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Biomedical subjects

S M Hamilton

Publications and source records attributed to S M Hamilton.

At least 19 recordsLinked to original sources
PubMed2004

Gastric cancer: establishing predictors of biologic behavior with use of population-based data.

BACKGROUND: Tumor thickness and nodal status are important predictors of survival following curative resection for gastric cancer. Lymphovascular invasion (LVI) is a potential predictor of biological behavior. The relationship between LVI and tumor thickness (T status) has not been established in population-based studies. METHODS: Clinicopathological and survival data of 577 patients at nine centers, from between 1991 and 1997, was collected from patient records and a Provincial Cancer Registry. The primary endpoint of the study was death. A secondary analysis of a node-negative subgroup examined the significance of LVI with respect to T status. RESULTS: The population disease-specific survival was 28%. In a multivariate analysis, T, N, M, esophageal margin, tumor morphology, and residual tumor category were independent predictors of survival. LVI was documented in 58% of resected tumors. LVI correlated with advancing T and N status but was not significant in a multivariate population model. Subgroup analysis of node-negative gastric cancer found T status and LVI to be independent predictors of survival. LVI was associated with a 5-year survival of 8%, versus 43% among patients in whom it was absent (P <.001). CONCLUSIONS: T status and N status were the most important independent predictors of survival in a population-based study of gastric cancer. LVI correlated with advancing N and T status. Multivariate analysis of node-negative patients showed LVI and T status are independent predictors of survival.

Adenocarcinoma↗
PubMed2001

Outcomes after the regionalization of major surgical procedures in the Alberta Capital Health Region (Edmonton).

OBJECTIVE: To evaluate the impact of regionalization on the outcomes of 16 surgical procedures performed in the Capital Health Region (Edmonton) of Alberta. DESIGN: A computer search of hospital discharge abstracts coded for the Canadian Institute for Health Information. SETTING: Two major hospitals in Edmonton. PATIENTS: The study population comprised 9250 patients (9727 procedures [4524, pre-regionalization, 5203 post-regionalization]) who underwent any of 16 major procedures in the 2 years before and the 2 years after restructuring. OUTCOME MEASURES: Demographic data, Charlson's comorbidity index, number of urgent and emergent cases, death rate, average length of hospital stay and the readmission rate. RESULTS: The post-regionalization patient group was slightly older, had a higher comorbidity index, and fewer urgent and emergent cases. The case volume increased by 15%, and 43.6% of patients used some form of community-based health care services. The median length of hospital stay decreased from 8.0 days pre-regionalization to 7.0 days post-regionalization (p < 0.001). Overall and for specific procedures the death rate was unchanged (3.1% pre-regionalization, 2.4% post-regionalization, p = 0.06). The readmission rates were similar for both groups (8.0% versus 7.0%). CONCLUSIONS: The consolidation of these 16 major surgical procedures had minimal impact on death and readmission rates even though patients in the post-regionalization group were slightly older and had greater comorbidity. There was a significant decline in the length of hospital stay, which occurred nationally over the same period, and a corresponding increase in the use of community-based services.

Adult↗
PubMed1999

Antenatal screening by history taking--a missed opportunity.

In order to determine how effectively obstetricians and midwives identify and manage women at increased risk of fetal abnormality a case note review was undertaken. Two district general hospitals in each of two health regions and their tertiary referral centres making seven hospitals in all were studied. Women booked for antenatal care over a one-year period were included (19 895) which was estimated to be 75% of the total. Significant numbers of women at high risk because of age, past obstetric, medical or family history were not offered appropriate tests such as detailed scanning, carrier status testing, amniocentesis or chorion villus sampling. Asian women were less likely to be offered screening compared with Caucasians. Women at low risk were subjected to inappropriate tests such as amniocentesis. Ultrasound departments were rarely informed that a woman had had a previous baby with a structural abnormality. In conclusion the quality of booking histories was poor allowing important information about past medical, family or obstetric history to be overlooked. Maternity units should use carefully structured forms taking when booking histories and all staff must have regular training on risk factors.

Journal Article↗
PubMed1997

The impact of regionalization on a surgery program in the Canadian health care system.

