Biomedical subjects

W W LaMorte

Publications and source records attributed to W W LaMorte.

At least 19 recordsLinked to original sources

PubMed2000

Role of stasis and oxidative stress in ileal pouch inflammation.

BACKGROUND: Although ileal pouch-anal anastomosis has become the operation of choice for patients with chronic ulcerative colitis and familial adenomatous polyposis coli, ileal pouch inflammation or pouchitis remains a significant postoperative complication. Numerous factors such as fecal stasis have been implicated in the etiology of pouchitis; however, pouchitis remains poorly understood due to the lack of a small animal model. One of the primary goals of this study was to surgically create a reservoir or U-pouch in the ileum of a rat in which stasis would occur in a manner that was unimpeded by other complicating factors such as a colectomy. This model would allow investigation of the hypothesis that intestinal stasis leads to biochemical changes that predispose the ileal pouch to inflammation and oxidative stress. MATERIALS AND METHODS: A U-pouch was surgically created in the terminal ileum of Lewis rats just proximal to the ileocecal valve without a colectomy. Stasis was assessed by serial barium radiographs over 48 h. Thirty days after surgery, mucosa was obtained from the ileal U-pouches and nonoperated ileum to assess inflammation and neutrophil infiltration histologically and by measuring myeloperoxidase activity. Oxidative stress was assessed by measuring 8-isoprostane levels in urine. Once the model was validated and it was established that stasis and inflammation occurred in the pouch, either vitamin E or allopurinol was administered for 30 days after which myeloperoxidase and 8-isoprostane levels were again measured. RESULTS: In our experimental model, ileal stasis resulted in increases in both mucosal myeloperoxidase activity and urinary 8-isoprostane levels, suggesting that oxidative stress was associated with stasis. Thirty-day treatment with vitamin E or allopurinol reduced ileal myeloperoxidase activity and urinary 8-isoprostane levels. CONCLUSION: These studies demonstrated that stasis in the ileum occurred and was associated with neutrophil infiltration and oxidative stress. Antioxidant treatment reduced the inflammatory response suggesting a role for antioxidant therapy in the treatment of pouchitis.

Animals↗

PubMed1998

Determinants of the selection of phosphatidylcholine molecular species for secretion into bile in the rat.

Certain phosphatidylcholine (PC) molecular species appear to be secreted into bile preferentially, but the mechanism for this selection remains obscure. We used multivariate analysis to examine the relationship between PC structure and the odds of secretion for individual PC species secreted into bile. PC was isolated from Folch extracts of bile and liver from rats, and individual molecular species of PC were quantified with reverse-phase high-performance liquid chromatography (HPLC). The odds of secretion for a given PC species were quantified as the ratio of its mole% in bile/mole% in liver. Regression analysis indicated that the odds of secretion were significantly related to length of both the sn-1 and sn-2 acyl chains (P < .0001 for both) and to relative hydrophobicity as determined by reverse-phase HPLC (P < .0001). In addition, the relationship between odds of secretion and sn-1 chain length was best described by a parabolic function. Considered together, these characteristics accounted for 88% of the observed differences in odds of secretion. This relationship between PC structure and odds of secretion was strikingly similar to the relationship between PC structure and affinity for bovine PC transfer protein. When multivariate models were used to predict both the odds of secretion and the affinity for PC transfer protein for a set of biologically plausible PC species, there was a linear relationship between the two. The likelihood of a given PC species being secreted into bile can be related to the structural characteristics of the acyl chains without having to postulate the existence of a special pool of PC destined for biliary secretion. Second, the structural characteristics that dictate selection of PC species for secretion into bile are similar to those that determine binding affinity for PC transfer protein, suggesting that the likelihood of a PC being secreted into bile is, in fact, closely related to its binding affinity for PC transfer protein (PC-TP).

Androgen-Binding Protein↗

PubMed1998

Is splenectomy more dangerous for massive spleens?

