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Biomedical subjects

S Schmidt

Publications and source records attributed to S Schmidt.

At least 307 records · Page 17Linked to original sources
PubMed1995

A "balanced" Y;16 translocation associated with Turner-like neonatal lymphedema suggests the location of a potential anti-Turner gene on the Y chromosome.

A male patient with Turner-like hydrops in the newborn period (Bonnevie-Ullrich syndrome) was studied. The karyotype was 46,X,t(Y;16)(q11.2;q24) in 100 cells. Chromosome painting with the heterochromatic Y chromosome-specific long arm repeat DYZ2 disclosed that all the hybridization was on the derivative 16. This was confirmed by chromosome painting with DYZ1, the other major Y long arm heterochromatic repeat, and DYZ3, the Y alphoid, centromeric repeat which showed chromosomal separation of the 2 stained regions. To further localize the breakpoint, FISH was performed using individual YACs from a Y-YAC contig (Foote et al., 1992). This disclosed two YACs (yOX111 and yOX123) which hybridized to both the Y and der16 chromosomes. The YACS spanning the translocation breakpoint region were located just proximal to the Y heterochromatin boundary. The recent discovery of a candidate gene for the azoospermia factor (AZF) in this region (Ma et al., 1993) suggests the possibility that there are several Y-expressed genes adjacent to the heterochromatin boundary (as there are near the pseudoautosomal boundary) which may include a gene involved with lymphedema which is disrupted by the translocation in this patient.

Chromosome Mapping↗
PubMed1995

The role of autoimmune T lymphocytes in the pathogenesis of multiple sclerosis.

Autoimmune T cells play a key role as regulators and effectors of autoimmune disease. In multiple sclerosis (MS), activated T cells specific for myelin components or other locally expressed autoantigens enter the CNS and recognize their antigen(s) on local antigen-presenting cells. After local stimulation, the T cells produce a plethora of cytokines and inflammatory mediators that have profound effects on the local cellular environment, induce and recruit additional inflammatory cells, and contribute to myelin damage. An increasingly detailed knowledge of these processes will greatly facilitate the development of new immunotherapies. This article focuses on the role of T cells in MS. We provide a brief overview of the principles of T-cell immunology, discuss the experimental techniques available for studying T cells, address the role of T cells in the pathogenesis of MS, and highlight modern concepts for immunotherapy.

Amino Acid Sequence↗
PubMed1995

Reexamining the Snodgrass and Corwin 1988 picture identification norms.

Snodgrass and Corwin (1988) provided a database of 150 fragmented pictures identified by subjects only 35% of the time. However, recent research by Koch, Abbey, and Schmidt in 1995 with these pictures has yielded higher identification rates. The present study examined the difference in identification rates between Koch, et al., 1995 and Snodgrass and Corwin in 1988. 85 subjects were given 25 min. to identify all 150 pictures from Snodgrass and Corwin. Of the 150 pictures, 95 were identified more than 35% of the time. Since Snodgrass and Corwin used an implicit-learning task while the present study used an object-identification task, the present findings suggest that identification rates may be specific to the type of object-recognition task employed.

Adult↗
PubMed1995

Association of M235T variant of the angiotensinogen gene with familial hypertension of early onset.

A higher frequency of a variant of the angiotensinogen gene characterized by a transition in exon 2 causing a replacement of methionine by threonine (M235T) has recently been found in hypertensive individuals, but not all authors were able to confirm this observation. We examined (i) 219 patients with primary hypertension, (ii) 92 normotensive controls (spouses), and (iii) a sample of the general population (blood donors, n = 139). Analysis of genomic DNA was performed by PCR amplification and alleles were separated on agarose gels. In the general population and in normotensive spouses the respective frequencies of the T and M alleles were: general population: M = 0.6, T = 0.4; normotensive spouses: M = 0.59, T = 0.41. A significantly higher frequency of the 235T allele was found in hypertensive individuals with a family history of hypertension and an onset of hypertension before 50 years of age (spouses: 0.41 versus HT with age of onset < or = 50 years and family history of HT: 0.56; P = 0.01 by chi 2). In conclusion, the present study confirms the observation of a higher frequency of the 235T allele of the angiotensinogen gene in hypertension and identifies individuals with family history and early onset of hypertension as individuals at risk.

Adolescent↗
PubMed1995

[Effect of chronic alcohol abuse on the phagocytotic activity of blood monocytes].

