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Biomedical subjects

D Myers

Publications and source records attributed to D Myers.

At least 91 records · Page 5Linked to original sources
PubMed1967

1,2-3-H cholesterol as a tracer in studies of human cholesterol metabolism.

1,2-(3)H-Cholesterol was fed to a subject together with 4-(14)C-cholesterol at a known (3)H/(14)C ratio. The ratio was satisfactorily preserved in cholesterol recovered from plasma, red cells, and bile, and in bile acids of bile. Isotopic fractionation was seen during thin-layer chromatographic isolation of cholesterol. In work with 1,2-(3)H-cholesterol or its metabolites care should be taken to recover chromatographic bands in their entirety.

Bile↗
PubMedDate not supplied

Advanced Merkel cell cancer and the elderly.

BACKGROUND: Merkel cell cancer (MCC) is an uncommon neuroendocrine skin cancer occurring predominantly in elderly Caucasians. It tends to metastasize to regional lymph nodes and viscera and is sensitive to chemotherapy but recurs rapidly. AIM: To report one such case, its response to chemotherapy and briefly review the literature. METHODS: A 73-year-old male with a fungating primary lesion on his left knee and ulcerated inguinal lymph nodes was diagnosed with MCC and treated with chemotherapy. The two largest case series and reviews of case reports were summarised. RESULTS: His ulcer healed after two cycles of carboplatin and etoposide with improvement in quality of life. Overall response rates of nearly 60% to chemotherapy are reported but median survival is only nine months with metastatic disease. CONCLUSIONS: Chemotherapy should be considered for fit elderly patients with MCC who have recurrent or advanced disease.

Aged↗
PubMedDate not supplied

Short-term effects of formaldehyde on peak expiratory flow and irritant symptoms.

The authors studied the respiratory effects of formaldehyde exposure among students who dissected cadavers in a gross anatomy laboratory. Peak expiratory flow and respiratory symptoms were measured before and after each weekly laboratory session. Each of 38 students was exposed to formaldehyde for 2.5 hr/wk for 14 wk. Individual, daily formaldehyde measurements averaged 1.1 ppm (standard deviation = 0.56 ppm). Multivariate models demonstrated two different time scales of effect of formaldehyde on peak expiratory flow: (1) exposure during the previous 2.5 hr reduced peak expiratory flow by -1.0% per ppm, and (2) average exposure during all preceding weeks reduced peak expiratory flow by an additional -0.5% per ppm of formaldehyde. However, the short-term exposure effect was diminished during the first 4 wk, suggesting at least partial acclimatization. Symptom reporting was also associated with exposure during the previous 2.5 hr, and similar evidence of acclimatization was observed. These results suggest that there are two different time scales of response to formaldehyde, and they emphasize the need for longitudinal studies, characterized by quantitative exposure characterization, and frequent measurements of outcome.

Acclimatization↗
PubMedDate not supplied

The use of multivariate methods in the identification of subtypes of Alzheimer's disease: a comparison of principal components and cluster analysis.

Two contrasting multivariate statistical methods, viz., principal components analysis (PCA) and cluster analysis were applied to the study of neuropathological variations between cases of Alzheimer's disease (AD). To compare the two methods, 78 cases of AD were analyzed, each characterised by measurements of 47 neuropathological variables. Both methods of analysis revealed significant variations between AD cases. These variations were related primarily to differences in the distribution and abundance of senile plaques (SP) and neurofibrillary tangles (NFT) in the brain. Cluster analysis classified the majority of AD cases into five groups which could represent subtypes of AD. However, PCA suggested that variation between cases was more continuous with no distinct subtypes. Hence, PCA may be a more appropriate method than cluster analysis in the study of neuropathological variations between AD cases.

Aged↗
PubMedDate not supplied

The spatial patterns of plaques and tangles in Alzheimer's disease do not support the 'cascade hypothesis'.

In Alzheimer's disease (AD), the 'Cascade hypothesis' proposes that the formation of paired helical filaments (PHF) may be casually linked to the deposition of beta/A4 protein. Hence, there should be a close spatial relationship between senile plaques and cellular neurofibrillary tangles in a local region of the brain. In tissue from 6 AD patients, plaques and tangles occurred in clusters and individual clusters were often regularly spaced along the cortical strip. However, the clusters of plaques and tangles were in phase in only 4/32 cortical tissues examined. Hence, the data were not consistent with the 'Cascade hypothesis' that beta/A4 and PHF are directly linked in AD.

