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Biomedical subjects

J Hamilton

Publications and source records attributed to J Hamilton.

At least 73 records · Page 4Linked to original sources
PubMed1996

Electromagnetic interference can cause hospital devices to malfunction, McGill group warns.

Electromagnetic interference (EMI) from sources such as television transmitters, police radios and cellular phones can cause medical monitors and other hospital devices to malfunction, says the principal investigator of a McGill biomedical engineering group set up in 1989 to study, predict and prevent such problems. The impact of equipment malfunction can range from mere inconvenience to serious problems. The research group advises physicians and other health care professionals to learn how to spot problems related to EMI and electromagnetic compatibility.

Electromagnetic Fields↗
PubMed1996

Post-prostatectomy incontinence: urodynamic findings and treatment outcomes.

PURPOSE: We examined urodynamic findings and treatment outcomes in a large population of men with post-prostatectomy incontinence. MATERIALS AND METHODS: A total of 215 men was referred for evaluation and treatment of significant post-prostatectomy incontinence. Urodynamic evaluation consisted of provocation multichannel medium fill cystometry with vigorous attempts to demonstrate incontinence. Treatment was directed by the results of the urodynamic study. A pad scoring system was used to gauge the severity of incontinence before and after treatment. RESULTS: Based on the results of urodynamic studies 40% of the men had genuine stress incontinence alone and approximately 60% had a major component of bladder dysfunction contributing to incontinence. Treatment results of 135 men demonstrated a significant decrease in pad score (p<0.001) for those treated with anticholinergics, those undergoing artificial sphincter insertion and those treated pharmacologically before sphincter placement. CONCLUSIONS: In our large series most men with prostatectomy incontinence did not have genuine stress incontinence alone. Thus, urodynamic studies are critical, not only to define cause of incontinence but to direct effective therapy.

Aged↗
PubMed1996

The national lesbian family study: 1. interviews with prospective mothers.

This first report from a longitudinal study of 84 lesbian families, 70 of which include a co-mother as well as a birthmother whose child was conceived by donor insemination, presents interview data on parental relationships, social supports, pregnancy motives and preferences, stigmatization concerns, and coping strategies. Methodological limitations of studying this special population are noted, and plans for follow-up interviews over the course of 25 years are outlined.

Adaptation, Psychological↗
PubMed1996

Malignant tumours of the cervical oesophagus.

Forty-seven patients with malignancy of the cervical oesophagus are described and compared with a group of 647 patients with hypopharyngeal malignancy. There was a higher proportion of non-squamous malignancy in cervical oesophageal cancer compared with hypopharyngeal cancer. Cervical oesophageal malignancy tended to present earlier with significantly lower T stage and neck node metastases were relatively unusual at presentation. Patients with cervical oesophageal malignancy were frequently incurable at the time they are first seen and 21 had palliative treatment only, 26 patients had curative treatment, 12 underwent radical radiotherapy and 14 had surgery. Cervical oesophageal malignancy had a significantly worse prognosis than hypopharyngeal malignancy with an 18% 3 year survival compared with a 33% 3 year survival (chi (1)2 = 7.1089, P < 0.01). Those patients with oesophageal malignancy who were treated fared considerably better than the whole group with 30% being alive at 3 years (chi (1)2 = 10.5185, P < 0.01).

Carcinoma, Squamous Cell↗
PubMed1996

Raising airway resistance in laryngectomees increases tissue oxygen saturation.

The physiological airflow resistance from the anterior nares to the upper trachea has recently been documented. This resistance is thought to be important in preventing alveolar collapse and in maintaining the optimum lung ventilation: perfusion ratio. This resistance is lost in laryngectomees who may have a subsequent decline in lung function and arterial oxygen saturation. A stoma filter with a resistance approximating to that of the normal upper airway has been developed and laryngectomees who wear this device demonstrate a rapid increase in tissue oxygen saturation (median increase: 1.4 kPa, P = 0.0087) without significantly altering tissue carbon dioxide saturation. This finding will have a major impact on the future rehabilitation of laryngectomees and those with a temporary tracheostomy.

Airway Resistance↗
PubMed1996

Interleukin-11 mRNA stabilization in phorbol ester-stimulated primate bone marrow stromal cells.

