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Biomedical subjects

S Cleveland

Publications and source records attributed to S Cleveland.

At least 19 recordsLinked to original sources
PubMed2001

Correlation between heterogeneous myocardial flow and oxidative metabolism in normoxic and stunned myocardium.

Myocardial blood flow exhibits considerable heterogeneity. Consequently, oxygen supply to the myocardium is also heterogeneous, as is myocardial metabolism. Many lines of evidence show a close correlation between local flow and local metabolism in the normoxic myocardium. So far, myocardial metabolism has predominantly been assessed indirectly by using labeled substrates. We used the (18)O isotope, permitting analytical separation of H2(18)O from the (18)O isotope, as well as quantification of regional oxidative metabolism by measuring the tissue residue of oxidation water in the rabbit myocardium. Correlation of local flow with oxidative metabolism was significant in the normoxic myocardium. This correlation was lost in the postischemic/reperfused myocardium. Apart from the established mechanisms underlying myocardial stunning, a mismatch between local flow and oxidative metabolism might thus also contribute to the postischemic dysfunction. In the normoxic myocardium, function should correlate with metabolism and blood flow. For technical reasons, function has not been assessed on a very local scale. Nevertheless, some considerations are presented on the heterogeneity of function as well as on the scale on which heterogeneity should be investigated to convey physiologically meaningful information on regulatory cardiac mechanisms.

Animals↗
PubMed2000

Spondyloepiphyseal dysplasia congenita associated with conductive hearing loss.

Spondyloepiphyseal dysplasia is a disorder characterized by abnormalities of growth. Previous studies of this disorder have identified a significant incidence of associated hearing loss. Hearing loss has been reported to occur in 25 to 30% of affected patients. To date, all reports of associated hearing loss have indicated the presence of a sensorineural component. In this article, we report the case of a child who was diagnosed with spondyloepiphyseal dysplasia congenita and who was found to have a significant conductive hearing loss with a Carhart's notch, indicating the likely presence of stapes footplate fixation. We also review the diagnosis of this condition and the literature associated with hearing loss as it occurs with this disorder.

Audiometry↗
PubMed1998

Dichromacy characterized by chrominance planes.

Dichromacy is described in terms of dichromatic opponent colour spaces. By means of the perceptual criteria 'equally bright', 'neither blue nor yellow' and 'neither red nor green' and embedding in a three-dimensional colour space, it is possible for each type of dichromat to quantify a null-chrominance plane and a null-luminance plane, both of which intersect in the missing colour. These two null planes (or the trace of their intersection with the chromaticity chart) are the chromaticities of the dichromatic opponent primaries. Since a null-luminance plane contains only colour ('chrominance'), it is simply a chrominance plane. Under the assumption that the retinal short-wavelength cones do not contribute to luminance, the chrominance planes of the three types of dichromats intersect in a common straight line, the 'blue' fundamental primary vector. This constellation may serve as a general characterisation of dichromacy.

Color↗
PubMed1998

Discharge patterns of intramural mechanoreceptive afferents during selective distension of the cat's rectum.

The afferent input from the rectum to the central nervous system (CNS) has yet to be thoroughly characterized. The characteristics of mechanoreceptive rectal afferents have been studied in unanaesthetized decerebrate cats. Following lumbo-sacral laminectomy, single-unit activity (occasionally multi-unit activity) was recorded from centrally cut filaments of the sacral dorsal roots (predominantly S2), while a balloon was inflated in the rectum. Starting from their background activities (mean 15.1 imp sec-1, SD 7.6 imp sec-1), afferent discharge rate increased with increasing balloon pressure (mean threshold 6.3 mmHg, SD 3.6 mmHg). The dependence of firing rate on intrarectal pressure began to flatten out at 25 mmHg (mean; SD 10 mmHg). For 22 out of 29 units (76%) complete saturation occurred at 35 mmHg (mean; SD 15 mmHg) with a maximum discharge rate of 31 imp sec-1 (mean; SD 12.6 imp sec-1). In a number of recording sessions, cyclical rectal contractions were observed. In these cases, changes in firing of the units were closely related to changes in intrarectal pressure. Pressure-related afferent activity could be enhanced by parasympathomimetic drugs which augmented rectal contractions. We conclude that sacral dorsal roots contain afferents from low-threshold mechanoreceptors located in the rectal wall, and that these afferents monitor the filling state and contraction level of the rectum.

Animals↗
PubMed1998

Childhood pseudohypacusis in patients with high risk for actual hearing loss.