OBJECTIVE: To examine the impact of the regionalization of health care on the provision of surgical services in the Capital Health Region (Edmonton) of the province of Alberta. DESIGN: A 4-year retrospective descriptive analysis using data from the Canadian Institute for Health Information and from the Capital Health Region data banks. SETTING: To control health care costs, the provincially funded health care system in Alberta reformed its governance structure and service provision model. We studied community hospitals and an academic health sciences center. PATIENTS: All patients undergoing surgical care in the region. INTERVENTIONS: Regionalization of the organizational structure with the elimination of hospital boards, consolidation of services on specific sites within the regional system, and a major reduction in funding. OUTCOME MEASURES: Inpatient and day surgery procedure volumes, average length of hospital stay, relative value units, bed use, and mortality. RESULTS: The Capital Health Region has a population of 723,000 people, with 5 acute care institutions. Eighteen clinical programs now provide care through 2 referral hospitals and 3 community health centers. The reduction in operating dollars for this region was $167.1 million from fiscal years 1992-1993 to 1996-1997. Redistribution of surgical services occurred on July 1, 1995, resulting in an 18% inpatient bed reduction. Regionally, the number of acute care beds has declined from 2.25 to 1.47 per 1000 population (P < .001). Bed use has fallen from 637 to 442 inpatient days per 1000 population (P < .001). The surgery volume (1995-1996) was 44770 procedures (-3.1%). Redistribution of surgical services into high- and low-acuity settings has resulted in most surgeons working on 2 sites. Overall average length of hospital stay has decreased significantly (P < .001); however, it has increased, together with the average relative value units, in the institutions caring for patients with high-acuity surgical illnesses. Mortality remains unchanged. CONCLUSIONS: Regionalization and funding reductions within the surgical program in the Capital Health Region have resulted in a small reduction in surgical volumes. There have been major changes in service provision and the way surgeons practice.

Canada↗
PubMed1997

Pulmonary resection for lung trauma.

BACKGROUND: Pulmonary resection is rarely required for trauma, and its mortality is reportedly high. METHODS: A 10-year retrospective review of pulmonary resections for trauma was done. RESULTS: Of 2,455 patients with chest trauma, 183 (7.4%) underwent thoracotomy and 32 (1.3%) required pulmonary resection. Mean age was 28.4 years and mean injury severity score was 24.5. Mechanism of injury was stab wound in 14 patients, gunshot wound in 6, and blunt trauma in 12. Blunt trauma patients had a higher injury severity score (29.6) than penetrating trauma patients (21.4), but this was not significant (p < 0.07). Indications for thoracotomy were hemorrhage in 24 patients, airway disruption in 4, and other indications in 4. Operations consisted of wedge resection (19 patients), lobectomy (9), and pneumonectomy (4). Four (12.5%) patients (pneumonectomy, 2; lobectomy, 1; wedge, 1) died. Mortality for pneumonectomy was 50%, but this was not significantly higher than for lesser resections. Blunt trauma had a higher mortality (33%) than penetrating trauma (0%) (p < 0.02). Nonsurvivors had higher injury severity scores (44.2) than survivors (21.6) (p < 0.001). CONCLUSIONS: Pulmonary resection is infrequently required for lung injury. Overall mortality is lower than previously reported, but pneumonectomy has a high mortality. Blunt trauma has a higher mortality than penetrating trauma. Injury severity scores are higher for nonsurvivors than survivors; this shows the importance of associated injuries on outcome.

Adult↗
PubMed1995

Hemodynamic changes and gut barrier function in sequential hemorrhagic and endotoxic shock.

Multisystem organ failure (MSOF) is the major cause of late death following trauma. The gut is hypothesized to be the source of an ongoing systemic inflammatory response that drives MSOF. It has also been suggested that while a single physiologic insult might not reliably cause MSOF, the addition of a delayed second stress will. This is known as the "two-hit" theory. The purpose of this study was to investigate the two-hit theory by observing the hemodynamic and bacteriologic response to a second stress in a subacute pig model of hemorrhagic and endotoxic shock. Swine (n = 18, 30-40 kg) were fed an antibiotic-free diet for 14 days. During instrumentation and experimentation on days 1 and 3, all animals were anesthetized (ketamine, isofluorane). On day 1, all animals had placement of central venous and arterial catheters, a portal venous catheter, and superior mesenteric artery flow probe. Group E (n = 6) underwent instrumentation on day 1, then infusion of endotoxin (25 mcg/kg E. coli lipopolysaccharide) on day 3. Group HE (n = 7) underwent instrumentation then hemorrhagic shock (mean arterial pressure = 40 mm Hg for 4 hours) on day 1, then infusion of endotoxin on day 3. Group H (n = 5) were instrumented and hemorrhaged on day 1, and underwent anesthesia only on Day 3. Between periods of anesthesia the animals were allowed food and water ad lib and systemic blood was sampled for culture every 12 hours. On day 5, the animals were euthanized prior to organ sampling for bacterial culture. One animal from group HE died during endotoxic shock on day 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effects of isothiocyanate alkyl chain-length on hamster liver cytochrome P-450 activity.