BACKGROUND: Reports vary about whether risks are greater for removal of massive (> or = 1500 g) spleens than for smaller (< 1500 g) spleens. We sought to determine the hazards of splenectomy. METHODS: We reviewed 223 consecutive adults with elective splenectomies for hematologic diseases. Morbidity and mortality rates were combined with published data to create a meta-analysis. RESULTS: Patients with massive spleens are more likely to have postoperative complications (relative risk [RR] 2.1, 95% confidence interval [CI] 1.3 to 3.4; P = 0.003) and death (RR 4.7, 95% CI, 1.5 to 15.1; P = 0.01). However, when the investigation is restricted to comparable diagnoses, patients with massive spleens do not differ from those with smaller spleens regarding complications (RR 1.4, 95% CI, 0.8 to 2.7; P = 0.3) or mortality (RR 2.1, 95% CI, 0.5 to 9.7; P = 0.4). These observations are confirmed by metaanalysis. Furthermore, multivariate analysis indicts age as a critical risk of complications and death. CONCLUSIONS: Increased age and underlying illness are the predominant factors associated with morbidity and mortality following splenectomy for hematologic disease. Adjusting for age and diagnosis, spleen size is not a hazard.

Age Factors↗

PubMed1998

Impact of a critical pathway on postoperative length of stay and outcomes after infrainguinal bypass.

PURPOSE: To determine the effect of a critical pathway on postoperative length of stay and outcomes after infrainguinal bypass. METHODS: A critical pathway for care of patients after infrainguinal bypass was introduced in December 1995 to coordinate postoperative care at our institution. We compared care of 67 consecutively treated patients before institution of the pathway with care of 69 consecutively treated patients with the critical pathway in place. Data collection was done by means of chart review. Univariate analyses were used to identify differences between prepathway and postpathway patients and to identify factors influencing postoperative length of stay. Multivariate analysis was used to identify factors that influenced length of stay and to examine the effect of use of the pathway after adjusting for other factors. RESULTS: Patients on the pathway were similar to prepathway controls with respect to comorbid illnesses, vascular risk factors, indications for surgical treatment, type of conduit, and type of operation. Factors associated with longer postoperative stays included distal anastomoses to tibial rather than popliteal vessels (p = 0.02), preexisting cardiac disease (p = 0.005), postoperative complications (p = 0.0003), lower preoperative hematocrit (p = 0.01), and elevated preoperative creatinine level (p = 0.006). Overall, pathway patients had somewhat shorter postoperative lengths of stay (median value 7 days; range 2 to 29 days) than prepathway patients (median value 6 days; range 2 to 35; p = 0.01), and the two groups had similar frequencies of postoperative complications, readmission, and 6-month mortality. However, patients on the pathway were more likely to be discharged to an intermediate-care facility rather than directly home. After 12 patients with extraordinarily prolonged postoperative stays were excluded, multivariate analysis indicated that pathway patients had significantly shorter postoperative stays (p = 0.001). However, the difference was not significant if patients with extraordinarily long postoperative stays were included in the analysis (p = 0.28). CONCLUSION: Use of a critical pathway was associated with a modest decrease in postoperative length of stay for most patients. This was accomplished without an adverse effect on readmission, complication, or mortality rates. However, the decrease in stay may have been achieved primarily by discharging more patients to intermediate-care facilities. The pathway did not appear to have any effect when the subset of patients with extraordinarily long stays because of complex medical problems was included.

Aged↗

PubMed1997

Effects of dietary cholesterol and triglycerides on lipid concentrations in liver, plasma, and bile.

Dietary cholesterol (CHL) and triglycerides (TG) can influence plasma, hepatic, and biliary lipid composition, but effects on lipids in these three compartments during the early stages of CHL gallstone formation have not been studied in parallel. We fed prairie dogs diets containing one of four test oils (safflower, coconut, olive, or menhaden) at either 5 or 40% of calories, in the presence of 0 or 0.34% CHL, for 3 wk. In the absence of dietary CHL, increases in dietary TG produced 50-200% increases in the concentrations of biliary CHL and hepatic cholesteryl ester (CE), while the concentrations of hepatic free CHL (FC) as well as plasma FC and CE remained relatively unchanged. Increasing dietary CHL to 0.34% resulted in increases in hepatic FC of approximately 50% for all four fats regardless of whether they were supplied at 5 or 40% of calories. CHL supplementation caused more pronounced increases in biliary CHL (200-400%), hepatic CE (50-200%), plasma FC (up to 100%), and plasma CE (up to 150%), and these increases were exacerbated by concurrent supplementation of dietary fat and CHL (biliary CHL: 300-700%; hepatic CE: 100-250%; plasma FC: up to 165%; plasma CE: 100-350%). These results indicate that enhanced secretion of biliary CHL and, to a lesser extent, increased synthesis of hepatic CE, may be primary mechanisms for maintaining the hepatic FC pool. Furthermore, dietary CHL and high levels of fat intake are independent risk factors for increasing biliary CHL concentrations, and adverse effects on lipid concentrations in plasma and bile tend to be exacerbated by ingestion of diets rich in both fat and CHL.