OBJECTIVE: While pseudohypacusis or nonorganic hearing loss is a well-recognized phenomenon in adults, it is the aim of this report to heighten the physician's awareness of the occurrence of nonorganic hearing loss in pediatric patients. The medical and otologic histories of 18 cases identified consecutively between 1983 and 1991 at The Children's Hospital, Boston, Massachusetts, were retrospectively reviewed. In these selected cases an analysis of the audiometric configuration, age range, and sex distribution is undertaken. This review highlights the need to rule out pseudohypacusis even in pediatric cases where suspicion is low. A precedent trauma was the presenting complaint in a high percentage of our patient population. This association has not been previously reported in the pediatric literature. While the severity of the traumatic incident was often minor, extensive medical and surgical investigations had been considered before the identification of nonorganic hearing loss. STUDY DESIGN: A retrospective chart analysis of patients identified with pseudohypacusis over a 7-year period. METHODS: A tertiary care children's hospital in an urban community. Eighteen consecutively identified patients examined by a staff audiologists at a tertiary care children's hospital. A specific battery of standard audiologic testing with the goal of detecting pseudohypacusis in children. RESULTS: Successful if additional interventions such as exploratory tympanotomy were avoided. CONCLUSIONS: Pseudohypacusis was identified in 18 patients with a majority having an antecedent history of trauma. Additional interventions were canceled upon the detection of true threshold values. A high index of suspicion of pseudohypacusis in children and an organized standardized battery of audiologic testing will facilitate early identification of these patients and will avert inappropriate interventions.

Adolescent↗
PubMed1995

Magnetic stimulation as a diagnostic tool in cervical nerve root compression and compression-induced neuropathy.

Magnetic stimulation of motor cortex and cervical spinal cord was used to assess motor impairment in patients with either cervical nerve root compression or myelopathy. Evoked potentials were recorded from biceps brachii and abductor pollicis brevis. Our interest centered on whether the paresis resulting from root compression is accompanied by an increased latency of magnetically evoked muscle potentials and whether latency is increased in cases of cervical root compression or myelopathy in which no paresis occurs. Latency increase does appear to be a moderately good indicator of disturbed nerve conduction. In particular, prolonged latencies in cases of "subclinical" paresis could be used as an important diagnostic tool for the early detection of motor deficits in cervical compression radiculopathy and myelopathy.

Electrodiagnosis↗
PubMed1992

The influence of bacterial collagenase on regeneration of severed rat sciatic nerves.

Regeneration of peripheral nerve fibers is impeded by the formation of scar tissue at the site of injury. The possible beneficial effect of collagenase on nerve regeneration was studied using clinical, neurophysiological (evoked potentials) and histological (nerve fiber counts) methods. The sciatic nerves of rats were transected and the severed ends abutted and sewn together. In one series, the area about the lesion was covered with fibrin adhesive and infused with either isotonic saline (controls) or collagenase (treatment group). In the other series, the severed ends of the nerve were inserted into a silicone tube and separated by a collagen plug, which was infused with either saline or collagenase. Compared to the controls, the treated animals showed a significant improvement of clinical and neurophysiological parameters. After 3 months of observation, the collagen content of the transection site was reduced, and in the silicone series, the total number of myelinated axons 5 mm distal to the site of transection was increased, while the fiber diameter distribution was unchanged.

Animals↗
PubMed1992

Association of Crohn's disease and multiple sclerosis. Is there a common background?

Crohn's disease (CD) and multiple sclerosis (MS) share familial occurrence and similar epidemiological traits. Apart from one report of both diseases occurring among consanguineous relatives, only three cases of CD and MS in the same patient have thus far been described. We describe here a 29-year-old woman in whom MS developed in 1983 and CD in 1989. The MS may have been the result of a strongly HLA-associated genetic predisposition, while the additional development of CD may have been due either to genetic factors or perhaps simply to chance. Viewing this case in the context of epidemiological data, however, we suggest that the development of CD and MS is based on one or more common genetic factors acting in conjunction with other presumably exogenous factors and triggering HLA antigens to lead to one disease or the other.

Adult↗
PubMed1991

[Various genetic models in Crohn disease].

Crohn's disease has a genetic predisposition. In the light of epidemiological data, especially the type of familial clustering, simple modes of inheritance can be excluded. At the first glance, our results implied a polygenic multifactorial basis. Further processing of our data by the "mixed model" of Morton revealed a higher probability for a recessive gene with low penetrance. However, the differences in fit between the various models are relatively slight. Also considering ascertainment problems, a definite decision concerning an appropriate model must be deferred until sure genetic markers have been identified. Nevertheless, only a certain number of manifestations may be ascribed to a genetic predisposition, others have to be catagorized as phenocopies.

Adolescent↗
PubMed1990

Gene and haplotype frequencies of HLA antigens in 269 patients with Crohn's disease.

Evidence of strong genetic markers in Crohn's disease (CD) is still absent. Many investigations have focused on HLA antigens, with conflicting results. To obtain more detailed information on the relation of HLA to the disease, we used the HLA data from 269 CD patients to compute the maximum-likelihood estimates of HLA gene and haplotype frequencies. These results provide further evidence that HLA B44 and Cw5 do indeed play a role in the development of CD. Furthermore, it is conceivable from our results that HLA Cw7 may protect against being affected with this disease.

Chi-Square Distribution↗
PubMed1990

[T-lymphocyte subpopulations in the peripheral blood of patients with Crohn disease].

Immunological disorders seem to be of considerable relevance to the pathogenesis of Crohn's disease (CD). T-cells play a central role in immunoregulation. The T-cell subpopulations of 70 patients with CD were compared to those of age- and sex-matched healthy controls. The suppressor-inducer subpopulations were found to be reduced in CD patients irrespective of wether they were taking steroids or not. In contrast to other subpopulations suppressor-inducer cells remained unchanged during follow-up. The results point to a disturbance in the regulation of suppressor T-cells in patients with Crohn's disease.

