Heparin-induced thrombocytopenia: bovine versus porcine heparin in cardiopulmonary bypass surgery.

BACKGROUND: Studies have demonstrated a high incidence of antibodies to heparin/platelet factor 4 complexes, the antigen in heparin-induced thrombocytopenia, in patients after cardiopulmonary bypass surgery. In many hospitals, beef lung heparin has been used historically for cardiopulmonary bypass, and there has been reluctance to change to porcine heparin despite concerns of an increased incidence of heparin-induced thrombocytopenia in patients receiving bovine heparin. METHODS: A prospective randomized trial comparing bovine and porcine heparin in cardiopulmonary bypass surgery was conducted. Presurgery and postsurgery heparin antibody formation was studied using the serotonin release assay and a heparin/platelet factor 4 enzyme-linked immunosorbent assay. RESULTS: Data available on 98 patients, randomized to receive either bovine or porcine heparin, revealed no significant difference in patient positivity by serotonin release assay (12% in both groups) or by the heparin/platelet factor 4 enzyme-linked immunosorbent assay (29% with porcine and 35% with bovine heparin) postoperatively. There were no significant differences between preoperative and postoperative platelet counts or thromboembolic complications. CONCLUSIONS: Our study does not support the belief that bovine heparin is more likely than porcine heparin to induce the development of antibodies to heparin/platelet factor 4.

Improved sensitivity to insulin in obese subjects following weight loss is accompanied by reduced protein-tyrosine phosphatases in adipose tissue.

Insulin resistance in adipose tissue in human obesity is associated with increased protein-tyrosine phosphatase (PTPase) activity and elevated levels of the PTPases leukocyte common antigen-related PTPase (LAR) and PTP1B. To determine whether the improved insulin sensitivity associated with weight loss in obese subjects is accompanied by reversible changes in PTPases, we obtained subcutaneous adipose tissue from seven obese subjects (mean body mass index [BMI], 40.4 kg/m2) before and after a loss of 10% of body weight and again after a 4-week maintenance period. Weight loss was accompanied by an 18.5% decrease in overall adipose tissue PTPase activity (P = .015) that was further reduced to 22.3% of the control value (P = .005) at the end of the maintenance period. By immunoblot analysis, the abundance of LAR was decreased by 21% (P = .04) and abundance of PTP1B was decreased by 40% (P < .004) after the initial weight loss, and the decreases persisted during the maintenance period. Enhanced insulin sensitivity following weight loss, evident from a 26% decrease in fasting insulin levels (P < .05), was also closely correlated with the reduction in the abundance of both LAR (R2 = .80, P < .01) and PTP1B (R2 = .64, P = .03). These results support the hypothesis that LAR and PTP1B may be reversibly involved in the pathogenesis of insulin resistance, and may be therapeutic targets in insulin-resistant states.

The role of axillary dissection in mammographically detected carcinoma.

BACKGROUND: Axillary dissection remains a standard component of the treatment of invasive carcinoma of the breast. The presence of metastases to the regional lymph nodes guides adjuvant therapy and aids in determining prognosis. Mammography results in the discovery of small and often node-negative carcinomas of the breast. STUDY DESIGN: This 15-year, retrospective analysis investigated whether certain patients with small tumors could be spared the morbidity of axillary dissection. RESULTS: Medical records showed that from January 1980 to May 1995, 4,543 needle localization biopsies were done at York Hospital because of abnormalities detected on mammograms. Of these, 703 (15.5 percent) proved to be carcinoma. Of the carcinomas, 68 percent were infiltrating ductal carcinoma, 26 percent were ductal carcinoma in situ, and 5.4 percent were infiltrating lobular carcinoma. Axillary dissection was done on 588 patients, and 88.1 percent of the patients had no metastases to axillary lymph nodes. No axillary metastases were present in 109 patients with ductal carcinoma in situ who underwent axillary lymph node dissection or in 21 patients with microscopic invasive tumors. Only two of 54 patients with a T1a tumor (tumor [T], < or = 0.5 cm) had positive axillary nodes. Only one of 29 patients with a well-differentiated T1b tumor (T, > 0.5 to < or = 1 cm) had metastatic axillary nodes. In the presence of negative axillary lymph nodes, 19.2 percent of patients with a T1a tumor, 33.7 percent of patients with a T1b tumor, 60 percent of patients with a T1c tumor (T, > 1 to < or = 2 cm), and 78.9 percent of patients with a T2 tumor (T, > 2 cm) were given adjuvant chemotherapy or hormonal therapy. CONCLUSIONS: Patients with ductal carcinoma in situ and microscopic invasive tumors do not require node dissections. Possibly patients with T1a tumors and patients with well-differentiated, estrogen-receptor positive, progesterone-receptor positive, T1b tumors can also be spared axillary node dissection. By following this approach on occasion, patients with positive nodes might not undergo axillary lymph node dissection, but they may still be offered adjuvant therapy.