Animals↗

PubMed1996

Relationship of cardiovascular risk factors to racial differences in femoral bypass surgery and abdominal aortic aneurysmectomy in Massachusetts.

UNLABELLED: Atherosclerosis is more severe in blacks than in whites, but abdominal aortic aneurysms, which have traditionally been thought to have an atherosclerotic etiology, appear to be less common in blacks. Because of this incongruity, we compared risk factor profiles in patients undergoing abdominal aortic aneurysm repair and patients undergoing femoral bypass for atherosclerotic occlusive disease. A dual case-control study was conducted, first, comparing patients who had undergone aneurysmectomy to a control group of patients who had undergone appendectomy; and then comparing patients who had undergone femoral bypass surgery to the same appendectomy controls. We initially used hospital discharge data for the entire state of Massachusetts and, in a second phase, data obtained from a review of medical records from Boston University Medical Center Hospital and Boston City Hospital. The statewide database indicated that rates of femoral bypass surgery were higher in blacks than in whites, but after adjusting for differences in hypertension, diabetes, and low socioeconomic status, the black/white odds ratio for femoral bypass fell to 1.44 (95% confidence interval: 1.08, 1.92). A similar analysis based on the hospital chart review, provided better control of confounding and indicated that there was no racial difference in rates of femoral bypass after correcting for other risk factors (odds ratio = 0.94; 95% confidence interval: 0.40, 2.22; p = 0.90). In contrast, the statewide database found higher rates of abdominal aortic aneurysm surgery in whites, and particularly in white males. Smoking and hypertension were strong risk factors for aneurysmectomy, but diabetes mellitus and socioeconomic status were not. After adjusting for other variables, the black/white odds ratio for aneurysmectomy was 0.29 (95% confidence interval: 0.07, 1.23; p = 0.09). CONCLUSIONS: Substantial differences are found in the risk factor profiles for aneurysmal disease and femoral atherosclerotic occlusive disease. Diabetes is a particularly strong risk factor for femoral disease, but not for aneurysmal disease. In addition, blacks had higher rates of femoral bypass surgery in Massachusetts, but the apparent racial difference appeared to be due to a greater prevalence of hypertension, smoking, and diabetes in blacks. In contrast, abdominal aortic aneurysms occurred predominantly in white males, and adjustment for other risk factors further accentuated the greater risk in whites.

Adult↗

PubMed1996

Risks of synchronous gastrointestinal or biliary surgery with splenectomy for hematologic disease.

BACKGROUND: The addition of splenectomy to a gastrointestinal (GI) operation may have an adverse effect on mortality, morbidity, and even survival. OBJECTIVE: To determine the risks of the converse: synchronous GI surgery appended to splenectomy for hematologic diseases. DESIGN: Retrospective cohort. SETTING: Multiple hospitals comprising an affiliated surgical training program. PATIENTS: Consecutive sample of 207 adults (mean age, 49 years) with splenectomies for hematologic diseases. INTERVENTION: Splenectomy and concomitant GI or biliary surgery (group 1, n=19) and splenectomy alone (group 2, n=188). MAIN OUTCOME MEASURES: Length of hospital or intensive care unit stay, later operations, postoperative infections, postoperative abdominal abscess, major complications, and death. RESULTS: Preoperative and intraoperative factors were similar in both groups. Operative mortality was 3 of 19 in group 1 and 8 of 188 in group 2 (p=.07). The mean number of major complications tended to be higher in group 1 (1.5 vs 0.5, P=07). Despite no difference between the incidences of overall postoperative infections, patients in group 1 were much more likely to develop an abdominal abscess (4 of 19 vs 3 of 188, P=.002). Logistic regression established that patients undergoing splenectomy and synchronous GI or biliary surgery were 25 times more likely to develop an intra-abdominal abscess than were patients with splenectomy alone, even controlling for confounding factors (odds ratio, 24.7; 95% confidence interval, 3.1 to 196; P=.002). CONCLUSIONS: Synchronous GI or biliary surgery with splenectomy for hematologic disease increases the risk of intra-abdominal abscess and should be avoided. Complication and mortality rates may also be increased.