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is metabolized by various isozymes of cytochrome P-450 present in microsomes. In this study, we examined the effects of the isothiocyanate homologues, phenyl isothiocyanate (PITC), benzyl isothiocyanate (BITC), phenethyl isothiocyanate (PEITC) and phenylpropyl isothiocyanate (PPITC) on the mutagenicity and in vitro metabolism of NNK by Syrian golden hamster liver microsomes and on the in vitro microsomal metabolism of testosterone. Each isothiocyanate compound inhibited N-oxidation and alpha-hydroxylation reactions of NNK that, except for PITC, correlated with an inhibition of microsomal-mediated mutagenicity of NNK in Salmonella typhimurium TA1535. Each isothiocyanate also inhibited cytochrome P-450-mediated hydroxylation reactions of the metabolism of testosterone. In general, the inhibitory potency of the isothiocyanates corresponded with the length of the alkyl chain of the compound. Our data support the ability of isothiocyanates to inhibit the activity of a number of isozymes of cytochrome P-450.

Animals↗
PubMed1994

Comparison of balanol from Verticillium balanoides and ophiocordin from Cordyceps ophioglossoides.

Recently, we reported the isolation of the potent protein kinase C inhibitor balanol (1) from the fungus Verticillium balanoides. In an earlier study, König et al. reported the isolation of ophiocordin (3), a structural isomer of 1, from the fungus Cordyceps ophioglossoides. The present study was designed to clarify whether or not balanol and ophiocordin are different compounds. The results indicated that the two fungi produced the same compound, the structure being that assigned to balanol. In addition, a thirty-fold increase in the production of balanol from V. balanoides was observed when the culture medium was changed from cornmeal/tomato paste to soy meal/glycerol.

Antifungal Agents↗
PubMed1993

Effects of capsaicin on liver microsomal metabolism of the tobacco-specific nitrosamine NNK.

Chemically-induced mutagenesis and carcinogenesis is modulated by various plant products, some of which are present in the human diet. 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent carcinogen in tobacco and tobacco smoke, is activated by microsomal enzymes. In this study, we investigated the effects of capsaicin on the in vitro metabolism of NNK. Capsaicin is the principal component of Capsicum fruits used widely by humans as a food additive. Liver microsomes from saline-injected, phenobarbital-induced and beta-naphthoflavone-induced hamsters were used. Microsomes from phenobarbital and beta-naphthoflavone-induced animals expressed decreased NNK reduction and enhanced pyridine-N-oxidation, but did not significantly alter alpha-carbon hydroxylation of NNK. Capsaicin (0.5 mM) inhibited the formation of all metabolites of NNK by all microsomal fractions and inhibited alpha-hydroxylation by phenobarbital-induced microsomes more than by either of the other two treatments. Our results suggest that capsaicin, as a naturally occurring dietary constituent, possesses antimutagenic and anticarcinogenic properties through the inhibition of xenobiotic metabolizing enzymes.

Animals↗
PubMed1993

The use of blood in resuscitation of the trauma patient.

The ability to transfuse blood (a form of tissue transplantation) with relatively few immediate and long-term complications has led to increased survival in victims of injury who require massive amounts of blood. The primary deficit in hypovolemic shock secondary to trauma is in oxygen transport to the hypoperfused tissues; therefore, blood transfusion has an essential role in therapy during resuscitation and definitive treatment. The major immediate complications to be avoided are hypothermia and acidosis, which are the main causes of the coagulopathy associated with massive transfusion. The most worrisome long-term complication is the transmission of disease, of which hepatitis C is the most frequent. With improved screening techniques and heightened donor awareness, the risk of disease transmission is less than 2%. Until synthetic oxygen-carrying solutions are available, the transfusion of red blood cells, when appropriately indicated, will remain an important component in the resuscitation of the trauma patient.

Acquired Immunodeficiency Syndrome↗
PubMed1992

The effects of ischemia and ischemia-reperfusion on bacterial translocation, lipid peroxidation, and gut histology: studies on hemorrhagic shock in pigs.

