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Biomedical subjects

J Bayer

Publications and source records attributed to J Bayer.

35 records · Page 2Linked to original sources
PubMed1993

[Herpes simplex keratitis. On the long-term prognosis of first transplants after penetrating keratoplasty].

Eighty-six consecutive first grafts performed between 1980 and 1990 (86 patients) for herpes simplex keratitis (HSK) were studied retrospectively (mean follow-up 4.1 years). Indications for penetrating keratoplasty (PKP) included: persistent inflammation, descemetocele or perforation (21/86); stromal opacities with vascularization (43/86), and avascular stromal opacities (22/86). The overall survival rate of clear transplants was 80% after 2 and 68% after 11 years. Corneal inflammation at the time of surgery was found to be a prognostic factor, but not corneal vascularization: The 2-year survival rates for clear grafts were 95% for avascular and 83% for vascularized stromal opacities in clinically inactive eyes, as against 58% for clinically active corneas at the time of surgery. HSV-specific structural proteins were immunohistochemically detectable most often in keratectomy specimens from patients with corneal inflammation before the operation (91%). In the group of clinically inactive stromal opacities, HSV antigens were detectable significantly (P < 0.001, chi-square test) more often in keratectomy specimens from patients with avascular opacities than in those with vascularized opacities. This may explain why corneal vascularization is not a significant risk factor for HSV recurrences. The different frequency of HSV-specific proteins in avascular and vascularized corneas merits attention in the intra- and postoperative management of patients with HSK undergoing corneal transplantation.

Adolescent↗
PubMed1993

Progress in childhood cancer care in Florida. 1970-1992.

Pediatric cancer has been a priority in Florida since 1970. That year physicians established a statewide network of children's tumor programs, the Florida Association of Pediatric Tumor Programs (FAPTP), which has grown from the initial two programs to 10 in 1992 and now maintains a registry with follow-up to monitor incidence and other indicators. State-of-the-art care is provided through affiliation with the Pediatric Oncology Group. The incidence of pediatric cancer in Florida is equivalent to national rates, but the number of children followed in 1991 had grown to approximately 2,000. The number receiving care has increased an average of 13% annually since 1981. Services for these patients should be reviewed on a continuing basis to assure access to specialized programs.

Adolescent↗
PubMed1992

The incidence of pediatric cancer in Florida, 1981 to 1986.

Incidence rates for pediatric (ages, 0 to 14 years) cancer in the state of Florida were produced for the period 1981 to 1986 and compared with national data to investigate variations in pediatric cancer incidence. Overall, Florida had an incidence rate of 12.77 per 100,000; this was not significantly higher than expected based on national rates (standardized incidence ratio, 1.0; 95% confidence interval, 0.9 to 1.0). Compared with national rates, whites residing in Florida had an increased rate of acute lymphocytic leukemia and decreased rate for soft tissue sarcomas (other than rhabdomyosarcoma), "other leukemias," and "other" cancers. Nonwhites residing in Florida had increased rates for soft tissue sarcomas (other than rhabdomyosarcoma) and decreased rates of "other" cancers. Boys in Florida had increased rates for retinoblastoma and acute lymphocytic leukemia and decreased rates for "other leukemias" and "other" cancers. Rates for girls were decreased for neuroblastoma and "other leukemias."

Adolescent↗
PubMed1991

Culture of hematopoietic stem cells purified from murine bone marrow.

The results of the Y-chromosome in situ hybridization experiments, the MRA assessment, and the long-term production of CFU-GM in vitro indicate that our protocol to sort low density WGA+, 15/1.1-, Rh123 dull cells enriches about 200-fold for PHSC. Assays for spleen colony formation (CFU-S) and radioprotection (30-day survival) were shown to be unspecific for PHSC, and, therefore, we lack a quantitative PHSC assay. The absolute number of PHSC in the bone marrow is not known any more, the purity of our sorted population likewise is unknown. Long-term repopulating cells (PHSC) could be separated from short-term repopulating ones by using Rh123 staining. The short-term repopulating cells (Rh123 bright) provided sufficient offspring to protect lethally irradiated mice until endogenous PHSC could reconstitute hematopoiesis. These cells are therefore of interest for bone marrow transplantation, because they provide radioprotection without long-term repopulation and graft-versus-host disease. For gene therapy these cells are of limited use, and PHSC with extensive replication are needed. The PHSC were not cultured successfully. Less than 15% of the sorted Rh123 dull cells responded in semisolid or liquid cultures in the presence of growth factors. Proliferation without differentiation was not observed. This may indicate that the right growth factor has not been found yet. On the other hand, about 30% of the cells responded in stromal layers of long-term bone marrow cultures and prolonged CFU-GM production and cobblestone area formation were observed there, suggesting that cell-cell contact and adherence molecules play a regulatory role in PHSC replication.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Detection of Y chromosome by in situ hybridization in combination with membrane antigens by two-color immunofluorescence.

