Lymphoscintigraphy with sentinel lymph node biopsy in cutaneous Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare cutaneous malignancy characterized by an aggressive clinical behavior with high rates of locoregional and systemic recurrence. Regional disease and distant metastases are associated with poor prognosis. Despite a predisposition of MCC to spread via the lymphatics, prophylactic lymph node dissection in the absence of clinically apparent lymph node involvement is controversial. The value of lymphoscintigraphy in cutaneous melanoma is established in lesions with ambiguous lymphatic drainage patterns. When used with sentinel lymph node biopsy (SLNB), it can identify subjects with occult regional node metastasis. The authors present 2 patients with MCC who underwent regional node staging with lymphoscintigraphy-directed SLNB. Both patients had sentinel nodes that were positive for metastatic disease. In patients with MCC, minimally invasive regional node staging SLNB may be useful in limiting the sequelae of routine lymphadenectomies. Whether early identification and treatment of patients with occult regional node disease can influence survival in MCC is not known.

Islet amyloid and islet amyloid polypeptide in cynomolgus macaques (Macaca fascicularis): an animal model of human non-insulin-dependent diabetes mellitus

To further characterize spontaneous diabetes mellitus in cynomolgus macaques (Macaca fascicularis) as a model for human non-insulin-dependent diabetes mellitus (NIDDM), we evaluated the morphologic characteristics of the endocrine pancreas of 4 diabetic and 12 age-matched nondiabetic cynomolgus macaques. In addition, the cDNA-predicted amino acid sequence for islet amyloid polypeptide (IAPP) of this species was determined. Islet amyloid deposits exhibiting typical congophilia and green birefringence were found in 4/4 diabetic animals and in 8/12 nondiabetics. Islet amyloid deposits were significantly more extensive in the diabetic macaques (P = 0.001), in which they occupied a mean of 60% of the islet area. In contrast, in the nondiabetic group the maximum islet area occupied by amyloid was 24% (group mean = 6.8%), with four animals having no detectable islet amyloid. Amyloid deposits consistently showed immunoreactivity for IAPP but not for insulin. Comparisons between group means for diabetic versus nondiabetic macaques showed significantly greater islet area (P = 0.01, 85,390 versus 36,540 microns 2) and significantly greater islet area fraction (P = 0.02, 0.065 versus 0.032) for the diabetic group. The cDNA-predicted amino acid sequence for cynomolgus IAPP was identical to that previously reported for pig-tail macaques (M. nemestrina) and had 92%, 86%, and 84% amino acid sequence identity with human, domestic cat, and murine IAPPs, respectively. These findings support the use of cynomolgus macaques as an animal model of human NIDDM.

The effects of hormone replacement therapy on carbohydrate metabolism and cardiovascular risk factors in surgically postmenopausal cynomolgus monkeys

Controversy exists regarding the effects of estrogen and estrogen/progestin replacement therapies on glucose tolerance and insulin resistance. Also unknown are whether changes in glucose tolerance and insulin resistance with hormone therapy affect arterial glycation and atherosclerosis. We studied ovariectomized female monkeys fed a lipid-lowering diet and given either no hormone replacement therapy (n = 25) or conjugated equine estrogens (CEE) alone (n = 22) or combined with medroxyprogesterone acetate ([MPA] n = 21) for 30 months. Monkeys receiving combined hormone replacement had significantly higher fasting glucose and insulin levels and higher insulin responses to a glucose challenge compared with controls or those given estrogen alone. Monkeys given estrogen-only therapy had lower body weights, lower measures of abdominal adiposity, and decreased serum androgen concentrations. However, due to the effective dietary lipid decrease, there was no additional effect of hormone treatment on atherosclerosis. Also, there was no correlation between either arterial glycation or insulin levels and atherosclerosis extent. Thus, although there were adverse effects of combined hormone replacement therapy on carbohydrate metabolism, we were unable to determine whether these effects altered the extent of atherosclerosis.

The effects of hormonal replacement therapy on insulin sensitivity in surgically postmenopausal cynomolgus monkeys (Macaca fascicularis)

OBJECTIVE

Our purpose was to evaluate the effect of hormone replacement therapy on insulin resistance in postmenopausal cynomolgus monkeys (Macaca fascicularis).

STUDY DESIGN

We studied 37 surgically postmenopausal cynomolgus monkeys that were fed a moderately atherogenic diet for 12 weeks with either no treatment (control), conjugated equine estrogens, medroxyprogesterone acetate, combination conjugated equine estrogens and medroxyprogesterone acetate, or tamoxifen. Insulin sensitivity and glucose effectiveness were determined by the frequent-sampling intravenous tolerance test by means of the minimal model analysis.