The phagocytic abilities of human monocytes/macrophages have been investigated in people with chronic alcohol abuse. The blood monocytes of the patients were tested in three functional systems: Fc-receptor-mediated phagocytosis, phagocytosis via complement receptor interaction and the so-called lectinophagocytosis. In a group of 57 alcoholics, the values for the phagocytic ability were distributed over a wide range by using all three tests in comparison with a group of 23 non-drinking control persons. However, a significant change in the monocytic function by ethanol could not be observed. Also a correlation between age, liver damage or abstinent periods with respect for these forms of phagocytosis could not be evaluated. As a result of our investigations we discuss our hypothesis, that in chronic alcoholics the so-called "unspecific defense mechanisms" are not altered at all: on the contrary, sometimes they have been up-regulated. A functional defect of specific defense mechanisms, however, has been observed by other investigators. Accordingly, we assume a compensatory up-regulation of "unspecific" immune reactions in long-term alcoholics.

Adult↗
PubMed1995

[Does an association between angiotensin I converting enzyme gene polymorphism and the prevalence of diabetic nephropathy in patients with diabetes type II exist?].

In type I diabetic patients association has been found between the insertion/deletion (I/D) polymorphism in the gene of angiotensin converting enzyme and the presence of diabetic nephropathy. The aim of that study was to assess this association in a cohort of type II diabetics. We examined 109 patients of more than 10 years duration of type II diabetes. Nephropathy (defined as at least confirmed albuminuria > 30 mg/24h) was present in 37 subjects. The I/D polymorphism was analyzed with PCR technique. Allele frequencies in the overall diabetic population did not differ significantly from the normal population. Distribution of genotypes was not significantly different between examined patients with and those without nephropathy. We conclude that the distribution of ACE gene polymorphism is similar in diabetic subjects and in general population and there is not association between I/D polymorphism and nephropathy in type II diabetic patients.

Aged↗
PubMed1994

Mutation of conserved domain II alters the sequence specificity of DNA binding by the p53 protein.

We have mutagenized human p53 expressed in yeast and selected two mutants, 121F and 123A, which activate transcription from one, rather than the normal two, copies of the consensus p53 DNA binding sequence. Both mutants have a 6-fold increase in affinity for a single copy of the sequence GGG CATG CCC. The 121F mutant has a decrease, and the 123A mutant an increase, in the affinity for the sequence GAA CATG TTC. This genetic and biochemical evidence supports the crystallographic finding that amino acid 120 contacts guanine in the major groove at the second position in the consensus. The major p53 binding site in the p21WAF1/CIP1 promoter resembles the GAA CATG TTC form of the consensus. Compared with wild type p53, the 121F mutant has a 7-fold lower affinity for the p21WAF1/CIP1 site in vitro, and the 121F mutant is defective in p21 induction in vivo. Mutants with subtly altered sequence specificity may facilitate dissection of downstream pathways activated by p53.

Animals↗
PubMed1994

Temporal auditory summation in the echolocating bat, Tadarida brasiliensis.

Auditory thresholds improve with increasing signal duration within the maximum integration time of the auditory system, a phenomenon called temporal summation. The temporal summation function is a basic characteristic of particular relevance for bat sonar, as it determines the ability to detect targets with short echolocation calls. Temporal summation was studied in 6 Mexican free-tailed bats (Tadarida brasiliensis) in a forced two-choice behavioural test. Masked auditory thresholds for 40-kHz test tone pulses with durations between 2 ms and 400 ms were determined in broadband noise of two different spectrum levels (-18 dB, +17 dB). At both masker levels, thresholds decreased by considerably more than 10 dB per decade of duration. The time constants of the summation functions, which are a measure of the maximum integration time, shortened significantly with increasing masker level from 62 ms to 14 ms. The steep summation functions are only partly accounted for by spectral splatter. This suggests that the bats are capable of a neural overintegration of sound intensity. Finally, it is shown that such short time constants are typical for echolocating animals, and the implications of the found summation functions for echolocation are considered.

Acoustic Stimulation↗
PubMed1994

Evaluation of three new hydrocolloid dressings: retention of dressing integrity and biodegradability of absorbent components attenuate inflammation.

