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Biomedical subjects

C Schmidt

Publications and source records attributed to C Schmidt.

At least 361 records · Page 20Linked to original sources
PubMed1992

[A measuring device for calculating electrical impedance of the heart in clinical conditions].

Changes in the electrical impedance of tissue can indicate structural changes. This suggests a technique for the noninvasive detection of allograft rejection after heart transplantation. The direct electrical connection to the heart and the application of a measuring current to the myocardium requires a high standard of safety. A device was developed for measuring cardiac impedance using a sinusoidal current of 20 microA at a frequency of 15 kHz. The control logic ensures a slow current onset and also an immediate cessation in case of conductor fracture or excessive voltage. Initial results in patients with normal recovery after heart transplantation revealed a rapid drop in impedance to about 70% of the initial value in the 1st 48 hours and then a stable course. In the sole rejection episode observed so far, the impedance increased again to 85% of the initial value. This paper discusses the technical safety requirements and the design of the device, and presents initial results of clinical examinations.

Cardiography, Impedance↗
PubMed1992

Stability of pO2, pCO2 and pH in heparinized whole blood samples: influence of storage temperature with regard to leukocyte count and syringe material.

Influences of storage temperature and blood cell metabolism in different types of syringes were investigated. Experiments were performed on blood samples with normal and elevated leukocyte counts. After equilibration with gas mixtures at normal pO2 (86 mm Hg/11.5 kPa) and elevated pO2 (140 mm Hg/18.7 kPa), sequential blood gas analyses were done within one hour. Storage temperatures were 4 degrees C or 22 degrees C. In the first group of experiments we compared glass samplers with plastic syringes at different storage temperatures with regard to deviations of blood gas concentrations. The analysed samples had a normal cell count. Blood stored in glass syringes in ice water served as the reference, and it displayed virtually no changes. The deviations of pCO2 and pH were relatively small. In plastic syringes the greatest increases for pO2 occurred after storage at 4 degrees C, which can be explained by the increased solubility of oxygen and the higher O2 affinity of haemoglobin at 4 degrees C. When stored at room temperature, the deviations in plastic syringes were smaller. In a second group of experiments, the influence of cell metabolism was studied. Blood gases were analysed in samples with elevated leukocyte counts (20 x 10(9)/l, 40 x 10(9)/l, 60 x 10(9)/l), and only glass syringes were used. It was demonstrated that after storage at 22 degrees C considerable losses in pO2 occurred, while at 4 degrees C there was virtually no change. Deviations of pO2, pCO2 and pH are described in detail.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Cells↗
PubMed1992

Invasive cervical cancer following cryotherapy for cervical intraepithelial neoplasia or human papillomavirus infection.

OBJECTIVE: To determine the following: 1) the causes for the failure of cervical cryotherapy to prevent cervical cancer, and 2) whether cervical cryotherapy is associated with the development of cervical adenocarcinoma rather than squamous carcinoma. METHODS: We reviewed the medical charts of 327 women with cervical cancer. One hundred forty-seven for whom pertinent history was missing were contacted by telephone or at clinic visits. History obtained verbally was confirmed by outside medical records. Cervical biopsies (N = 16) and endocervical curettages (ECCs) (N = 15) performed before cryotherapy and biopsies at the diagnosis of cancer (N = 21) were reviewed. RESULTS: Twenty-one women with cervical cancer had a history of cryotherapy for cervical intraepithelial neoplasia (CIN) or human papillomavirus infection (HPV). The interval between cryotherapy and cancer was more than 2 years in 19 and more than 5 years in ten. Several categories of pre-treatment errors were identified. Evaluation before cryotherapy was appropriate in only nine cases. Interpretive errors were noted in three of 16 cervical biopsies and ten of 15 ECCs. After cryotherapy, 12% of women had appropriate follow-up. Of the invasive cancers that developed, 24% in the cryotherapy group and 21% in the non-cryotherapy group were adenocarcinomas. CONCLUSIONS: Careful evaluation before cryotherapy, accurate pathology reports, and consistent long-term follow-up are necessary if cryotherapy is to be used to treat CIN or HPV. We found no evidence that cryotherapy is associated with the development of cervical adenocarcinoma.