RESULTS

There were no differences in body weight, total plasma cholesterol, or body fat distribution between control and conjugated equine estrogens, medroxyprogesterone acetate, or combination treatment groups. However, compared with control animals (insulin sensitivity = 5.9 +2- 1.2 x 10(-4) min-1 microU-1 ml) or conjugated equine estrogens treatment (6.3 +/- 1.1 x 10(-4) min-1 microU-1 ml) insulin sensitivity was significantly decreased in animals treated with medroxyprogesterone acetate (2.9 +/- 0.4 x 10(-4) min-1 microU-1 ml, p < 0.001) or conjugated equine estrogens and medroxyprogesterone acetate (2.8 +/- 0.6 x 10(-4) min-1 microU-1 ml, p < 0.001). Although insulin sensitivity was shown to be decreased in the tamoxifen-treated animals (insulin sensitivity = 4.6 +/- 0.6 x 10(-4) min-1 microU -1 ml), the difference was not statistically significant compared with the control or conjugated equine estrogens-treated animals. No significant differences were seen for glucose effectiveness comparing control animals (glucose effectiveness = 0.043 +/- 0.006 min-1) to animals treated with medroxyprogesterone acetate (glucose effectiveness = 0.046 +/- 0.009 min-1), conjugated equine estrogens and medroxyprogesterone acetate (0.048 +/- 0.008 min-1) or tamoxifen (0.039 +/- 0.006 min-1).

CONCLUSION

These results suggest that progestins alone or in combination with estrogens can induce insulin resistance in postmenopausal monkeys while having no effect on plasma lipid concentrations or glucose effectiveness.

Chronic hyperglycemia increases arterial low-density lipoprotein metabolism and atherosclerosis in cynomolgus monkeys

Diabetes mellitus confers a threefold to fivefold increased risk of mortality from vascular disease. The primary cause of this increased incidence of vascular disease is atherosclerosis, but the mechanisms accounting for the increase are unclear. Chronic hyperglycemia is a common feature of all forms of diabetes mellitus and may contribute greatly to the increased incidence of atherosclerosis, via promotion of both lipoprotein and tissue glycation, which may have atherogenic effects. The present study investigated the effect of chronic hyperglycemia on measures of low-density lipoprotein (LDL) metabolism and atherosclerosis in streptozotocin-induced diabetic (STZ-DM) and control cynomolgus monkeys after 6 months of study. Consistent with a chronic hyperglycemic state, diabetic monkeys had significant increases in glycated hemoglobin (GHb) and glycated plasma LDL concentrations, but had minimal changes in total plasma cholesterol (TPC) or triglyceride (TG) concentrations during the study. Forty-eight hours before necropsy, control and in vitro-glycated LDL were differentially radiolabeled and coinjected into diabetic and control monkeys. There was a significant increase in arterial LDL accumulation in femoral arteries from diabetic monkeys compared with controls, with similar trends in other arterial sites. The effect of LDL glycation on arterial LDL accumulation was minimal in both groups. Arterial segments from diabetic monkeys also had greater amounts of arterial cholesterol content compared with controls. Histomorphometric analyses showed that diabetic monkeys had significantly greater intimal areas in the femoral artery and abdominal aorta compared with controls. Diabetic monkeys also had reduced arterial remodeling, or compensation, in the femoral artery and abdominal aorta. However, there was no difference in advanced glycation end products (AGE) in arterial collagen between groups. In conclusion, experimentally induced diabetes mellitus increases arterial LDL accumulation and atherosclerosis extent in cynomolgus monkeys before changes in AGE formation. The increased atherogenesis may be due to changes in lipoproteins or direct effects of hyperglycemia on the artery wall.