Prevalence of heparin-associated antibodies without thrombosis in patients undergoing cardiopulmonary bypass surgery.

BACKGROUND: Patients with cardiovascular disease almost invariably receive heparin before cardiopulmonary bypass surgery, which places them at risk of developing heparin-associated antibodies with a risk of thromboembolic complications. This study was designed to determine the prevalence of heparin-induced antibodies in patients before and after cardiopulmonary bypass surgery. METHODS AND RESULTS: Plasma from 111 patients was tested before surgery and 5 days after surgery for heparin-dependent platelet-reactive antibodies with a 14C-serotonin-release assay (SRA) and for antibodies to heparin/platelet factor 4 complexes with an ELISA. Heparin exposure after surgery was minimized. Heparin-dependent antibodies were detected before surgery in 5% of patients with SRA and 19% of patients with ELISA. By the fifth postoperative day, there was a marked increase in patients positive on the SRA or ELISA (13% and 51%, respectively; P < .01 for each). Patients who had received heparin therapy earlier in their hospitalization were more likely to have a positive ELISA before surgery (35%; P = .017) and a positive ELISA (68%; P = .054) or SRA (30%; P = .002) after surgery. However, there was no difference in the prevalence of thrombocytopenia or thromboembolic events between the antibody-positive and-negative groups. CONCLUSIONS: Approximately one fifth of patients undergoing cardiopulmonary bypass surgery have heparin-induced platelet antibodies detectable before the procedure as a result of prior heparin exposure, and many more develop antibodies after surgery. The absence of an association between these antibodies and thromboembolic complications in this study may be, in part, attributable to careful avoidance of heparin after surgery. The high prevalence of heparin-induced antibodies in this setting suggests that these patients may be at risk of developing thrombotic complications with additional heparin exposure.

Heparin and basic fibroblast growth factor are associated with preservation of latissimus cardiomyoplasties in goats: a retrospective study.

BACKGROUND: Chronic electrical stimulation of cardiomyoplasties often leads to atrophy and fibrosis of the skeletal muscle. In this retrospective study, we re-examined the data in our previous work, which suggested that muscle was preserved by treatment with basic fibroblast growth factor (bFGF). METHODS: Histologic sections were reviewed for evidence of atrophy, and fibrosis from four groups of goats with latissimus dorsi cardiomyoplasty: (1) unstimulated; (2) 2-Hz stimulated x 6 weeks; (3) 2-Hz stimulated with heparin infusion (50 units/hour) x 6 weeks; and (4) 2-Hz stimulated with bFGF (80-micrograms bolus/week) x 6 weeks. RESULTS: Muscle degeneration, as indicated by fat replacement of muscle fibers, was 56.95% +/- 9.16% (mean +/- S.E.) in the 2-Hz stimulated compared with 16.43% +/- 6.22% in unstimulated muscles. In 2-Hz = bFGF and 2 Hz-Heparin (Hep) groups, degeneration was 11.60% +/- 3.04% and 20.36% +/- 5.03%, respectively. bFGF treatment was associated with a greater latissimus blood flow than in the 2-Hz-untreated and 2 Hz-Hep groups (p < 0.05). CONCLUSIONS: bFGF's protection against degeneration may have involved angiogenesis and myogenesis, whereas that of heparin appears to have involved only myogenesis. While the mechanism(s) of the effects of heparin and bFGF remain to be defined, we conclude that they may be a useful adjunct for cardiomyoplasty.