Abdominal Abscess↗

PubMed1996

The influence of wound geometry on the measurement of wound healing rates in clinical trials.

PURPOSE: The comparison of wound healing rates in clinical trials presents a challenging problem. Wound healing typically has been expressed as a change in area over time or a percent change in area over time. These methods are inaccurate, however, when applied to wounds of varying size and shape. A relatively small amount of healing in a large wound will produce a greater change in area than in a smaller wound. Conversely, measurement of the percent change in area of a wound will tend to exaggerate the healing rates of smaller wounds. A method of calculating average linear healing of the wound edge toward the center of the wound has been proposed that should not be influenced by wound size: D = delatA divided by P, where D = linear healing, deltaA = change in area, and P = mean perimeter. The purpose of this study was to examine linear healing of the wound edge as a method of measuring wound healing in clinical trials. METHODS: We observed 39 patients with venous stasis ulcers. The area, perimeter, length, and width of each wound were calculated with computerized planimetry. Change in area per day and linear healing rate of the wound edge per day were calculated. Multiple linear regression analysis was used to explore factors that influence wound healing as measured by these methods. RESULTS: The change in area per day was significantly and independently influenced by initial area (p < .0001), perimeter (p < .0001), length (p < .00055), and width (p < .0175). Linear healing per day was not influenced by any geometric variable, including area, perimeter, length, width, and ratio of width to length. CONCLUSION: Linear healing per day is a valid means of comparing wound healing rates in wounds of different dimensions. Linear healing per unit of time should be preferred to measurements of change in wound area to quantify wound healing rates in clinical trials.

Chronic Disease↗

PubMed1995

Predictive accuracy of the TRISS survival statistic is improved by a modification that includes admission pH.

OBJECTIVE: To determine if pH measured at the time of hospital admission and corrected for PCO2 was an independent predictor of trauma survival. DESIGN: Phase 1 was a retrospective case-control analysis of 1708 patients, followed by multivariate multiple logistic regression analysis of a subset of 919 patients for whom the Revised Trauma Score (RTS), Injury Severity Score (ISS), and pH were available. Phase 2 was a prospective comparison of a mathematical model of survival derived in phase 1 (pH-TRISS) with the TRISS method in 508 of 1325 subsequently admitted trauma patients. SETTING: Urban level 1 trauma center. PATIENTS: All patients admitted with blunt or penetrating trauma during the study period. MAIN OUTCOME MEASURES: Survival vs mortality. RESULTS: In phase 1, factors significantly associated with mortality by t test and chi 2 analysis included the RTS, ISS< Glasgow Coma Scale, corrected pH (CpH), and sum of the head, chest, and abdominal components of the Abbreviated Injury Scale-85 (AIS85) (HCAISS) (for all, P < .0001). The TRISS statistic was also a significant predictor of survival (P < .004). Age, sex, and the extremity and soft tissue components of the AIS85 were not associated with mortality. In a multivariate analysis of the RTS, HCAISS, and CpH, all were significant predictors of mortality. Even when controlling for RTS and HCAISS, CpH remained a significant predictor of mortality (P < .008). In phase 2, when pH-TRISS was tested prospectively against TRISS in a new group of patients, the new statistic appeared to provide a more accurate prediction of survival. CONCLUSIONS: The arterial pH measurement obtained on hospital arrival and corrected for PCO2 is a significant independent predictor of survival and adds to the predictive accuracy of the TRISS survival statistic. Age, sex, and the extremity and soft tissue components of the AIS85 did not contribute to the accuracy of the TRISS statistic in this patient population.