Clinical utility of open lung biopsy for undiagnosed pulmonary infiltrates

Open lung biopsy (OLB) is often performed as the definitive diagnostic procedure in patients with undiagnosed pulmonary infiltrates, but controversy exists as to the clinical utility of this practice. A retrospective review of 50 consecutive patients who underwent OLB for undiagnosed pulmonary infiltrates was done to assess the diagnostic value as well as the frequency with which these results affected therapy and mortality. Histologic tissue diagnoses were obtained in all patients. Specific pathologic diagnoses were obtained in 56% of patients, nonspecific in 44%. Lobar or lateralized infiltrates were more likely to yield a specific diagnosis (87%) than diffuse, bilateral infiltrates (42%). Thirty-four patients (68%) had previously had a nondiagnostic transbronchial biopsy; 58% of these patients had a specific diagnosis established by OLB. Twelve patients (24%) were in acute respiratory failure at the time of OLB; this group had a 50% mortality rate as compared with only 2.6% for patients not in acute respiratory failure (p less than 0.01). Therapy was altered (new specific or nonspecific treatment initiated or therapy withdrawn) in 78% of patients undergoing OLB. Thirty-day in-hospital survival was significantly higher in patients for whom either specific or nonspecific therapy was indicated and initiated versus those in whom no therapy was initiated or all therapy was withdrawn (mortality: 5.5% versus 35.7%; p = 0.01). Mortality was not related to the presence of immunosuppression or to the finding of a specific diagnosis. The overall mortality rate of 14% in this series compares favorably with mortality rates found in similar series, reflecting differences in patient populations and possibly the timing of intervention. OLB remains a clinically valuable diagnostic tool in selected patients.

The tensor fascia lata free flap in abdominal-wall reconstruction

The pedicled tensor fascia lata flap (TFL flap) is a method of choice for abdominal-wall reconstruction. Frequently, the size and location of the defect produce this option. Microsurgical transfer may overcome these disadvantages. Therefore, the ability of the TFL free flap to reconstruct complex abdominal wounds was evaluated. Seven patients with full-thickness abdominal-wall defects reconstructed by TFL free flaps were reviewed. Their average age was 44.6 years (range: 27 years to 59 years); follow-up averaged 10.5 months (range: 2 months to 18 months). Fifty-seven percent of the wounds were either infected or contaminated; the defect averaged 15 cm x 26 cm Six 85.7 percent) of the wounds involved the epigastrum. No total flap loss was seen, but three flaps developed distal tip necrosis (42.9%). Microsurgical transfer of the TFL free flap overcomes the limitations of the arc of rotation seen with the pedicled flap. It increases the vascularity of the distal portion of the flap. The TFL free flap is therefore an option in abdominal wounds, particularly those with defects of large size or supraumbilical location.

Critical analysis of results of craniofacial surgery for nonsyndromic bicoronal synostosis

We retrospectively assessed the intermediate and long-term results of craniofacial surgery in 22 consecutive patients with nonsyndromic bicoronal synostosis to determine the outcome of corrective surgery. The study population consisted of 13 males and 9 females whose ages ranged from 6 weeks to 24 months (mean, 5.6 months) at the time of initial surgery. All patients had been assigned a diagnosis of nonsyndromic bicoronal synostosis. Each patient underwent resection of both coronal sutures and frontal orbital advancement with cranial vault remodeling using a floating forehead technique. Age at initial operation was 5 months or less in 13 patients and 6 months or more in 9. Complications occurred in 5 patients (23%), and 1 patient with an associated metabolic disorder died from respiratory arrest postoperatively. Follow-up ranged from 6 to 168 months (mean, 53.2 months). Results were graded according to the need for and extent of reoperation. Residual aesthetic deformities were documented in 12 patients (55%). Three patients (14%) required calvarial recontouring or cranioplasty to achieve satisfactory forehead contour or bony continuity. Total reoperation for recurrent deformity was required at a mean age of 29.7 months in 8 patients (36%) and is pending in another (4%). Four patients (18%) required a third operation (two total reoperations and two cranioplasties) to achieve satisfactory results. Eight of 13 patients (62%) operated on at 5 months of age or younger required total reoperation compared with 1 of 9 (11%) operated at 6 months of age or older. When analyzed alone, age of operation was a statistically significant determinant of the need for reoperation (p < 0.03). However, when subjected to multivariate analysis, neither age at operation nor the presence of an associated anomaly or positive family history had a significant effect on outcome.

Esterified estrogens with and without methyltestosterone decrease arterial LDL metabolism in cynomolgus monkeys

Although both epidemiological and experimental evidence suggests that estrogen replacement therapy reduces the risk of coronary heart disease, the mechanisms for this beneficial effect are largely unknown. Furthermore, the addition of progestins or androgens to estrogen replacement therapy is of concern. The objective of this study was to examine the effects of esterified estrogens alone or in combination with an androgen on arterial LDL metabolism and early atherogenesis in ovariectomized female cynomolgus monkeys. Arterial LDL metabolism was assessed by using dual-labeled LDL that was injected 24 hours before necropsy. Arterial LDL degradation was reduced by 64% to 84% and cholesteryl ester content was decreased by approximately 50% in the thoracic aorta in both treatment groups compared with controls. In addition, aortic lipid peroxidation products, as assessed by thiobarbituric acid reaction, were significantly lower in animals treated with esterified estrogens, with a similar trend for combined estrogen-androgen treatment. Both treatments also reduced plasma concentrations of apoB-containing lipoproteins, reduced LDL particle size, and increased total-body LDL catabolism. The combination of decreased arterial LDL metabolism, decreased arterial lipid peroxidation, and improved plasma lipoprotein metabolism may explain some of the protective effects of estrogens on coronary heart disease and indicate that beneficial actions extend to a combination of estrogen and androgen.

