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Biomedical subjects

J Hamilton

Publications and source records attributed to J Hamilton.

At least 37 records · Page 2Linked to original sources
PubMed1998

Methodological issues in evaluating a culture-based substance abuse treatment program in the Kuskokwim Delta, Alaska.

This paper presents a rationale for using videotape records in evaluation research. Although videotaping is commonly used in ethnographic and sociometric analysis, the evaluation literature does not show the application of these recording techniques to program evaluations. The authors outline a model for exploring the effectiveness of video in qualitative program evaluation.

Alaska↗
PubMed1998

MR imaging in idiopathic growth hormone deficiency.

BACKGROUND AND PURPOSE: MR imaging findings of one or more of the following has been suggested to be a sensitive and specific indicator of hypopituitarism: small anterior pituitary gland, attenuated or absent pituitary stalk, and ectopic posterior pituitary. We hypothesized that these MR findings would be common in our group of patients with idiopathic isolated growth hormone deficiency (GHD) or multiple pituitary hormone deficiencies (MPHD) and would be a good indicator of the severity of the hypopituitarism. METHODS: MR images were obtained for 35 patients with idiopathic GHD (20 with isolated GHD and 15 with MPHD; age range, 2 to 17 years) and analyzed to define one or more of the following triad of abnormalities: 1) small/absent anterior pituitary, 2) truncated/absent pituitary stalk, and 3) ectopic posterior pituitary, as well as for any other associated anomalies. The findings were correlated with the clinical and biochemical presentation. RESULTS: Pituitary abnormalities were common in both groups (80% with isolated GHD, 93% with MPHD). We found a high frequency of midline CNS malformations, including optic nerve hypoplasia (9%), Chiari type I malformations (20%), and medial deviation of the carotid arteries (37%). Breech delivery, neonatal hypoglycemia, jaundice, micropenis, or single central incisor occurred equally with both isolated GHD and MPHD. In patients whose peak growth hormone level was less than 3 microg/L (n = 19), 90% had the MR triad, compared with 390% of those with growth hormone levels 3 microg/L or greater or less than 8 microg/L (n = 13) (P <.01). Almost all (92%) of those with ectopic posterior pituitary had anterior pituitary heights less than -2 SD for age. CONCLUSION: MR abnormalities were common in children with both isolated GHD and MPHD and were closely associated with peak growth hormone levels less than 3 microg/L. The presence of other CNS and clinical findings (eg, single central incisor and micropenis) supports the theory of an embryologic defect as the cause of the pituitary abnormalities.

Adolescent↗
PubMed1997

Transcutaneous partial oxygen pressure changes following skew flap and Burgess-type below-knee amputations.

OBJECTIVE: To evaluate the degree of flap hypoxia following different types of below-knee amputations. DESIGN: Prospective preoperative and postoperative measurements of transcutaneous partial oxygen pressure (TcPo2) at the site of amputation in 10 consecutive patients who underwent a Burgess-type below-knee amputation (group 1) and in 10 consecutive patients who underwent a skew flap amputation (group 2). SETTING: An academic, tertiary care Veterans Affairs medical center. PATIENTS: Individuals with severe arterial occlusive disease of the lower extremity, in many of whom vascular reconstruction has failed. INTERVENTION: Measurements of TcPo2 (in millimeters of mercury). MAIN OUTCOME MEASUREMENT: The decrease in TcPo2 associated with the different "flaps" of a Burgess-type below-knee amputation. RESULTS: In all skin flaps, regardless of the type of amputation, an early postoperative reduction of the TcPo2 was noted. The greatest reduction (11 mm Hg) and persistence at 20 postoperative days were noted in posterior flaps. CONCLUSIONS: Strict conformity to the Burgess-type of below-knee flap design may not provide an optimal incisional blood supply. Consideration should be given to the skew flap technique in patients who require amputation for severe lower limb arterial insufficiency.