Abbreviated Injury Scale↗

PubMed1995

Prevention of renal cortical ischemia during aortic clamping with prostaglandin E1.

OBJECTIVES: To investigate the effects of aortic clamping and prostaglandin E1 on systemic hemodynamics and renal cortical and medullary blood flow by means of continuous intraparenchymal laser Doppler fluorometry. DESIGN: Experimental animal study in a porcine model. With the animal under general anesthesia after hemodynamic monitoring was instituted, surgical exposure was obtained through a small left retroperitoneal incision. The kidney was left undisturbed. Intraparenchymal laser Doppler probes (0.44 mm in diameter) were inserted in the renal cortex and medulla. In the first group of six animals, systemic hemodynamic variables, urine output and renal cortical and medullary flow were measured at baseline after 60 minutes of equilibration, and after 15 minutes of aortic clamping and unclamping. Data are given as mean +/- SE. INTERVENTION: In another six animals, prostaglandin E1 (20-micrograms intravenous bolus given over 1 minute) was given before clamping, and the same variables were recorded. RESULTS: In the first group, aortic clamping caused no change in cardiac output or filling pressures. Cortical blood flow decreased from 40.4 +/- 3.7 to 33.3 +/- 2.7 mL/100 g per minute (P < .0004) after clamping, and to 27 +/- 2.3 mL/100 g per minute (P < .0001) after unclamping, and was associated with a decrease in urine output from 3.2 +/- 0.5 to 2 +/- 0.2 mL/min (P < .0013). Medullary flow remained the same at 9.2 +/- 0.8, 10 +/- 0.3, and 9.8 +/- 0.6 mL/100 g per minute, respectively. These adverse effects were prevented when prostaglandin E1 was given before clamping. There was an initial drop in blood pressure (100 +/- 4 to 89 +/- 5 mm Hg, P < .0004), but cardiac output (43.3 +/- 5.8 L/min) and filling pressures (6 +/- 1 mm Hg) were unchanged. Cortical flow was preserved during the entire period of clamping and unclamping (43.3 +/- 5.8 mL/100 g per minute). Medullary flow remained unchanged (10 +/- 0.8 mL/100 g per minute). Urine output increased from 2 +/- 0.3 to 3.4 +/- 0.6 mL/min (P < .006). CONCLUSIONS: In this animal model, infrarenal aortic clamping causes a significant decrease in renal cortical flow and urine output with no significant changes in filling pressures, cardiac output, or medullary blood flow. These adverse effects are prevented by pretreatment with prostaglandin E1, which prevents cortical ischemia and maintains brisk diuresis.

Alprostadil↗

PubMed1995

Comparison of skeletal muscle laser Doppler flowmetry to changes in central hemodynamics in detecting the physiological response to moderate hemorrhage.

Previous studies have demonstrated that laser Doppler (LD) flowmetry is a useful technique for following changes in blood flow in a tissue bed, but the potential role of LD flowmetry in management of the critically ill patient is unclear. This study sought to establish the sensitivity of LD flowmetry compared to changes in centrally measured hemodynamic parameters in response to a mild hemorrhagic episode. In order to establish the correlation between LD flow and actual blood flow, livers from Sprague-Dawley rats were isolated and perfused via the portal vein with citrate anti-coagulated rat blood. Changes in LD flow were recorded while changing blood flow via the perfusion pump. There was a strong correlation between pump flow and LD flow (for N = 5 livers, r > 0.9; P < 0.05). This relationship was stable at hematocrits > 20. The second part of this study tested the sensitivity of LD flowmetry in anesthesized baboons. An LD probe was placed on the surface of the gracilis muscle of the adult male baboons. LD flow and hemodynamic parameters were measured following two episodes of bleeding and reinfusing 250 cc of blood. During the first bleed there were significant changes in heart rate (97 + 8 to 159 + 12), mean arterial pressure (125 + 6 to 105 + 9), and LD flow (20.6 + 4.6 to 11.9 + 3.6); these parameters returned to normal after reinfusion of blood. During the second bleed, the only parameters that showed significant changes were heart rate (118 + 5 to 135 + 12) and LD flow (17.5 + 8 to 10.7 + 3.4).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Characteristics of patients at risk for perioperative myocardial infarction after infrainguinal bypass surgery: an exploratory study.