A comparative study of homeless, previously homeless, and never homeless school-aged children's health

The purpose of this cross-sectional study was to compare the mental health, physical health, and healthcare practices of homeless, previously homeless, and never homeless poor school-aged children. The sample was comprised of 134 children who ranged in age from 8 to 12 years. The children participated in health assessments and completed two psychometric tests: the Children's Depression Inventory (CDI) (Kovacs, 1985) and the Revised Children's Manifest Anxiety Scale (RCMAS) (Reynolds & Richmond, 1985). Their mothers completed the Child Behavior Problem Checklist (CBCL) (Achenbach, 1991) and participated in an interview. The homeless (n = 67), previously homeless (n = 30), and never homeless children (n = 37) were similar in regard to their health assessment findings, reported health problems, healthcare practices, and CBCL scores. The proportions of homeless and previously homeless children with CDI scores in the clinical range were significantly greater than the never homeless poor children. The homeless children had significantly higher anxiety scores than the previously homeless and never homeless children. All three groups of children were at risk for physical and mental health problems; however, the findings suggest that school-aged children who experience homelessness may be at greater risk for depression and anxiety than never homeless poor children.

Characterization of the components and activity of Sonchus yellow net rhabdovirus polymerase

Sonchus yellow net virus (SYNV) is the best-characterized member of a group of plant rhabdoviruses that replicate in the host cell nucleus. Using a recently developed method for partial purification of active SYNV polymerase by salt extraction of nuclei from infected plant tissue (J. D. O. Wagner et al, J. Virol. 70:468-477, 1996), we have identified the nucleocapsid (N), M2, and L proteins as polymerase complex components (based on copurification with the polymerase activity and by coimmunoprecipitation assays). Furthermore, the L protein was shown by antibody inhibition analysis to be a functional component of the polymerase. A second complex of M2 and L proteins, thought to be a precursor to the polymerase complex, was also identified. In addition, we conducted a detailed characterization of SYNV RNA synthesis in vitro. The results demonstrate that the RNAs are transcribed sequentially, beginning with the N mRNA and followed successively by the remaining five mRNAs in the order of their genome organization. Gene expression conforms to a cascade pattern, with synthesis of the 3'-proximal N mRNA occurring at the highest level, followed by consecutively lower levels of transcription from each subsequent gene. The reaction conditions favor transcription over minus-sense RNA replication, which, we posit, is inhibited near specific signal sequences located on the antigenomic template. The results support the concept that the mechanism of transcription is highly conserved among diverse rhabdoviruses and are compatible with a unified model for the regulation of genomic and antigenomic RNA synthesis.

Regional differences in arterial low density lipoprotein metabolism in surgically postmenopausal cynomolgus monkeys. Effects of estrogen and progesterone replacement therapy

To determine if arterial lipoprotein metabolism may be involved in mediating well-known anatomic regional differences in susceptibility to atherosclerosis, arterial low density lipoprotein (LDL) metabolism and extent of atherosclerosis were studied in 17 ovariectomized female cynomolgus monkeys. The animals were fed an atherogenic diet for 18 weeks, during which time one group received 17 beta-estradiol and cyclic progesterone treatment (n = 9) and the controls received no hormone replacement therapy (n = 8). As reported previously, hormone replacement markedly reduced the accumulation of LDL in coronary arteries without affecting plasma lipoprotein patterns. We report here that LDL metabolism differed among arterial sites. LDL accumulation, LDL degradation rate, and the concentration of undegraded LDL were greatest in the coronary arteries and carotid bifurcations compared with the aorta, iliac arteries, and cerebral arteries. Although hormone replacement decreased indexes of LDL metabolism, there was no effect on intimal thickness or indexes of endothelial injury, such as leukocyte adhesion and endothelial cell turnover rate. There were, however, regional differences in these morphological parameters. The intima was thickest in the aorta, and leukocyte adhesion and endothelial cell turnover rates were greatest in the carotid bifurcation and thoracic aorta. The decreased accumulation and metabolism of LDL caused by hormone replacement therapy was specific to the arterial system and did not occur in the liver or other peripheral tissues.