12-O-Tetradecanoylphorbol-13-acetate (TPA) stimulation of PU-34 cells, a primate bone marrow stromal cell line, resulted in a prolonged elevation of interleukin-11 (IL-11) mRNA, which can be inhibited by protein synthesis inhibitors. Nuclear run-on assays and actinomycin D experiments demonstrated that the up-regulation of IL-11 gene expression is mainly controlled at the posttranscriptional level through the protein kinase C (PKC) pathway. Inhibition of PKC activity by calphostin C generated an IL-11 mRNA degradation intermediate in TPA-stimulated PU-34 cells. This intermediate retains the 5' untranslated region (5'UTR) and coding region of the IL-11 mRNA but has lost the poly(A) tail and the 3'UTR. The mechanisms underlying IL-11 mRNA stabilization were further investigated by transfections with a variety of chimeric IL-11 constructs and deletion mutants. Two important observations were made from these transient expression experiments: (i) the same 3'UTR of IL-11 mRNA shown to confer instability in one chimeric transcript may not function as a destabilizer in another chimeric RNA, and (ii) the 5'UTR, coding region, and 3'UTR all contribute to IL-11 mRNA decay, and labile IL-11 deletion transcripts are not necessarily stabilized by TPA stimulation. Our study suggests that multiple regions within the IL-11 mRNA are involved in TPA-stimulated IL-11 mRNA stabilization, possibly through a unique RNA folding conformation involving interactions of various RNA sequences within the IL-11 mRNA molecule.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1996

Alterations of lipolysis and lipoprotein lipase in chronically nicotine-treated rats.

These studies examined the cellular mechanisms for lower adiposity seen with nicotine ingestion. Rats were infused with nicotine or saline for 1 wk and adipocytes isolated from epididymal fat pads. Nicotine-infused rats gained 37% less weight and had 21% smaller fat pads. Basal lipolysis was 78% higher, whereas the maximal lipolytic response to isoproterenol was blunted in adipocytes from nicotine-infused rats. The antilipolytic actions of adenosine and the levels of serum catecholamines were unaffected by nicotine. The nicotine-induced alteration in lipolysis was not associated with any changes in hormone-sensitive lipase. Nicotine caused a 30% decrease in lipoprotein lipase (LPL) activity, without any changes in LPL mass or mRNA levels, in epididymal fat in the fed state. In contrast, LPL activity, mass, and mRNA levels in heart were increased by nicotine whether animals were fed or fasted. These studies provide evidence for multiple mechanistic events underlying nicotine-induced alterations in weight and suggest that nicotine diverts fat storage away from adipose tissue and toward utilization by muscle.

Adipose Tissue↗
PubMed1995

Premature babies and pharmacology.

In his research on the action of various drugs in newborns, Dr. Jacob Aranda of the Centre for Perinatal and Developmental Pharmacology Research in Montreal draws upon his expertise in both neonatology and pharmacology. His work has led to the acceptance of caffeine as a standard treatment of apnea in premature infants, and his current studies of ibuprofen as a possible treatment of cerebral intraventricular hemorrhage, a serious problem in some premature babies, have yielded promising results. Other areas being tackled by Aranda and his colleagues include pain control for newborns and the elusive pathology of sudden infant death syndrome. By shedding more light on neonatal development and the principles of drug action in newborns, these research projects will help to improve the odds for many babies who suffer the setback of being born too soon.

Anesthetics, Local↗
PubMed1995

Montreal Museum exhibit provides clear picture of advances in medical imaging.

An exhibit at the McCord Museum of Canadian History, which runs until November, marks the centennial of the discovery of the x-ray. Among the items on display are a portable field x-ray machine used during World War I and one of the machines commonly found in shoe stores between 1930 and 1950 to x-ray customers' feet. The exhibit also features one of the first scanners used in North America. Dr. Denis Melançon, a radiologist at the Montreal Neurological Institute, was the driving force behind the McCord exhibit. "I wanted to show [not only] the historical and scientific aspects of the discovery, but also its medical and social applications," he says.

Exhibitions as Topic↗
PubMed1995

A question of rhythm: recent advances in growth hormone research.

Research by Dr. Gloria Shaffer Tannenbaum at the McGill University-Montreal Children's Hospital Research Institute has led to the development of a new test to differentiate children who are deficient in growth hormone from those who are short but growing normally. This clinical application is the fruit of Tannenbaum's discovery that growth hormone secretion occurs in a rhythmic pattern regulated by intricate interactions between two neurohormones: growth hormone-releasing hormone (GHRH) and somatotropin release-inhibiting factor (SRIF). In the test an analogue of SRIF is used to allow stores of growth hormone to build up. A subsequent challenge with GHRH is then used to identify children with a genuine deficiency. Tannenbaum's research also indicates that there are sexual differences in the pattern of growth hormone release and that growth hormone regulates its own secretion by means of a negative feedback system.

Growth Disorders↗
PubMed1995

Dr. Balfour Mount and the cruel irony of our care for the dying.