Patients requiring infrainguinal bypass surgery often have diffuse atherosclerotic disease, and perioperative myocardial infarction (MI) is a potentially lethal complication that is not uncommon in these patients. To establish additional clinical characteristics that might be useful in identifying patients who require more extensive cardiac evaluation, we conducted an exploratory case-control study comparing 22 patients who had a perioperative MI following elective infrainguinal bypass surgery with 191 control subjects whose bypasses were uneventful. In addition to previously recognized risk factors (e.g., history of angina or prior MI), we examined the association of perioperative MI with (1) results of common preoperative laboratory tests and ECG, (2) preoperative use of certain medications, and (3) intraoperative factors that might be anticipated prior to surgery (e.g., duration of surgery or type of anesthesia). Perioperative MI was associated not only with a history of angina, prior MI, or coronary artery disease but also with the need for certain cardiac medications, higher white blood cell (WBC) counts, ST-segment depression, left bundle branch block, and lengthy surgical procedures. Multiple logistic regression analysis identified the following factors as being independently associated with perioperative MI: preoperative antiarrhythmic agents (odds ratio [OR] = 26.4, p = 0.006), nitrates (OR = 8.4, p = 0.006), calcium channel blockers (OR = 5.5, p = 0.04), and aspirin (OR = 6.8, p < 0.01) and ST-segment depression (OR = 11.8, p = 0.01), WBC count (OR = 1.27/1000, p = 0.005), and duration of surgery (OR = 2.2/hr, p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

Risk factors for chronic venous insufficiency: a dual case-control study.

PURPOSE: Most epidemiologic studies on chronic venous insufficiency (CVI) are cross-sectional surveys that suggest potential risk factors by describing their population. However, these relationships could be due to the CVI population's older age. We performed a dual case-control study with multivariate analysis to address this issue. METHODS: Ninety-three patients with venous ulcers, 129 patients with varicose veins (VV), and 113 general population control patients from two hospitals were interviewed by use of a standardized questionnaire covering medical history, patient demographics, medications, and lifestyle questions. Univariate and multivariate analyses were used to compare the groups. RESULTS: Univariate analyses showed CVI to be characterized by several factors, many of which were found to be age related after multivariate analysis. Age-adjusted relationships for CVI include male sex and obesity. Histories of serious leg injury or phlebitis were important associations resulting in a 2.4-fold and 25.7-fold increase in risk for CVI, respectively. After adjusting for age, subjects with VV tend to be younger and female, to more frequently have a history of phlebitis, and to report a family history of VV more frequently than control subjects. CONCLUSIONS: Many of the previously suggested associations found with CVI are in reality due to this population's greater age. Patients with CVI are older, male, obese, have a history of phlebitis, and have a history of serious leg injury. These results suggest that a prior deep vein thrombosis, either clinical or subclinical, may be a predisposing factor for CVI.

Age Distribution↗

PubMed1995

Racial differences in the incidence of femoral bypass and abdominal aortic aneurysmectomy in Massachusetts: relationship to cardiovascular risk factors.