Effects of 17 alpha-dihydroequilenin sulfate on atherosclerotic male and female rhesus monkeys

OBJECTIVES

Our purpose was to determine the effects of 17 alpha-dihydroequilenin on plasma lipid and lipoprotein, glucose, and insulin concentrations; coronary artery vasomotor function; and reproductive organ and mammary gland proliferation in atherosclerotic male and female rhesus macaques.

STUDY DESIGN

Fifty adult female and 33 adult male rhesus macaques were randomized to treatment by lifetime dietary cholesterol exposure and ratio of total plasma cholesterol to high-density lipoprotein cholesterol. The female treatment groups were intact female controls (n = 9), ovariectomized controls (n = 16), ovariectomized plus 0.3 mg/kg/day 17 alpha-dihydroequilenin (n = 17) and ovariectomized plus subcutaneous estradiol (n = 7). The male treatment groups were control (n = 16) and 1.25 mg/kg/day 17 alpha-dihydroequilenin (n = 17). Treatment lasted 5 weeks. Longitudinal assessments of plasma lipid and lipoprotein and glucose and insulin concentrations were performed. Coronary artery vasomotor function was assessed by quantitative coronary angiography 1 week after initiation of treatment. Morphologic and immunohistochemical assessments of proliferation index values of reproductive organs and mammary glands were done at necropsy.

RESULTS

17 alpha-Dihydroequilenin prevented endothelium-dependent vasoconstriction in males (p < 0.05) and ovariectomized females (p < 0.08). 17 alpha-Dihydroequilenin treatment increased plasma apolipoprotein A-1 concentrations (p < 0.05) and lowered fasting insulin concentrations (p < 0.05) without changing fasting plasma glucose concentrations in males. 17 alpha-Dihydroequilenin had no other effects on plasma lipid and lipoprotein concentrations in either males or females. It had no trophic effects on uterus, endometrium, or breast. There was no effect on either prostatic or testicular weight.

CONCLUSION

17 alpha-Dihydroequilenin may represent a single-agent hormone therapy for reduction of ischemic hear disease risk for both menopausal women and men. It has no apparent trophic effects on reproductive organs or mammary glands of female and male rhesus macaques.

Predictive factors for functional recovery after free tissue transfer oromandibular reconstruction

BACKGROUND

Recovery of upper aerodigestive tract function after reconstruction of segmental oromandiblectomy defects is frequently incomplete. The purpose of this study was to quantitate postreconstruction function and define variables that predict functional outcome in this population.

METHODS

A prospective study of 21 patients who underwent microvascular free tissue transfer reconstruction of segmental oromandibular defects was performed. Measures of swallowing, speech, bite, and oral intake were performed preoperatively and at 1, 3, 6, and 12 months postoperatively or until plateau. Preoperative versus maximal postoperative measures were compared and correlated with nine potentially predictive variables. Univariate and multivariate analyses were performed to determine the most significant predictive factors.

RESULTS

Baseline function in the study population was abnormal. Postoperative bite force improved, but swallowing, speech, and oral intake were worse than preoperative. Significant (univariate) predictors of outcome included diagnosis of cancer, tongue resection, pharynx resection, and flap skin paddle area. Only tongue resection remained significant in multivariate analysis.

CONCLUSIONS

Increasing need for oropharyngeal lining replacement, especially after tongue resection, is the most important predictor of functional outcome in reconstruction of segmental mandible defects.

Relationship between fractional pancreatic beta cell area and fasting plasma glucose concentration in monkeys

AIMS/HYPOTHESIS

We sought to establish the relationship between fasting plasma glucose concentrations and pancreatic fractional beta cell area in adult cynomolgus monkeys (Macaca fascicularis).

METHODS

Fasting plasma glucose and pancreatic fractional beta cell area were measured in 18 control and 17 streptozotocin-treated adult primates (17.0 +/- 1.2 vs 15.4 +/- 1.2 years old).

RESULTS

Fasting plasma glucose was increased (12.0 +/- 2.0 vs 3.4 +/- 0.1 mmol/l, p < 0.01) and fractional beta cell area was decreased (0.62 +/- 0.13% vs 2.49 +/- 0.35%, p < 0.01) in streptozotocin-treated monkeys. The relationship between fasting plasma glucose and pancreatic fractional beta cell area was described by a wide range of beta cell areas in controls. In streptozotocin-treated monkeys there was an inflection of fasting blood glucose at approximately 50% of the mean beta cell area in controls with a steep increase in blood glucose for each further decrement in beta cell area.

