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Biomedical subjects

J M Greco

Publications and source records attributed to J M Greco.

36 records · Page 2Linked to original sources
PubMed1984

Processing of MOPC 315 immunoglobulin A oligosaccharides: evidence for endoplasmic reticulum and trans Golgi alpha 1,2-mannosidase activity.

The processing of asparagine-linked oligosaccharides on the alpha-chains of an immunoglobulin A (IgA) has been investigated using MOPC 315 murine plasmacytoma cells. These cells secrete IgA containing complex-type oligosaccharides that were not sensitive to endo-beta-N-acetylglucosaminidase H. In contrast, oligosaccharides present on the intracellular alpha-chain precursor were of the high mannose-type, remaining sensitive to endo-beta-N-acetylglucosaminidase H despite a long intracellular half-life of 2-3 h. The major [3H]mannose-labeled alpha-chain oligosaccharides identified after a 20-min pulse were Man8GlcNAc2 and Man9GlcNAc2. Following chase incubations, the major oligosaccharide accumulating intracellularly was Man6GlcNAc2, which was shown to contain a single alpha 1,2-linked mannose residue. Conversion of Man6GlcNAc2 to complex-type oligosaccharides occurred at the time of secretion since appreciable amounts of Man5GlcNAc2 or further processed structures could not be detected intracellularly. The subcellular locations of the alpha 1,2-mannosidase activities were studied using carbonyl cyanide m-chlorophenylhydrazone and monensin. Despite inhibiting the secretion of IgA, these inhibitors of protein migration did not effect the initial processing of Man9GlcNAc2 to Man6GlcNAc2. Furthermore, no large accumulation of Man5GlcNAc2 occurred, indicating the presence of two subcellular locations of alpha 1,2-mannosidase activity involved in oligosaccharide processing in MOPC 315 cells. Thus, the first three alpha 1,2-linked mannose residues were removed shortly after the alpha-chain was glycosylated, most likely in rough endoplasmic reticulum, since this processing occurred in the presence of carbonyl cyanide m-chlorophenylhydrazone. However, the removal of the final alpha 1,2-linked mannose residue as well as subsequent carbohydrate processing occurred just before IgA secretion, most likely in the trans Golgi complex since processing of Man6GlcNAc2 to Man5GlcNAc2 was greatly inhibited in the presence of monensin.

Acetylglucosaminidase↗
PubMed1978

Alterations of complement system following thermal injury: use in estimation of vital prognosis.

Complement system has been investigated in the first 15 days postburn. Complement titer (measured by a kinetic method of immune hemolysis) decreases immediately after thermal injury. This depression is mainly explained by mechanical leakage and is related to burn surface. No anticomplementary effect has ever been found in this period. After 48 hours complement titer rises. Magnitude and rate of rise are inversely related to the severity of burn trauma (depth and surface). Infection occurrence is statistically related to but somewhat independent of complement levels and interferes with the rate of increase of complement levels. The basis of the rise to normal or elevated complement levels remains unexplained.

Adolescent↗
PubMed1977

The binding of a potent synthetic androgen--methyltrienolone (R 1881)--to cytosol preparations of human prostatic cancer.

The binding of 3H-R 1881 to cytosol prepared from benign and malignant prostatic neoplasms has been investigated. We have demonstrated that high affinity binding of 3H-R 1881 is present in cytosol preparations of benign prostatic hyperplasia, in specimens of prostatic cancer obtained from patients prior to hormonal therapy and in carcinoma of the prostate metastatic to lymph nodes. In addition, high affinity binding was present in all specimens of prostatic cancer from patients who had objective evidence of progressive metastatic disease after an initial response to hormonal therapy. Until greater numbers of patients have been studied the significance of these findings can only be speculative. Because the binding of 3H-R 1881 may measure androgen and progesterone receptors future investigations must include careful steroid specificity studies. Finally, because steroidal hormones exert their major influence within the nucleus of target tissues the measurement of nuclear receptor content may provide a more accurate means to predict the hormonal responsiveness of prostatic cancer.

Animals↗
PubMedDate not supplied

Mental confusion in a patient treated with metronidazole--a concentration-related effect?

We report a case of serious mental confusion, hallucinations, and agitation in a 65 year old man, occurring in close relationship to the intravenous administration of metronidazole. The patient was treated twice, but at different dosages. The confusion and hallucinations occurred at the recommended daily dose of 2.0 g, but did not return at a daily dose of 500 mg. Metronidazole serum concentrations were obtained throughout both courses of therapy; CSF and tissue concentrations were obtained at autopsy. The mental confusion was associated with peak serum concentrations of approximately 40 micrograms/ml. Symptoms resolved within 24-48 hr after stopping metronidazole, and resolution was consistent with a metronidazole half life of 14 hr. We conclude that metronidazole can be associated with a dose- and serum concentration-related mental confusion state, and that this side effect appears completely reversible upon discontinuing the drug.

Aged↗
PubMedDate not supplied

[Long-term alternations in the hypopharyngeal respiratory tract after mandibular setback].

10 patients were evaluated retrospectively for their long-term changes in hypopharyngeal airway space after surgical correction of mandibular prognathism. All patients had undergone mandibular setbacks by way of bilateral sagittal split osteotomies with rigid fixation. The cephalometric evaluation of the hypopharyngeal airway space was based on stable craniofacial landmarks. The results of this study indicate that mandibular setbacks procedures create relative narrowing of the hypopharyngeal airway space, which in isolated cases might contribute to the development of an obstructive sleep apnea syndrome. The clinical implications of these findings are discussed.

Adolescent↗
PubMedDate not supplied

[Maxillary osteotomy: an alternative treatment concept for obstructive sleep apnea syndrome].

This study contributes to the evaluation of the question whether patients with obstructive sleep apnea syndrome might benefit from maxillary surgery. Changes in nasopharyngeal and hypopharyngeal airway spaces of 13 non-apneic patients following maxillary advancement and/or impaction osteotomies were studied retrospectively by cephalometric analysis. The data suggest a long-term increase in both nasopharyngeal airway space and unexpected, in hypopharyngeal airway space which remained stable over time. The clinical implications are discussed in view of previous studies which suggest or recommend orthognathic surgery as a treatment modality in selected patients with obstructive sleep apnea syndrome.

Adolescent↗