Aged↗
PubMedDate not supplied

The ratio of diffuse to mature beta/A4 deposits in Alzheimer's disease varies in cases with and without pronounced congophilic angiopathy.

The density of diffuse, primitive, classic and compact beta/A4 deposits was estimated in the cortex and hippocampus in Alzheimer's disease (AD) cases with and without pronounced congophilic angiopathy (CA). The total density of beta/A4 deposits in a given brain region was similar in cases with and without CA. Significantly fewer diffuse deposits and more primitive/classic deposits were found in the cases with CA. The densities of the primitive, classic and compact deposits were positively correlated in the cases without CA. However, no correlations were observed between the density of the mature subtypes and the diffuse deposits in these cases. In the cases with CA, the density of the primitive deposits was positively correlated with the diffuse but not with the classic deposits. The data suggest that the mature beta/A4 deposits are derived from the diffuse deposits and that the presence of pronounced CA enhances their formation.

Aged↗
PubMedDate not supplied

Antibody coated bacteria in otitis media with effusions.

The significance of bacterial isolates of coagulase negative Staphylococcus epidermidis and Corynebacterium species in middle ear fluids remains controversial. This study was undertaken to evaluate the possible role of these organisms in different effusions. Cultures were obtained from the external cartilaginous ear, bony canal, tympanic membrane, middle ear fluids, tonsils and nasopharynx of 93 patients at the time of myringotomy for otitis media with effusion. Isolates of coagulase negative staphylococci from the middle ear, external ear and posterior aural skin were evaluated in regard to antibiotic sensitivity, biochemical tests and phage typing. Furthermore, in another series of patients in whom these organisms were isolated, specific antibody activity in both middle ear washings and corresponding sera were measured, using the technique of indirect immunofluorescence. The results suggest that the isolates from the middle ear and ear canal are not always identical. There is some evidence that specific IgM and IgG as well as IgA responses to these organisms are present in middle ear washings and not in corresponding serum. These results suggest that coagulase negative Staphylococcus and Corynebacterium species in middle ear effusions may not be contaminants from the external canal and that a local immune response may be produced by these organisms. Whether or not these organisms represent etiologic agents responsible for otitis media with effusion cannot be ascertained from this data. One very interesting point is the presence of IgF coating of organisms in some effusions.

Adolescent↗
PubMedDate not supplied

Platypus envenomation--a painful learning experience.

OBJECTIVE: To describe in detail for the first time, the clinical course and medical management of a significant human envenomation by the Australian platypus (Ornithorhynchus anatinus). CLINICAL FEATURES: A 57-year-old man was envenomated via two spur wounds to the right hand from each hind leg of a male platypus. Pain was immediate, sustained, and devastating; traditional first aid analgesic methods were ineffective. INTERVENTION AND OUTCOME: On admission to hospital, narcotics administered intravenously, both intermittently and by infusion, provided inadequate analgesia. A right wrist block was dramatically effective. After the blockade narcotic analgesic support was required for several days. The patient spent six days in hospital, and the envenomated area remained painful, swollen and with little movement for three weeks. Significant functional impairment of the hand persisted for three months, the cause of which is uncertain. CONCLUSIONS: Male platypus venom remains largely unstudied. It produces savage local pain and marked local swelling, but no apparent tissue ischaemia. No antivenom is available; in its absence the only effective analgesia appears to be regional nerve blockade, when the envenomation site and available skills permit. Immobilisation assists.

Animals↗
PubMedDate not supplied

Psychological and behavioral dynamics in chronic atypical facial pain.

The authors discuss the relationship between atypical facial pain and psychiatric disturbance. They present contemporary viewpoints and describe four cases that illustrate underlying psychodynamic mechanisms associated with pain in patients who had undergone various dental procedures and other treatments without success. They identify factors which might lead to the early detection of underlying psychological problems and discuss the role of learning, the family system and other factors in producing a chronic pain syndrome.

Adult↗