CONCLUSIONS/INTERPRETATION

In adult non-human primates a decrement in fractional beta cell area of approximately 50% or more leads to loss of glycaemic control.

Extraction of nuclei from sonchus yellow net rhabdovirus-infected plants yields a polymerase that synthesizes viral mRNAs and polyadenylated plus-strand leader RNA

Although the primary sequence of the genome of the plant rhabdovirus sonchus yellow net virus (SYNV) has been determined, little is known about the composition of the viral polymerase or the mechanics of viral transcription and replication. In this paper, we report the partial isolation and characterization of an active SYNV polymerase from nuclei of SYNV-infected leaf tissue. A salt extraction procedure is shown to be an effective purification step for recovery of the polymerase from the nuclei. Full-length, polyadenylated SYNV N and M2 mRNAs and plus-strand leader RNA are among the products of the in vitro polymerase reactions. Polyadenylation of the plus-strand leader RNA in vitro is shown with RNase H and specific oligonucleotides. This is the first report of a polyadenylated plus-strand leader RNA for a minus-strand RNA virus, a feature that may reflect adaptation of SYNV to replication in the nucleus. Analysis of the SYNV proteins present in the polymerase extract suggests that the N, M2, and L proteins are components of the transcription complex. Overall, the system we developed promises to be useful for an in-depth characterization of the mechanics of SYNV RNA synthesis.

Influence of caloric restriction on the development of atherosclerosis in nonhuman primates: progress to date

Caloric restriction (CR) has been observed to retard aging processes and extend the maximum life span in rodents. In an effort to evaluate the effect of this nutritional intervention on physiologic variables in higher species, several nonhuman primate trials are ongoing. In particular, a study evaluating the independent effect of CR on the extent of atherosclerosis was initiated in 1993 in 32 adult cynomolgus monkeys. Therefore, the trial was designed to achieve identical cholesterol intake after animals were randomized to a control group or a calorie-restricted group (30% reduction from baseline caloric intake). The animals were routinely evaluated for glycated proteins, plasma insulin and glucose levels, insulin sensitivity, and specific measures for abdominal fat distribution by CT scans over a 4-year interval. The results from 4 years of intervention demonstrate that CR improves cardiovascular risk factors (such as visceral fat accumulation) and improves insulin sensitivity. In contrast to other primate studies with normolipidemic animals, CR had no independent effects on plasma lipid levels and composition in the presence of equivalent amounts of dietary cholesterol intake. Preliminary analysis of atherosclerotic lesion extent in the abdominal aorta has failed to demonstrate differences between control animals and CR animals. Follow-up studies are being conducted to determine the effect of CR on atherosclerosis extent in coronary and carotid arteries.

Soy protein reduces the arterial low-density lipoprotein (LDL) concentration and delivery of LDL cholesterol to the arteries of diabetic and nondiabetic male cynomolgus monkeys

We have previously shown that soy protein consumption improves lipoprotein concentrations and reduces the progression of atherosclerosis in cynomolgus monkeys. The mechanism for these beneficial effects is unclear. The purpose of this study was to determine potential mechanisms for the atheroprotective effects of soy and to determine if these effects extend to diabetic monkeys. We designed an experiment with a 2 x 2 factorial design in which adult male monkeys (N = 23) were fed an atherogenic diet with a protein source of either soy isolate or casein and lactalbumin, and the monkeys were either control or streptozotocin-induced diabetic. Diabetics had significantly increased fasting glucose and glycated hemoglobin (GHb) levels; this relationship was not affected by the type of dietary protein. Diabetics also had increased total (TC) and low-density lipoprotein cholesterol (LDLC) concentrations. However, soy consumption significantly reduced TC and LDLC concentrations in both control and diabetic monkeys. Plasma and arterial LDL metabolism was determined by injecting 125I-LDL at 48 hours and 131I-tyramine cellobiose LDL at 1 hour prior to necropsy. This allowed a determination of the arterial LDL concentration, permeability, and arterial LDL delivery. An increase in the whole-body plasma LDL fractional catabolic rate (FCR) was found with soy. Soy significantly reduced the arterial LDL concentration across all arterial sites by an average of 50%. Soy also significantly reduced the delivery of LDLC to all arterial sites by an average of 40%. While this was primarily due to the lower plasma LDLC concentration, LDL permeability in the carotid bifurcation and internal carotid arteries was also reduced. There was no additional effect of diabetes. These beneficial effects on plasma and arterial LDL metabolism would be expected to reduce atherosclerosis and were found in both control and diabetic monkeys.