Paracrine stimulation of preadipocyte-enriched cell cultures by mature adipocytes.

We developed a double-chamber system in which to examine the effects of mature adipocytes on the growth and differentiation of preadipocytes and other cells in the adipose tissue. In the present study we found that mature adipocytes from both lean and obese subjects release a factor that stimulates the growth of preadipocyte-enriched and dedifferentiated adipocyte-enriched cell cultures. This growth stimulation was dependent on both time of exposure to mature cells and the number of mature cells in the coculture. Proliferation of the preadipocyte-enriched (n = 4) and dedifferentiated adipocyte-enriched cultures (n = 5) in the presence of mature adipocytes from obese subjects [body mass index (BMI) > 35] was 4.1- and 2.9-fold more (P < 0.05) than that in the presence of adipocytes from lean subjects (BMI < or = 25). There was no difference in the growth of cultures enriched in preadipocytes or dedifferentiated adipocytes from lean or obese subjects in the absence of mature adipocytes. These observations demonstrate that mature adipocytes from obese patients stimulate the growth of preadipocyte-enriched cultures to a greater extent than those from lean individuals.

Mutation screening and identification of a sequence variation in the human ob gene coding region.

In the present study mRNA from the subcutaneous adipose tissue of 68 obese (defined as a body mass index > or = 27.3 for men and > or = 27.8 for women) and 38 lean subjects was screened for mutations in the ob gene coding region. No mutations in the coding region of the human ob gene were detected using Conformation Sensitive Gel Electrophoresis in 105 subjects. A first base substitution (G to A) was detected in one individual, which changed a valine to a methionine at position 94. The mRNA of all subjects contained the codon for glutamine-49, ruling out the possibility of a splice defect occurring during the removal of intron 2. These observations suggest that defects in the ob gene sequence itself are not the primary cause of obesity in humans.

Serum immunoreactive-leptin concentrations in normal-weight and obese humans.

BACKGROUND: Leptin, the product of the ob gene, is a hormone secreted by adipocytes. Animals with mutations in the ob gene are obese and lose weight when given leptin, but little is known about the physiologic actions of leptin in humans. METHODS: Using a newly developed radioimmunoassay, wer measured serum concentrations of leptin in 136 normal-weight subjects and 139 obese subjects (body-mass index, > or = 27.3 for men and > or = 27.8 for women; the body-mass index was defined as the weight in kilograms divided by the square of the height in meters). The measurements were repeated in seven obese subjects after weight loss and during maintenance of the lower weight. The ob messenger RNA (mRNA) content of adipocytes was determined in 27 normal-weight and 27 obese subjects. RESULTS: The mean (+/- SD) serum leptin concentrations were 31.3 +/- 24.1 ng per milliliter in the obese subjects and 7.5 +/- 9.3 ng per milliliter in the normal-weight subjects (P < 0.001). There was a strong positive correlation between serum leptin concentrations and the percentage of body fat (r = 0.85, P < 0.001). The ob mRNA content of adipocytes was about twice as high in the obese subjects as in the normal-weight subjects (P < 0.001) and was correlated with the percentage of body fat (r = 0.68, P < 0.001) in the 54 subjects in whom it was measured. In the seven obese subjects studied after weight loss, both serum leptin concentrations and ob mRNA content of adipocytes declined, but these measures increased again during the maintenance of the lower weight. CONCLUSIONS: Serum leptin concentrations are correlated with the percentage of body fat, suggesting that most obese persons are insensitive to endogenous leptin production.

The effect of basic fibroblast growth factor on the blood flow and morphologic features of a latissimus dorsi cardiomyoplasty.