PURPOSE: Atherosclerotic disease appears to be more severe in black patients than in white patients, but abdominal aortic aneurysms, which have traditionally been believed to have an atherosclerotic cause, are reported to be less common in black patients than in white patients. Our goals were to compare and contrast factors associated with the development of abdominal aortic aneurysms and clinically significant atherosclerotic occlusive disease (1) to determine whether these diseases share a common cause and (2) to explore their association with race. METHODS: Dual case-control studies were conducted with multivariate analysis to compare cases (patients undergoing aneurysmectomy or patients undergoing femoral bypass) with a comparison group consisting of patients who had undergone appendectomy. Two data sources were used: (1) hospital discharge data for Massachusetts from 1984 through 1988 and (2) medical records at University Hospital of Boston and Boston City Hospital. For both the Massachusetts database and the hospital chart review, records were obtained for all patients discharged between January 1984 and December 1988 with an International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) procedure code for abdominal aortic aneurysm resection (38.44) or aneurysmorrhaphy (38.34) or with a procedure code for femoral artery bypass/reconstruction (39.29). To conduct a nested case-control study, records were also obtained for a control group consisting of patients between the ages of 50 and 84 years who had undergone appendectomy during the same 5-year period. RESULTS: Black patients had higher rates of femoral bypass than did white patients after adjustment for age and sex (odds ratio = 1.97; 95% confidence interval: 1.49, 2.61; p < 0.0001). However, femoral bypass was also associated with hypertension, diabetes, and low household income. After adjusting for these additional factors in the statewide data set, the black/white odds ratio for femoral bypass was only 1.44 (95% confidence interval: 1.08, 1.92). The parallel case-control study at University Hospital and Boston City Hospital, which provided information about smoking status and more accurate ascertainment of coexisting hypertension and diabetes, indicated that there was no racial difference in rates of femoral bypass after correcting for these additional risk factors (odds ratio = 0.94; 95% confidence interval: 0.40, 2.22; p = 0.90). In contrast, abdominal aortic aneurysmectomy occurred predominantly in white men. Aneurysmectomy was also associated with smoking and hypertension, but aneurysmectomy was not significantly associated with diabetes mellitus or family income. The black/white odds ratio for aneurysm was 0.29; (95% confidence interval: 0.07, 1.23; p = 0.09 after adjustment for other variables). CONCLUSIONS: Hypertension, smoking, and male sex are risk factors for the development of femoral atherosclerosis and abdominal aortic aneurysm formation. However, abdominal aortic aneurysms occur predominantly in white men and do not appear to be associated with diabetes mellitus or income. In contrast, the higher rate of femoral artery bypass in black patients is probably the result of greater prevalence among black patients of hypertension, diabetes, smoking, and perhaps by other ill-defined factors associated with socioeconomic status.

Age Distribution↗

PubMed1994

Biliary phospholipases in the prairie dog model for cholesterol cholelithiasis.

Lysolecithin has been implicated as a contributing factor in the pathogenesis of cholecystitis and cholesterol cholelithiasis. The phospholipases are key enzymes in the generation of a number of metabolites including lysolecithin, but conflicting reports exist concerning the presence of these enzymes in the biliary tract. In this study, measurement of phosphatidylcholine-specific phospholipase activity by means of the hydrolysis of radiolabeled phosphatidylcholine (100 nmol) by 90 micrograms of homogenate protein during a 60-min incubation demonstrated substantial enzyme activities in gastric fundus and distal ileum (90% and 70% hydrolysis, respectively), whereas activity was virtually undetectable in gallbladder mucosa (0.7% hydrolysis). Additional studies were conducted in prairie dogs fed diets high in cholesterol or with trace amounts of cholesterol using homogenates of gallbladder mucosa, seromuscularis and full-thickness tissue, as well as samples of hepatic and gallbladder bile. The only hydrolytic activity in excess of blank values that was detected was a highly variable phospholipase A2 activity in several gallbladder biles from animals given diets with both low levels and high levels of cholesterol, with the enzyme activities of the two dietary groups being similar. These results demonstrate that prairie dog gallbladder contains extremely low levels of phospholipase activity, in marked contrast to other gastrointestinal tissues. However, there was evidence of a phospholipase A2 activity in gallbladder bile. In light of the low activity in gallbladder tissue, the source of this enzyme appears to be the liver and not the gallbladder.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Transanal intracolonic pulse oximetry as a means of monitoring the adequacy of colonic perfusion.