Preclinical profiles of progestins used in formulations of oral contraceptives and hormone replacement therapy

Progestins used in oral contraceptive formulations available in the United States include norgestimate, desogestrel, norethindrone, norethindrone acetate, and levonorgestrel. Progestins used in the United States in continuous and intermittent formulations of hormone replacement therapy are norgestimate, medroxyprogesterone acetate, and norethindrone acetate. The chemical structure of a progestin determines its relative binding affinity for the progesterone and androgen receptors, as well as the sex hormone binding globulin in human serum, and determines its clinical profile. Overall, the properties of levonorgestrel or norethindrone acetate in this regard differ from norgestimate and are more conducive to androgenic stimulation. Estrogen replacement offers cardioprotective effects in postmenopausal women. Progestins are added to hormone replacement therapy to counteract the well-known increased risk of endometrial hyperplasia associated with the use of unopposed estrogen. Animal models show that for some parameters, including improvement of lipid profiles, progestins can diminish the cardioprotective effect of estrogen. Initial animal studies of norgestimate combined with estrogen do not show an attenuation of estrogenic effects.

Mineralocorticoid therapy lowers serum potassium in patients with end-stage renal disease

Hyperkalemia is a commonly encountered problem in dialysis patients with end-stage renal disease. In this study we evaluated the effect of mineralocorticoid therapy (MCT; fludrocortisone 0.1-0.3 mg per os daily) on serum potassium of hyperkalemic end-stage renal disease patients. Consecutive monthly clinical and biochemical profiles 3-6 months before and after MCT were compared. Twenty-one patients with a mean age (+/- SE) of 54 +/- 4 years (11 male and 10 female) were studied. Two patients were dropped from this study because they required a change in prescription of dialysis after starting MCT. Mean serum potassium levels significantly fell (p < 0.001) during the post-MCT period (4.9 +/- 0.1 mEq/l) compared with potassium levels during the pre-MCT (5.6 +/- 0.1 mEq/l) period. All patients except 1 showed a reduction in serum potassium levels after MCT. Pre- and post-MCT values were not different for body weight, mean blood pressure, blood urea nitrogen, serum glutamic-oxaloacetic transaminase, lactate dehydrogenase, sodium, chloride, bicarbonate, creatinine and albumin. Since the majority of the patients were anuric (n = 15), a decrease in serum potassium values in the post-MCT period was not due to loss of potassium in the urine. MCT appears to decrease serum potassium values in patients with end-stage renal disease by extrarenal mechanisms. We conclude that MCT can be used safely to lower serum potassium in patients with end-stage renal disease.

Preoperative laboratory testing for the oral and maxillofacial surgery patient

Studies estimate that approximately 60% of preoperative testing could be eliminated without adversely affecting patient care. Unnecessary testing tends to cause extra risk to the patient, inefficient operating room schedules, and unnecessary costs. These extra tests may be hazardous to patients because of the pursuit and treatment of borderline positive or false-positive results. Furthermore, extra testing may also increase medicolegal risk, because the abnormalities that are discovered are usually not noted on the chart. A reliable and effective method for ordering laboratory tests to assess patients preoperatively and reduce morbidity and cost is presented.

Glycation of plasma low density lipoproteins increases interaction with arterial proteoglycans

The increased susceptibility to atherosclerosis of diabetic individuals, may result from diabetes-associated modification in plasma low density lipoproteins (LDL) which enhance their interaction with arterial extracellular matrix proteoglycans. Using a nonhuman primate model for human diabetes, studies were conducted to examine diabetes-induced changes in LDL. Plasma LDL were isolated from control (n = 4) and streptozotocin-induced diabetic (n = 3) cynomolgus macaques by differential ultracentrifugation. An in vitro binding assay was used to measure LDL interaction with arterial proteoglycans. Significantly more diabetic LDL bound to proteoglycans than control LDL (12.9+/-0.7 microg LDL cholesterol/microg proteoglycan versus 8.9+/-0.5 microg LDL cholesterol/microg proteoglycan (mean +/- S.E.M.), P < 0.005). Glycation of LDL, determined by fructosamine content, was significantly enhanced in diabetic versus control animals (37+/-3.1 versus 20+/-1.5 micromol/l (mean +/- S.E.M.) P < 0.005). The correlation coefficient between fructosamine content of LDL and its binding to arterial proteoglycans was 0.95. No LDL compositional variables other than glycation correlated with proteoglycan binding. Removal of the glycated portion of LDL from diabetic animals returned LDL proteoglycan binding to normal. These data demonstrate that the diabetes induced glycation of LDL increases its proteoglycan binding properties: thus, a critical mechanism in atherosclerosis, enhanced LDL interaction with arterial proteoglycans, may be accelerated by the diabetic state.