Adenocarcinoma↗
PubMed1991

The structure of the gene coding for the mouse cell adhesion molecule uvomorulin.

We have recently shown that the Ca2+ dependent cell adhesion molecule uvomorulin is encoded by a single gene, localized on mouse chromosome 8. Here we describe the organization of the uvomorulin gene and give an initial characterization of the uvomorulin promoter. Uvomorulin is encoded by 16 exons, which are distributed over a region of more than 40 kb genomic DNA. The exon structure of the genes for uvomorulin and its chicken homologue L-CAM are nearly identical and thus highly conserved. The relationship between the exon structure and the structure of the uvomorulin protein is analysed. The initiation site of transcription of the uvomorulin gene is located 127 bp upstream of the translation start site in a GC-rich region with no TATA-box, but with a GC-box in position -48 and a CCAAT-box starting at position -65 with respect to the transcription start site. 1.6 kb of the uvomorulin promoter (-1492 to + 92) confer cell type specific promoter activity to the CAT reporter gene. Homologies to known cis acting elements of other promoters are discussed.

3T3 Cells↗
PubMed1991

Nonresponsiveness to an immunodominant Epstein-Barr virus-encoded cytotoxic T-lymphocyte epitope in nuclear antigen 3A: implications for vaccine strategies.

An immunodominant Epstein-Barr virus (EBV)-encoded cytotoxic T lymphocyte (CTL) epitope has been mapped to the EBV nuclear antigen 3A. The epitope, represented by the peptide sequence AWNAGFLRGRAYGLD (hereafter termed AWNA), is restricted through the HLA-B8 allele and is expressed by type A but not type B-infected transformants. Herein, we show that EBV-specific memory CTLs from an HLA-B8+ healthy virus carrier, JS, did not respond in vitro to AWNA, even though that individual's endogenously infected transformants processed and presented the natural equivalent of this peptide to AWNA-specific CTLs from another B8+ individual. Instead, an epitope, represented by the peptide sequence QLSDTPLIPLTIFVGENTGV, was the dominant EBV-specific CTL epitope in donor JS. This epitope mapped to EBV nuclear antigen 2A, was restricted by an HLA-A2 subtype, and specifically associated with type A strains of EBV. No AWNA-specific CTL precursors were detected by limiting dilution analysis of peripheral blood mononuclear cells from donor JS whereas the precursor frequency of AWNA-specific CTLs from a responder donor, LC, was estimated at 1:4500. The presentation in vivo of an immunogenic epitope-HLA antigen complex is clearly insufficient to guarantee an effective memory CTL response to that foreign epitope. Thus, vaccination strategies based on peptides inducing CTL responses may need to take into account not only the polymorphism of HLA antigens but also possible allelic variation in the repertoires of T-cell receptors.

Amino Acid Sequence↗
PubMed1991

Anti-sedative and anti-cataleptic properties of NCS-382, a gamma-hydroxybutyrate receptor antagonist.

NCS-382 possesses antagonistic properties at gamma-hydroxybutyrate receptor sites. Its effect on the sedative/cataleptic behaviour observed in rats after gamma-hydroxybutyrate administration was investigated. NCS-382 diminished, in a dose-dependent manner, the sedative and/or cataleptic effects of gamma-hydroxybutyrate, as revealed by a variety of sensorimotor tests. These results indicate that the well-known sedative/anaesthetic effects induced by gamma-hydroxybutyrate administration are provoked via stimulation of a specific class(es) of gamma-hydroxybutyrate receptors which exist in the rat brain and which could mediate a local stimulation of opiate synthesis and release.

Animals↗
PubMed1991

[Chronic hemorrhagic pleural effusion in mediastinal pancreatic pseudocyst].

A 48-year-old patient is presented with chronic hemorrhagic pleural effusion due to a pancreatitis-induced pseudocyst. High levels of pleural fluid amylase and demonstration of the pseudocyst by endoscopic retrograde cholangio-pancreatography (ERCP) provided the diagnosis. After chest tube draining for about two weeks curative surgery was undertaken.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1991

Analgesic responses elicited by endogenous enkephalins (protected by mixed peptidase inhibitors) in a variety of morphine-sensitive noxious tests.