Residues from hydrocolloid dressings (HCDs) that originate from matrix disintegration and nonbiodegradability of the absorbent components, may cause deep-seated, unresolved inflammation in tissue that appears otherwise healed. The purpose of this study was to evaluate three new HCDs that were formulated with the goal of attenuating the inflammatory responses that may arise from HCD therapy. Two of the HCDs (A-106 and A-107) consisted of conventional absorbents dispersed in a new maceration-resistant adhesive matrix. The same matrix, mixed with potentially biodegradable dextran microspheres, formed the third dressing (Dextran Bead Dressing [DBD]). In this pilot scale study these novel dressings were evaluated on full-thickness dermal wounds on swine. Restore (Hollister) and DuoDERM CGF (Convatec) dressings were used as controls. Wound healing was evaluated histomorphometrically. Pertinent histologic parameters were ranked from wound tissue that was harvested 18 days after wounding. Grossly visible dressing disintegration ranged from minimal (DBD) to severe (Restore). Disintegration of other dressings was moderate. The percentage of tissue sections exhibiting giant cells reflected, in parallel, the observed extent of dressing disintegration. Thirty-eight percent of wounds dressed with DBD contained giant cells; 74 and 100% of wounds treated with DuoDERM CGF and Restore, respectively, contained giant cells. DBD-dressed wounds had relatively fewer chronic inflammatory cells than other dressings. These wounds were also characterized by a well-organized collagen matrix and complete reepithelialization. The extent of wound closures was similar for all dressing types except Restore. Closure of Restore-dressed wounds was delayed compared with closure with DBD and DuoDERM CGF on all days of evaluation except one. A-106 and A-107 were comparable to DuoDERM CGF in retention of dressing integrity and the elicited inflammatory tissue response. The DBD dressing appears to possess equivalent properties of typical HCDs while causing minimal tissue reactions.

Absorption↗
PubMed1994

Monoclonal antibodies and idiotypic network activation for ovarian carcinoma.

Antibodies can be processed by the B- and T-cell systems and may lead to a selective activation of the immune system. The network structure of the immune system implicates the possibility of a selective immunization by the activation of idiotypic cascades. In a retrospective analysis, patients with advanced ovarian carcinoma, who had received MAb, against the cancer-associated antigen CA125 for diagnostic purposes, were analyzed for the production of anti-idiotypic antibodies, survival rate, and immunological effects. Furthermore, we started a prospective and randomized study for ovarian cancer patients, using a different antigen, TAG72, for the induction of idiotypic cascades. Our first results on 58 patients with advanced ovarian carcinomas showed that the induction of anti-idiotypic-antibodies against OC125 mimicking the TAA Class III CA125 leads to a prolongation of the survival rate, and, in extended stages, to an induction of antitumoral immunity, and that the induction of idiotypic cascades is also possible for different antigens like TAG72. Summarizing the activation of idiotypic network cascades seems to be a very effective way of intervention in the immune system of patients with advanced stages of ovarian carcinoma. A prospective study of the adjuvant approach seems to be necessary.

Antibodies, Anti-Idiotypic↗
PubMed1994

Genetics of primary hypertension.

New technologies in molecular biology and medicine have opened new avenues for the study of disease. As a result of this, the genetic basis of many diseases has been discovered and candidate genes that contribute to the underlying pathology have been identified. An important approach to test the function of these genes is the establishment of transgenic animal models. Candidate genes can be expressed in these animals to study their regulation in vivo. Furthermore, the pathophysiological consequences of the alteration in gene expression can be investigated in detail. Like many other diseases, primary hypertension is influenced by genetic factors. A number of candidate genes have been implicated in its pathogenesis, and current research efforts are directed toward testing these candidates. For this purpose, several transgenic animal models have been established. Most of this transgenic work has been carried out in mice, but recent efforts have focused on the development of transgenic rat models for hypertension, which may provide the better experimental system for the study of cardiovascular regulation.

Angiotensinogen↗
PubMed1994

[Psychosomatic aspects of focal dystonia: two case reports].

Dystonic movements and other dyskinesias often cause diagnostic difficulties due to their complex symptomatology. Namely focal dystonias are frequently misdiagnosed as conversion reactions. Idiopathic dystonias are generally considered a nonstructural (neurobiochemical) disorder of the basal ganglia. Many case reports, however, have dealt with patients presenting with "atypical" dystonia whose symptoms were relieved by psychotherapy or hypnosis. We present the histories of two young women exhibiting focal dystonia emerging for the first time under circumstances of profound emotional trouble. We discuss the general difficulties in the diagnosis of dystonic movement disorders and review the criteria for the diagnosis of "psychogenic dystonia". The basal ganglia integrate limbic, proprioceptive and sensorimotor inputs to create emotionally and functionally appropriate voluntary movements. Therefore, the traditional dichotomy "psychogenic-somatogenic" appears to be inappropriate when applied to extrapyramidal movement disorders. In a psychosomatic understanding, the assumption of a psychogenic "trigger" for a somatic movement disorder does not mean a contradiction.

Adolescent↗
PubMed1994

[Pharmaceutical and cosmetic emulsifiers].

The present review paper summarizes the most significant theoretical knowledge and factors of correct selection of emulsifiers for cosmetic and pharmaceutical topical emulsions. The problems discussed include securing the stability of emulsions, the origin ant the health and ecological defectlessness of the emulsifier, as well as some others. The comparative study presents also a list of some trade names of traditional and newly designed nonionic emulsifiers produces by important manufacturers used or recommended for this type of emulsions.

Cosmetics↗