction of the nasofrontal duct created a delayed frontal sinusitis in a patient with severe midfacial trauma. A brief review of the different conditions that can appear as periorbital inflammation in the posttraumatic period is given, followed by a brief discussion of the various therapeutic alternatives available to the surgeon when presented with this situation.

Adult↗