It has been suggested that the endogenous opioid peptides, methionine and leucine enkephalin, participate only in naloxone-facilitated antinociceptive responses. To reassess this proposal, analgesic effects resulting from complete inhibition of enkephalin metabolism by intracerebroventricular (i.c.v.) administration of the mixed inhibitor RB 38A (R,S)HONHCOCH2CH(CH2 phi)CONHCH(CH2 phi)COOH) were compared to the effects of morphine (i.c.v.) in various assays commonly used to select analgesics: mouse hot plate-test, tail flick test with mice and rats, electrical stimulation of the tail (TES), paw pressure test with rats, and phenylbenzoquinone-induced writhing test with mice. The ED50s of morphine vs. ED50s of RB 38A in the writhing, hot plate (jumping) and tail flick tests with mice were 0.24 nmol vs. 38 nmol, 1 nmol vs. 36 nmol and 3.2 nmol vs. 285 nmol, respectively. RB 38A (ED30 153 nmol) was only 15 times less active in the tail flick test with rats than morphine and only halve as active in the paw pressure test. Noxious TES in rat was very sensitive to the inhibitory action of endogenous opioids protected by RB 38A, particularly the post-vocalization response which was also shown to be alleviated by antidepressants. All the analgesic effects observed were reversed by naloxone. This first direct evidence of analgesia resulting from peptidase inhibition, in the tail flick test with mice and rats, hot plate (paw lick) and TES shows that the pain suppressive effects of endogenous opioid peptides are not restricted to naloxone-facilitated noxious stimuli but occur more generally, in all morphine-sensitive tests. The differential effects of RB 38A in the various assays is likely to be related to the amount of enkephalins released and to the efficiency of peptidase inactivation in particular brain regions implicated in the control of a given nociceptive input. This mechanism could account for the reduction in side-effects compared to those of morphine following chronic administration of RB 38A.

Analgesics↗
PubMed1991

National Study of Internal Medicine Manpower. XVIII: Subspecialty fellowships with a special look at hematology and oncology, 1988-1989.

OBJECTIVE: To determine the number and distribution of internists in subspecialty training and compare with data collected since 1976; to determine the distribution of activity of subspecialty fellows; and to focus on hematology and oncology. DESIGN: Repeated mail survey with telephone follow-up. PARTICIPANTS: All directors of subspecialty training programs in internal medicine in the United States. RESULTS: The 1988-1989 census identified 7530 fellows in training, 55 more than in 1987-1988. There are 24 more first-year fellows. Reports on the activities of subspecialty fellows show that, overall, 53% of fellows' time is spent in direct patient care, 20% on basic research, 15% on patient-related research, and 12% in teaching. CONCLUSIONS: The number of internists entering subspecialty training has risen at a considerably slower rate in the last 5 years compared with the 5 years before that. The length of subspecialty training has increased significantly since 1976. There has been a shift in subspecialty choice from hematology to oncology and toward joint programs offering both subspecialties.

Education, Medical↗
PubMed1991

Composite response of naive T cells to stimulation with the autologous lymphoblastoid cell line is mediated by CD4 cytotoxic T cell clones and includes an Epstein-Barr virus-specific component.

We have approached the challenge of generating a primary T cell response to Epstein-Barr virus (EBV) in vitro by stimulating naive T cells with the autologous EBV-transformed lymphoblastoid cell line (LCL), a rich source of EBV-associated cytotoxic T lymphocyte (CTL) epitopes. Responsive T cells from three EBV-seronegative donors were cloned in agarose, phenotyped for T cell markers by flow cytometry, and their cytotoxic properties analyzed in the 51Cr release assay. Most clones (greater than 95%) expressed the CD4 phenotype and 59% of these clones showed cytotoxic properties. The dominant CTL response was specific for FCS-associated epitopes presented by FCS-grown autologous LCL target cells and was restricted by class II HLA antigens. Other clonal components included: (i) an EBV-specific response by HLA-restricted CD4 CTL clones that did not discriminate between A- and B-type EBV transformants; (ii) an EBV-specific response by an HLA-restricted CD4 CTL clone that discriminated between A- and B-type transformants, and (iii) a nonspecific cytotoxic response by CD3+,4+,8-, CD3+,4-,8-, and CD3-,4-,8- clones that were broadly allotypic or restricted to the lysis of K562 target cells. The EBV-specific CTL clones did not lyse the autologous EBV-negative B or T cell blasts and their specificity patterns of lysis were supported by the cold target competition data. These studies highlight the role of CD4 CTL in the establishment in vitro of a primary immune response to a human virus.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

Cytotoxic T lymphocyte discrimination between type A Epstein-Barr virus transformants is mapped to an immunodominant epitope in EBNA 3.