Dr. Balfour Mount of Montreal thinks that the health care system, because of its fixation on disease processes, may have forgotten that it also has a mandate to alleviate suffering. "We need to recapture that vision," says Mount, who describes palliative medicine as a "rich combination" of clinical pharmacology, rehabilitation medicine and internal medicine. Mount says there is a cruel irony in our care of the dying. "Although these are the sickest people in our health care system, when medical technology doesn't know what to do, the quality and quantity of care falls away. How can we justify that?"

Canada↗
PubMed1995

Organization for rural MDs focuses "on problems that separate us from our urban counterparts".

Physicians in rural Canada face much different problems than their counterparts in large cities, a recent conference for rural physicians was told. For instance, rural areas may be decimated by funding caps because "they didn't have any resources to give up in the first place," said Dr. Ken Babey. He said rural physicians don't want to create divisiveness between urban and rural doctors, "but people don't realize that when they do something that has a big impact on the doctors who practise in cities and suburban areas, it has a disastrous impact on us." Rural doctors are attempting to organize so they can present a united front; in Nova Scotia, physicians recently formed a Section of Rural Practice.

Canada↗
PubMed1995

Ingestive response shows absence of taste aversion after bovine satietin in rats.

Six adult male rats (409 +/- 16 g) were equipped with chronically implanted oral catheters. Facial consummatory responses to gustatory stimuli, of 50 microliters 2.0 mol.1-1 banana or coconut flavoring, were recorded on a +4/-4 scale for 30 s. The new flavors were paired with IP injections on three different days. The rats were injected with either saline or 1 mg.kg-1 bovine serum satietin (bs-SAT). Food intake and body weight were reduced (p < 0.005) after satietin but not after saline. Both coconut and banana flavors aroused mild ingestive responses in the naive rats. Five days after the beginning of the pairing with IP injections, the rats' response to coconut and banana remained unchanged. The results show that satietin was able to reduce food intake and body weight but did not arouse taste aversion.

Animals↗
PubMed1995

Modified Pereyra bladder neck suspension: 10-year mean followup using outcomes analysis in 125 patients.

PURPOSE: We attempt to determine the long-term success rate of the modified Pereyra bladder neck suspension, identify preoperative factors predictive of long-term outcome, and investigate the influence of method and length of followup on reported continence status after modified Pereyra bladder neck suspension. MATERIALS AND METHODS: The charts of 177 patients who underwent modified Pereyra bladder neck suspension at our institution more than 5 years ago were reviewed. An attempt was made to contact all patients either by mail or telephone to complete a patient survey questionnaire. RESULTS: Of 177 patients 125 (71%) completed the patient survey with a mean followup of 9.8 years. At survey followup 20% of the patients reported no incontinence of any type and 51% reported stress urinary incontinence with or without urge incontinence. Of the patients 71% reported significant improvement in the incontinence and 73% were satisfied with the results of the procedure. No accurate preoperative predictors of long-term outcome were identified. The method and length of followup had significant impact on reported continence status after modified Pereyra bladder neck suspension. CONCLUSIONS: This long-term study using outcomes analysis reveals a high rate of recurrent stress incontinence after modified Pereyra bladder neck suspension. However, most patients maintain significant subjective improvement and remain satisfied with the results of the operation.

Female↗
PubMed1995

The treatment of node negative squamous cell carcinoma of the postcricoid region.

This study includes 155 patients with T1-4N0 carcinoma of the postcricoid region seen between 1963 and 1993. Sixty-seven were treated by primary surgery, 50 by primary irradiation therapy, 36 were unsuitable for curative treatment and two patients were lost to follow-up. Reasons for deciding against curative therapy were: advanced age, poor general condition and advanced disease at the primary site. This study included only those patients who had no neck node metastases at presentation. Patients receiving surgery tended to be in better general physical condition and tended to have more advanced disease than those treated by irradiation in this series. The tumour-specific five-year survival rate for those treated by surgery was 43 percent (95 percent confidence interval (CI) 23-60 percent). For those patients treated by irradiation the five-year survival rate was 48 percent (95 percent CI 27-66 percent) and for those receiving no treatment the median survival rate was three months (95 percent CI two-six months). The observed survival for the surgery group was only 18 percent and for the radiotherapy group 25 percent at five years. Multiple logistic regression showed no significant difference in proportions of host and tumour factors between the group receiving radiotherapy and the group receiving surgery. Recurrence at the primary site and the appearance of neck node metastases were not predicted by any host or tumour factor. Twenty-one patients out of 67 receiving primary surgery had recurrence at the primary site compared with 26 patients out of 50 receiving primary irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