Insulin sensitivity and cardiovascular risk factors in ovariectomized monkeys with estradiol alone or combined with nomegestrol acetate

We have previously shown that medroxyprogesterone acetate (MPA), either alone or combined with conjugated equine estrogens (CEE), significantly decreased insulin sensitivity (SI), compared with both untreated controls and those treated with CEE alone. The purpose of this study was to determine the effects of estradiol (E2), with and without nomegestrol acetate (NA; a potent progestin that lacks androgenic activity), on SI and arterial antioxidant activity, as determined by F2-isoprostanes. Thirty-six adult female cynomolgus monkeys (Macaca fascicularis) were ovariectomized and fed a moderately atherogenic diet, with one of the following three treatments added to the diet, for 12 weeks: 1) no treatment (control); 2) E2; or 3) continuous combined E2 + NA (E2+NA). SI and glucose effectiveness were assessed by the frequently sampled i.v. glucose tolerance test using a third-phase insulin infusion after 10 weeks of treatment. Cholesterol content and F2-isoprostanes were measured in the thoracic aorta after 12 weeks of treatment. E2 treatment resulted in a significantly greater SI, compared with control or E2+NA-treated monkeys (10.03 +/- 0.91 vs. 6.35 and 6.49 x 10(-4) min(-1) microU(-1) mL; P < 0.05). In contrast to our studies of CEE and MPA, E2+NA treatment, though reducing the SI below that of the E2 group, did not reduce the SI below that of control monkeys. As expected, the short period of treatment resulted in no significant differences in aortic cholesterol content. There was no treatment effect on total F2-isoprostanes (representing F2-isoprostane formation caused primarily by autooxidation), suggesting minimal antioxidant activity. However, there was a treatment difference in the prostaglandin F2alpha (PGF2alpha) isomer (a prostaglandin (PG) isomer formed by both autooxidation of arachidonate and cyclooxygenase activity). PGF2alpha concentrations were 32% lower with E2 treatment, compared with controls, and 36% lower, compared with E2+NA treatment (0.48 +/- 0.08 vs. 0.71 +/- 0.12 and 0.75 +/- 0.06; P < 0.05), suggesting differences in PG synthesis between hormone treatments. In conclusion, NA, a progestin without androgenic activity, may still affect some cardiovascular risk factors differently than estrogen-only therapy. However, it seems to be less detrimental than MPA.

Effects of hormone replacement modalities on low density lipoprotein composition and distribution in ovariectomized cynomolgus monkeys

This study was designed to determine the effect of several hormone replacement therapies on LDL size, density, heterogeneity, and composition in surgically postmenopausal cynomolgus monkeys fed an atherogenic diet. Groups (n = 5 each) of ovariectomized cynomolgus monkeys were untreated (control), or treated with conjugated equine estrogens, medroxyprogesterone acetate (progesterone), combined estrogen-progesterone, or tamoxifen for 9 weeks. There were no differences among treatment groups in total plasma, LDL, or HDL cholesterol or triglyceride concentrations. Plasma LDL were isolated by ultracentrifugation and size exclusion chromatography and subfractionated by density gradient centrifugation for subsequent chemical analysis. Estrogen treatment was associated with significantly smaller (measured as LDL molecular weight, 3.9 +/- 0.2 g/mu mol) and denser plasma LDL (1.034 g/ml peak density) compared with control (4.5 +/- 0.1 g/mu mol; 1.030 g/ml peak density) or progesterone-treated animals (4.6 +/- 0.2; 1.029 g/ml peak density). LDL from the estrogen group were relatively enriched in protein and triglyceride and poor in cholesteryl ester and apolipoprotein F (apoE) compared to the control group. Triglyceride enrichment with estrogen treatment occurred predominantly in the lighter, larger LDL subfractions (d = 1.015-1.025 g/ml), which were reduced in concentration (26 +/- 10 mg cholesterol/dl) compared to control (61 +/- 19 mg/dl) or progesterone treated animals (67 +/- 16 mg/dl). Combined estrogen-progesterone or tamoxifen treatment resulted in changes in LDL that followed the same trend as those observed with estrogen treatment. We conclude that short-term estrogen treatment of ovariectomized cynomolgus monkeys results in changes in plasma LDL size, density, and composition while having no apparent effect on overall plasma lipid concentrations.