Discrimination between donor and recipient peripheral blood cells through detection of the Y chromosome can be useful to document chimerism and engraftment after sex-mismatched bone marrow transplantation. Currently applied methods are hampered by the selection of cells (e.g., karyotyping of cells in metaphase) or by the fact that the detection of Y chromosome by in situ hybridization with specific probes does not allow further characterization of the cells. Although quinacrine staining of Y chromosomes can be performed on cells previously marked for membrane antigens, this staining is not fully discriminative between male and female cells. To circumvent this, a technique has been developed, in which mononuclear cells in suspension were stained for membrane antigens by the consecutive use of monoclonal antibodies and tetramethylrhodamine isothiocyanate conjugates. After the cells were spun down on slides and fixed with methanol/acetic acid and formaldehyde, in situ hybridization with a biotinylated Y-chromosome-specific DNA probe was performed. The probe was detected with avidin-fluorescein isothiocyanate and the signal was amplified by consecutive incubation with biotinylated anti-avidin and avidin-fluorescein isothiocyanate. The membrane staining for various antigens remained undisturbed during the hybridization procedure and the Y probe discriminated almost completely between male and female cells. Therefore, this approach allowed us to determine the chimerism within different subpopulations of unseparated mononuclear cells after sex-mismatched bone marrow transplantation with a sensitivity of 98% and a specificity of 100%.

Antibodies, Monoclonal↗
PubMed1988

Pathomechanism of brain oedema in experimental intracerebral mass haemorrhage.

The prognosis of intracerebral haemorrhage is extremely poor when arterial hypertension is present. We investigated elastance of the brain tissue and brain hydraulic conductivity in normotensive (MAP approximately 110 mmHg) and hypertensive (MAP approximately 170 mmHg/angiotensin infusion) cats following a stereotactically produced intracerebral haemorrhage. For 12 hours after the onset of haemorrhage we registered the course of ICP, subsequently the water content of cortex, white matter and basal ganglia as well as the interstitial concentration of serum proteins in the corresponding regions were determined (Evans-Blue, immunofluorescence). Hypertension was associated with a slight increase in ICP and tissue water content but with a 3 fold more elevated content of interstitial serum proteins. Immunofluorescence analysis showed the oedema in the hypertensive group to be vasogenic in nature and in the normotensive cats to originate from the haematoma itself. The generally poor outcome of intracerebral mass haemorrhage in hypertensive subjects could be ascribed to the nature of the concomitant brain oedema, as described in this study.

Animals↗
PubMed1988

Morphosyntactic processing in German agrammatism: a replication and revision of von Stockert/Bader (1976).

This paper reports the results of a revised replication of the von Stockert/Bader constituent ordering study (1976) with German agrammatics. Part 1 describes why such a replication was necessary. In part 2, the original study is summarized and the weaknesses are identified which caused a revision. Part 3 reports the replication study with 10 German agrammatics. The findings of the original study with respect to Broca's aphasics could not be replicated: instead of an almost total loss of morphosyntactic sensitivity, there was almost total preservation. Part 4 eliminates the possibility of a population artefact by reporting on the performance of 3 patients with global aphasia. Part 5 integrates the results of this study within a larger framework of syntax and inflectional morphology in (German) agrammatism.

Aphasia↗
PubMed1987

Sensitization of nociceptive cutaneous nerve fibers from the rat's tail by noxious mechanical stimulation.

This single fiber study on rat tail nerve afferents attempts to establish a peripheral neural correlate for the hyperalgesia to mechanical stimulation which follows injury to the skin. Mechano-heat sensitive C fibers (MH-C or "polymodal" nociceptors) and high-threshold mechanoreceptive A delta fibers (HTM-A delta) were examined with a series of constant noxious pressure stimulations (4-6-8-4 N on 25 mm2, 120 s each, 5 min intervals). These injurious stimuli were either directed to the most sensitive spot of the receptive fields (central stimulation) or closely outside their borders (1-5 mm). With this protocol no clear sensitization was seen in MH-C fibers apart from a stronger dynamic response to central stimulation in some of them. In contrast, most HTM-A delta units, irrespective of the site of noxious stimulation, developed spontaneous activity, lowering of their von Frey thresholds and expansion of their receptive fields. All HTM-A delta units responded to outside stimulation: upon the first stimulus (4 N) there was a delayed discharge of continuously increasing frequency ("recruited response"), but the onset of the last stimulation (4 N repeated) evoked vigorous dynamic responses in many fibers. The recruitment of HTM-A delta nociceptor activity may contribute to post-injury hyperalgesia to mechanical stimulation and it may counteract adaptation of the single afferent fiber during prolonged noxious influence.

Animals↗