An immunodominant Epstein-Barr virus (EBV)-specific cytotoxic T lymphocyte (CTL) epitope, represented by peptide 68, has been mapped to the EBV nuclear antigen, EBNA 3. The epitope is recognized by class I-restricted CTLs through HLA-B8 and is functionally active on type A but not type B lymphoblastoid cell lines (LCLs). Herein we show that peptide 68 is not expressed as a functional CTL epitope by type A LCLs infected with an EBV B95-8 isolate. CTLs from cultures stimulated with autologous type A IARC-BL74 or QIMR-WIL LCLs lysed autologous cells stimulated with phytohaemagglutinin (PHA blasts) and coated with exogenous peptide 68. No peptide 68-specific CTLs were generated in cultures stimulated with autologous type A B95-8 or type B AG876 LCLs. However, the B95-8 LCL coated with peptide 68 was effective in the induction of a peptide-specific CTL response. A peptide 68-specific CTL clone failed to lyse the B95-8 LCL, type B AG876 LCL and PHA blasts, although such targets were lysed when coated with peptide 68.

Amino Acid Sequence↗
PubMed1991

Oligopeptide induction of a secondary cytotoxic T-cell response to Epstein-Barr virus in vitro.

Three Epstein-Barr virus (EBV) nuclear antigen (EBNA)-encoded oligopeptide epitopes have been mapped, each capable of acting as a recognition determinant for class I-restricted lysis by CD8+ cytotoxic T lymphocytes (CTL). This report shows that each peptide, when presented on an appropriate autologous antigen-presenting cell (APC), also stimulates EBV-specific memory T cells present in peripheral blood mononuclear cell (PBMC) populations to develop in vitro into peptide-specific CTL. These CTL specifically lysed autologous EBV-infected lymphoblastoid cell lines (LCL) and peptide-sensitized uninfected targets. Identical viral oligopeptides could therefore function as recognition determinants for both the induction and commission of class I-restricted specific cytotoxicity. A model system is described in which autologous phytohaemagglutinin (PHA) blasts present exogenous peptide during the stimulation phase. The magnitude of the peptide-specific CTL response was dependent on the concentration of peptide added to the APC and specific lysis was inhibited by anti-class I monoclonal antibody (MoAb) but not anti-class II MoAb. Cultures depleted of CD8+ T cells by cell separation with immunomagnetic beads prior to stimulation invariably failed to generate a peptide-specific CTL response. However, the effect of CD4 depletion on CTL activity was equivocal and indicated that a need for CD4+ T cells as accessory helper cells may depend on the efficiency of the APC to elaborate their own help. This model has advantages in the analysis of events involved in the development of CTL activity in vitro.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

Indicators of women's alcohol problems: what women themselves report.

In-depth interviews with 65 women in treatment contributed to a taxonomy of indicators of women's alcohol problems, with five major categories and numerous subcategories. The largest number of client indicators appeared in the Individual (psychological and behavioral) category. The Physiological category included unique indicators regarding physical appearance. Within the Social category, family/partner relationships were emphasized. The taxonomy can be useful in therapeutic assessments, to develop survey items, in comparative research, or in alcohol program development.

Adult↗
PubMed1991

[Primary accuracy of fit of composite inlays produced according to the indirect method].

The primary accuracy of fit of three composite inlay systems was evaluated comparatively. Control inlays were made of a phantom metal. In the proximal-cervical surfaces the resulting median widths of the open margins showing luting agent were as follows: EOS (74.1 microns) greater than Ful-Fil (59.5 microns) greater than Brilliant (43.13 microns) greater than Phantom metal (18.6 microns). Even though, under clinical conditions, composite inlays are attached by means of adhesives, the primary accuracy of fit achieved should be comparable to that of cast restorations, because the long-term stability of the material used for fasting the inlays cannot be warranted.

Composite Resins↗