Adrenal Cortex Hormones↗
PubMed1990

Crohn's disease in four members of a family, two of whom are dizygotic twins.

Familial occurrence of Crohn's disease (CD) is well known, but the disease is rarely reported to occur in dizygotic twins. We present an additional case of dizygotic twins, both of whom developed CD, from a family in which two other members are affected. The 16-year-old son contracted the disease 2 years before his 50-year-old father, and 13 years before his twin sister. Another sister was affected 6 years after the onset of the disease in the propositus. HLA haplotyping of the three children matched the Mendelian ratio. The multiple occurrence of CD in blood relatives, especially in siblings, emphasizes the importance of genetic factors in the development of this disease. This family history, however, could point to psychic influences promoting the occurrence of CD on the basis of a polygenic disease susceptibility.

Adolescent↗
PubMed1989

On the construction of cross-sectional statistical standards for growth.

Cross-sectional growth studies generally produce standardizing groups which are too small to permit the direct construction of standards. This problem can be circumvented by the introduction of appropriate structural assumptions. The two key papers in the literature which focus on this issue, Healy (1962) and Goldstein (1972), give methodologies which involve somewhat different premises. Healy takes the ages of individuals to be uniformly distributed over a well-defined interval (but their precise levels unknown). Goldstein by comparison supposes age levels to be known exactly. Both authors postulate that the characteristic of interest follows a Gaussian density whose mean and variance are each linear functions of time, a + bt and c + dt, say. In this paper we begin to explore the robustness of the two methods. Our results show that Healy's original moment solution to the estimation of (a, b, c and d) may be quite insensitive to departures from a uniform distribution for ages provided that this distribution remains symmetric about the interval mid-point. Moreover, the distribution of the characteristic of interest may deviate from the Gaussian without too much effect, provided that symmetry about the mean a + bt is retained. However, there is much more doubt about asymmetric departures in both cases especially with regard to the estimation of b and d. Opting for simple 'interpolated' estimates of these two parameters (when possible) rather than Healy's original formula-based versions will strongly aid robustness in general.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1989

Commitment: the consistency of clinicians and the use of legal standards.

The reliability and validity of the application of legal criteria for commitment were investigated as part of a larger study. Evaluations of 411 patients by 96 different clinicians showed good interrater reliability for assessment of dangerousness and committability. A strong relationship between ratings of committability and ratings of dangerousness suggests that clinicians were conforming to the logic of the commitment law. Discrepant cases involved patients who desired voluntary admission or whose commitment was completed elsewhere. Results suggest fair application of commitment standards but that two issues of statutory interpretation confused participating clinicians.

Commitment of Persons with Psychiatric Disorders↗
PubMed1989

Do dangerousness-oriented commitment laws restrict hospitalization of patients who need treatment? A test.

A study at a large urban psychiatric hospital in Pennsylvania evaluated whether the state's dangerousness-oriented commitment criteria restricted hospitalization of patients whom emergency room clinicians considered highly in need of treatment but not dangerous. A total of 390 patients were studied. Eleven patients judged to be highly in need of treatment did not meet any of the commitment criteria, but they were largely compliant with the idea of being treated. An additional 17 patients considered highly in need of treatment met criteria for commitment based on inability to care for self, but most were hospitalized voluntarily. Only one patient who met none of the commitment criteria resisted recommended hospital care, and she was eventually committed involuntarily based on inability to care for self. The data suggest that dangerousness-oriented commitment criteria are flexible enough to provide for treatment of patients in serious need.

Activities of Daily Living↗
PubMed1989

Investigation of genetic markers in patients with Crohn's disease and ulcerative colitis.

Inflammatory bowel diseases (IBD) as Crohn's disease (CD) and ulcerative colitis (UC) are believed to have a genetic basis. Additional factors are supposed to promote the development of IBD. However, apart from a few reports of HLA associations which await confirmation by other groups strong associations to (a) particular genetic marker(s) are still lacking. We here report on previously unobserved associations of CD to MNSS and UC to the immunoglobulin heavy chain allotype Gm 1,-2,10. We suggest that these factors play a role in a wider spectrum of genetic markers for the development of IBD.

Acid Phosphatase↗
PubMed1988

Association of Crohn's disease with HLA phenotype B44, Cw5.

Genetic influence on the development of Crohn's disease (CD) is commonly accepted. However, proof of definite genetic markers is still pending. Most investigations have focused on HLA antigens, and associations with HLA B12 and HLA A2 have been reported, but the design of these retrospective studies is open to criticism. We have undertaken a consecutive study of 96 patients with CD under well-defined conditions in order to test the hypothesis that CD is associated with particular HLA antigens. Our results identify a significant association of CD with the phenotype HLA B44,Cw5. But since a major proportion of the CD patients do not bear this phenotype, other predisposing genetic factors, which have not yet been defined, may exist in addition to environmental factors.

Adolescent↗