Previous studies designed to determine whether latissimus cardiomyoplasty could be used to revascularize ischemic myocardium showed that after operation the latissimus was ischemic and had severely deteriorated. This study was undertaken to determine whether basic fibroblast growth factor, a potent angiogenic peptide, would improve the vascularity of the latissimus and enhance collateral formation between the muscle of the cardiomyoplasty and ischemic myocardium. In goats, myocardial ischemia was induced with an ameroid constrictor and cardiomyoplasty performed. The latissimus was continuously stimulated electrically at 2 Hz for 6 weeks and given four weekly bolus injections of human recombinant basic fibroblast growth factor (80 micrograms infused into the left subclavian artery). In eight animals, rates of regional blood flow were measured and both the heart and latissimus were evaluated histochemically. The latissimus blood flow rate was 0.114 +/- 0.029 ml/gm per minute, which was three times greater than that of historical controls (chronically stimulated latissimus cardiomyoplasty without basic fibroblast growth factor treatment; 0.042 +/- 0.007 ml/gm per minute, p < 0.05). Associated with the improved blood flow, there was significantly less evidence of skeletal muscle fiber dropout and muscle fibrosis in the animals treated with basic fibroblast growth factor. Latissimus-derived collateral flow to ischemic myocardium developed in five of the eight goats and averaged 0.288 +/- 0.075 ml/gm per minute. This flow was 42.8% +/- 15.7% (n = 5) of the flow required by normal myocardium (which was 0.728 +/- 0.095 ml/gm per minute). This value for latissimus-derived collateral blood flow was almost twice that of the historical controls (24.0% +/- 3.9%), but the increase did not achieve statistical significance (p = 0.08). These results hold the promise that basic fibroblast growth factor treatment might enhance the formation of extramyocardial collaterals to the heart and improve skeletal muscle function.

Evidence against either a premature stop codon or the absence of obese gene mRNA in human obesity.

Obese (ob) gene expression in abdominal subcutaneous adipocytes from lean and obese humans was examined. The full coding region of the ob gene was isolated from a human adipocyte cDNA library. Translation of the insert confirmed the reported amino acid sequence. There was no difference in the sequence of an reverse transcription PCR product of the coding region from five lean and five obese subjects. The nonsense mutation in the ob mouse which results in the conversion of arginine 105 to a stop codon was not present in human obesity. In all 10 human cDNAs, arginine 105 was encoded by CGG, consequently two nucleotide substitutions would be required to result in a stop codon. To compare the amount of ob gene expression in lean and obese individuals, radiolabed primer was used in the PCR reaction with beta-actin as a control. There was 72% more ob gene expression (P < 0.01) in eight obese subjects (body mass index, BMI = 42.8 +/- 2.7) compared to eight lean controls (BMI = 22.4 +/- 0.8). Regression analysis indicated a positive correlation between BMI and the amount of ob message (P < 0.005). There was no difference in the amount of beta-actin expression in the two groups. These results provide evidence that ob gene expression is increased in human obesity; furthermore, the mutations present in the mouse ob gene were not detected in the human mRNA population.

Five-year survival of 100 women with carcinoma of the breast diagnosed by screening mammography and needle-localization biopsy.

Carcinoma of the breast was studied in 100 women who underwent needle localization and open breast biopsy for lesions found by screening mammography from January 1980 to May 1987. The average age of the patients found to have carcinoma was 59.2 years, and 16 percent of patients were younger than 50 years of age. Pathologic examination revealed 62 patients with infiltrating ductal carcinoma, 31 patients with ductal carcinoma in situ, and seven patients with infiltrating lobular carcinoma. In 34 patients the carcinoma was microscopic. Thirty-six patients had carcinomas less than or equal to 1 centimeter, and 30 patients had carcinomas greater than 1 centimeter. Eighty-four patients were treated with total mastectomy and axillary dissection. Seven patients were treated with wide excision, axillary dissection and radiation therapy. Nine patients underwent lesser treatments. Among the 91 patients undergoing axillary dissection, 82 were node negative, eight had one to three positive nodes, and one had four or more positive nodes. One hundred percent of patients with ductal carcinoma in situ who underwent axillary dissections (24 of 31) were node negative. Only two patients received adjuvant hormonal therapy, and one woman received adjuvant chemotherapy. All patients were under observation for at least five years or to the time of death (mean follow-up period, 5.8 years). Of the 100 patients with complete follow-up, 92 are alive and disease free. Four patients with carcinoma that metastasized have died. Three patients are alive with known recurrence. One patient died of other causes six months after carcinoma was diagnosed. Widespread use of screening mammography coupled with judicious use of needle-localization biopsy will lead to the early diagnosis of carcinoma of the breast. Such early diagnosis of carcinoma does lead to an excellent (95 percent) five-year survival rate.