Techniques for determining intraoperative compromise in colonic blood flow during aortic reconstruction are inadequate. We investigated the use of transanally recorded oxygen saturation in a porcine model. A Nellcor RS-10 reflectance pulse oximeter probe was attached to the balloon of a Foley catheter and passed transanally to record the oxygen saturation of the sigmoid colonic mucosa. The blood flow rate of the caudal mesenteric artery (CMA) was recorded with a Transonic ultrasonic flowmeter. CMA flow and transanal O2 saturation were recorded simultaneously as CMA flow was progressively decreased by compression of the infrarenal aorta. With unimpeded blood flow the mean O2 saturation in the distal colonic mucosa was 92.9% +/- 2.8. As CMA flow was progressively decreased to 20% of baseline flow, there was a linear decrease in colonic O2 saturation (r = 0.91 P < 0.01). At 20% of basal CMA flow, colonic O2 saturation was 54.0% +/- 4.1. Below 20% of basal CMA flow there was an abrupt loss of signal from the pulse oximeter. This study suggests that transanal pulse oximetry would provide a simple means of continuously monitoring the adequacy of distal colonic blood flow intraoperatively and may prove to be useful during aortic reconstruction when there is concern about the adequacy of blood flow to the distal colon.

Anal Canal↗

PubMed1993

Changes in hepatocyte NADH fluorescence during prolonged hypoxia.

Deprivation of oxygen reduces oxidative phosphorylation and rapidly causes an increase in cellular NADH which can be monitored by fluorimetry. Previous studies have established that increases in NADH fluorescence accurately reflect the impairment in oxidative phosphorylation which occurs during brief periods of acute hypoxia. However, the potential usefulness of fluorimetry for following longer, clinically relevant periods of ischemia has not been explored. We studied changes in NADH fluorescence in rat hepatocyte suspensions and in isolated-buffer-perfused rat livers during hypoxia (pO2 < 50 mm Hg) for periods as long as 180 min. NADH fluorescence of hepatocyte suspensions consistently increased by about 15% after 13 to 15 min of hypoxia and coincided with a marked decrease in tissue ATP levels. Reoxygenation after 15 or 30 min of hypoxia resulted in recovery of ATP and NADH with minimal loss of viability, as measured by trypan blue exclusion. After 60 to 180 min hypoxia, the initial increase in NADH fluorescence was followed by a progressive, irreversible decline which correlated with decreased cell viability. Similar changes in NADH fluorescence were observed in isolated-perfused rat livers in which NADH fluorescence was monitored at the liver surface with a fiberoptic probe. Hypoxia for 30 min had no effect on NADH fluorescence, but hypoxia for longer periods caused a steady increase in fluorescence after 45-60 min. When hypoxia was prolonged (120 or 180 min), fluorescence peaked after 60-75 min and then declined progressively to levels below baseline. The greatest decrease in fluorescence was seen after 180 min of hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Increased dietary fat content accelerates cholesterol gallstone formation in the cholesterol-fed prairie dog.

Epidemiological studies have provided conflicting information about the relationship between fat consumption and gallstone formation. We studied cholesterol gallstone formation in prairie dogs after 1 wk of the following diets: (group A) a control diet with no added cholesterol and 5% of calories from corn oil, (group B) 1.2% cholesterol with 5% of calories from corn oil or (group C) 1.2% cholesterol with 40% of calories from corn oil. In controls serum cholesterol was 58.9 +/- 4.5 mg/dl, gallbladder bile was unsaturated with cholesterol (cholesterol saturation index = 0.7 +/- 0.1; cholesterol = 3.8 mmol/L) and none of 12 animals formed cholesterol crystals or stones. The low-fat diet supplemented with cholesterol (group B) increased serum and biliary cholesterol concentrations to 292 +/- 76 mg/dl and 7.5 +/- 1.1 mmol/L, respectively (p < 0.05), but cholesterol saturation index was only modestly increased (1.1 +/- 0.1) and in only one of eight animals did cholesterol monohydrate crystals develop. Group C, animals, which received cholesterol plus high levels of corn oil, had higher serum cholesterol levels (457 +/- 66 mg/dl), higher biliary cholesterol concentrations (16.6 +/- 1.3 mmol/L), higher cholesterol saturation indexes (1.7 +/- 0.1) and increased incidence of cholesterol gallstones (5 of 11). The two cholesterol-supplemented diets increased biliary phospholipid concentrations, decreased the ratio of cholic/chenodeoxycholic acid and increased the proportion of biliary lecithins containing linoleic acid, but these abnormalities were greatest in group C, which was given large amounts of corn oil. These findings suggest that cholesterol gallstone formation in the prairie dog is accelerated by increased dietary omega-6 polyunsaturated triglycerides.

Animals↗