Aged↗
PubMed1997

Comparison of the infectivity of the laboratory strain AD169 and a clinical isolate of human cytomegalovirus to human smooth muscle cells.

The results displayed by human cytomegalovirus (HCMV) IE/E antigen expression and virus release into the supernatant at various times post infection with a clinical isolate (C3/p5) and AD169 laboratory strain of HCMV, illustrated differences in the biology of these viruses on the various cell lines. While AD169 strain was shown to infect fibroblasts efficiently, it showed a low infectivity profile to smooth muscle cells, whereas C3/p5 displayed comparable infectivity characteristics on both cell lines. Neither virus demonstrated propensity for infecting endothelial cells, although passaging of the C3/p5 for additional 11 passages in endothelial cells provided virus capable of infecting endothelial cells efficiently. These results show that HCMV is capable of infecting smooth muscle cells which could be of relevance to the proposed role of HCMV in atherogenesis and provides further evidence on the adaptation of AD169 to fibroblasts.

Adaptation, Physiological↗
PubMed1997

Mandibular invasion in patients with oral and oropharyngeal squamous carcinoma.

Invasion of the mandible in squamous carcinoma of the oral cavity and oropharynx has always proved a problem for head and neck oncologists. We studied 82 patients who had mandibulectomies as part of their primary surgical treatment for cancer of these sites. In 40 patients, the tumour appeared to be invading the mandible on clinical grounds and 33 patients had tumours invading the mandible when the latter was examined histopathologically. Multivariate analysis showed that tumour was more likely to be fixed to and clinically invading the mandible in the presence of cancer of the oral cavity, compared with oropharyngeal cancer (P < 0.0001). There was a high degree of correlation between clinical invasion of the mandible and histopathological invasion of the mandible (P = 0.0059). In addition, clinical invasion of the mandible correlated with radiological findings (P = 0.0284). The 5-year survival of those patients with tumour that appeared not to be invading the mandible was 53% compared with 25% for those where tumour did appear to be invading the mandible (P < 0.02). The sensitivity and specificity of clinical evidence of mandibular invasion was calculated with the final arbiter of invasion being the histopathological findings. The sensitivity of clinical examination was 91% and the specificity 80%. The positive predictive value was 75% and the negative predictive value 93%. Mandibular invasion is a poor prognostic sign in cancer of the oropharynx and oral cavity. Detection of invasion prior to operation is obviously extremely important and it appears that clinical findings are an accurate method of predicting invasion.

Adult↗
PubMed1996

Benzoporphyrin derivative decreases the binding of low density lipoprotein to the glycosaminoglycan chondroitin-6-sulfate in vitro.

We have investigated the effect of the hydrophobic photosensitizer (PS), benzoporphyrin derivative (BPD), on low density lipoprotein (LDL) binding to the glycosaminoglycan (GAG), chondroitin-6-sulfate (C-6-S) in vitro. Agarose electrophoresis of the BPD-LDL complexes indicated that ratios of 50 ng BPD per microgram LDL protein and above displayed increased net negative charge. Ratios less than 10 ng BPD per microgram LDL protein slightly increased the association of the LDL with the C-6-S. Ratios of 10 ng BPD per microgram LDL protein and greater decreased the association between LDL and GAG in a BPD concentration dependent manner. Since the retention of LDL by the extracellular matrix (ECM) GAG in the artery wall is a key event in atherogenesis, the reported effects of BPD on LDL binding to C-6-S may be of interest.

Chondroitin Sulfates↗
PubMed1996

Multicultural health care requires adjustments by doctors and patients.

Canada has become a multicultural society, and more physicians have patients who are immigrants or refugees from the Third World. While doctors are aware of the need for culturally sensitive health care, there is still room for improving the delivery of medical treatment to those of other cultures. Janice Hamilton spoke with physicians who have multicultural practices to get an idea of the challenges they have faced and the problems they have solved.

Attitude to Health↗