The bacterial translocation hypothesis was tested in two studies (acute and subacute) in a porcine model of hemorrhagic shock. Male pigs (30-40 kg each) under general anesthesia had their femoral vein, femoral artery, and portal vein catheterized. After stabilization (1 hour) they were bled (40% of blood volume) over 30 minutes, then maintained in the hypotensive state (MAP = 30-40 mm Hg) for 2 hours, following which, according to randomization, they entered the control group or were resuscitated with whole blood (WB group) or with lactated Ringer's solution (LR group). In the acute study, the mesenteric efferent lymphatic was also cannulated, the control group was not resuscitated, and the animals remained under general anesthesia to the end of the experiment (8.5 hours), when gut tissue was obtained for histologic study and measurement of lipid peroxidation. In the subacute study, the control group was not bled, the animals were awakened at 6.5 hours, and the portal vein catheter remained in situ until 48 hours. In both studies, samples of portal blood were obtained for culture at regular intervals and on completion, samples from mesenteric lymph nodes (MLNs) for culture were taken in the acute study, and in the subacute study samples from MLNs, spleen, and liver were obtained. In the acute study significant bacterial translocation to the MLNs and portal blood did not occur among the controls (n = 3), the LR group (n = 5), and the WB group (n = 6). Significant evidence of lipid peroxidation was found in both the LR and WB groups. Histologic assessment showed no difference among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Hemorrhagic shock and bacterial translocation in a swine model.

Bacterial translocation is proposed as an explanation for sepsis associated with hemorrhagic shock. This study attempted to document these events in a large animal model. Male swine were randomly assigned to control (n = 10) or experimental (n = 10) groups. Animals were anaesthetized, and the bladder, portal vein, and a mesenteric lymphatic vessel cannulated. Experimental animals were bled 40% of blood volume. Over the next six hours maintenance fluids were given, and cultures of portal blood and mesenteric lymph taken. Before the swine were killed, cultures were taken from portal and systemic blood, mesenteric lymph, and lymph nodes, and a portion of terminal ileum was resected for histologic study. Experimental animals experienced significant shock as demonstrated by changes in hemodynamic and biochemical variables. Cultures and histologic examination of the terminal ileum showed no significant difference between control and experimental animals. In an unresuscitated swine model, significant bacterial translocation was not demonstrated within six hours of hemorrhagic shock.

Animals↗
PubMed1991

Coalition on trauma--trauma prevention and trauma care: presidential address, Trauma Association of Canada.

Injury is the leading cause of death in persons under 40 years of age. The cost to society financially and in nonmonetary terms is enormous. For a successful assault on this major health epidemic, a cooperative effort between those involved in the development of prevention strategies and those involved in the care of the injured patient must develop. For our society to accept some of these prevention strategies, the rights of the community as a whole will have to be allowed to prevail over the rights of the individual. To facilitate this process, a National Advisory Committee on Injury in Canada needs to be formed. Its mandate will be to develop a set of national objectives on injury morbidity and mortality, to establish a national trauma registry, and to implement specific programs--a strategic plan. Only through a coalition of efforts between all groups involved with injury can we hope to lower the prevalence of injury in Canada.

Accidents, Traffic↗
PubMed1990

Predictive equation for assessing energy expenditure in mechanically ventilated critically ill patients.

Traditional formulas, such as the Harris and Benedict equation (HBE), do not accurately predict energy expenditure (EE) in mechanically ventilated, critically ill patients (MVCIP). The purpose of this study was to develop a predictive EE equation to assess EE requirements in MVCIP. A portable metabolic cart was used to measure indirectly EE in 112 MVCIP. Patients were studied at rest and for 30 min on the first or second day of ICU admission. No nutrition was received during the study period. Variables investigated were: age, BSA, Acute Physiology and Chronic Health Evaluation (APACHE II) score, sepsis score, Injury Severity Score (ISS), respiratory rate (f), tidal volume (VT), minute ventilation, mean arterial pressure, heart rate, body temperature (Temp), and outcome. Patient age, APACHE II score, sepsis score, ISS, and BSA were 50 +/- 20 yr, 16 +/- 7, 11 +/- 6, 32 +/- 14, and 1.80 +/- 0.27 m2, respectively. Correlation and multiple regression analyses were used with EE as the dependent variable. A predictive equation (EE [kcal/day] = 945 BSA -6.4 age + 108 Temp + 24.2 f + 817 VT -4349) was determined from variables that contributed greater than 3% to the variance of EE: BSA (52%), age (10%), f (5%), VT (5%), and Temp (3%). The HBE underestimated measured EE by 34 +/- 19% and in 79 patients deviated greater than 15%. Using the new equation, only 15 patients' EE deviated greater than 15% from measured EE. The new predictive EE equation can accurately assess EE in MVCIP.

Adult↗