Complications from heparin-induced thrombocytopenia in patients undergoing cardiopulmonary bypass.

The purpose of this study was to evaluate retrospectively the incidence and severity of heparin-induced thrombocytopenia (HIT)-related complications in patients undergoing cardiopulmonary bypass. We reviewed the records of 1,500 consecutive patients who underwent cardiopulmonary bypass between August 1987 and December 1991 at Thomas Jefferson University Hospital. During this period of time, there were 1,155 coronary artery bypass graft operations (77 percent); 225 valve replacements and repairs, or both (15 percent); 60 combination coronary artery bypass graft or valve operations, or both (4 percent); and 60 miscellaneous procedures (4 percent). Although not all patients with postoperative complications were tested for the HIT antibody, 11 patients (0.75 percent) were diagnosed with HIT. There were 17 complications in these 5 men and 6 women including 6 cases of ischemic limbs which required amputation, 4 strokes, 2 instances of saphenous vein graft occlusion with resulting myocardial infarction, 2 cases of pulmonary emboli, 1 case of phlegmasia cerulea dolens, and 2 deaths. The complications occurred an average of 3.6 days postoperatively, with a range of occurrence of 1 to 11 days postoperatively. The mean nadir platelet count at the time of recognition was 123,000/mm3 (range 32,000 to 193,000/mm3) with 9 of 11 patients (81.8 percent) having counts greater than 100,000/mm3. There was, however, a mean percent decrease in the platelet count of 50 percent (range, 31 to 75 percent) from the time of first exposure to heparin to the time of recognition of HIT. In our patients, HIT was not related to the type, duration of treatment with or amount of heparin, or to pretreatment with aspirin.

Mammographically detected carcinoma of the breast.

A ten year experience with 2,077 consecutive mammographically guided needle-localization biopsies at a large community hospital is presented. By using this technique, 13.8 per cent of the biopsies were positive, yielding 284 carcinomas. The nonpalpable carcinomas discovered by mammography and the needle-localization technique were compared with those palpable carcinomas diagnosed during the same time period at York Hospital. In the final year of the study, 42.1 per cent of carcinomas treated at the York Hospital were diagnosed by the needle-localization technique. The mammographically detected carcinomas were smaller, more often node-negative and found, on average, at an earlier patient age than palpable carcinomas. The results of this study demonstrate that screening mammography, coupled with an aggressive biopsy policy, will lead to the discovery of many early, node-negative carcinomas of the breast.

Early detection of occult breast cancer: the York experience with 678 needle localization biopsies.

Mammographic needle localized breast biopsies (NLB) have been shown in university referral practices to allow early detection of occult neoplasms. A 6 year experience with NLB in a large community hospital with 678 patients is presented. Seventy eight (11.5%) proved to be cancer. Eighty nine per cent were node negative. A total of 70.5 per cent were "minimal" breast cancer. In the final year of the study, occult neoplasms comprised 25.5 per cent of newly diagnosed breast cancers. An aggressive biopsy policy toward mammographic abnormalities can lead to earlier diagnosis and treatment of malignant neoplasms at a favorable stage.

Hepatocyte changes following selenium accumulation in a freshwater teleost.

This report provides morphological and analytical data for a group of green sunfish collected from an area relatively free of metals and a second group of the same species collected from a lake into which selenium had been discharged. Neutron activation data of livers (and kidneys) collected from these fish show an average of about 11 ppm selenium (fresh weight) for both organs; other metals were not detected in the liver (or kidneys) of these fish. Ultrastructural examination of livers from fish of this group showed focal necrosis, areas of granular cytoplasm, fatty infiltration, increased numbers of Kupffer cells, and disorganized liver architecture--compared with those of controls. The presence of massive levels of selenium in the liver and concomitant hepatocyte changes suggests a causal relationship between these phenomena.