A family physician smoking cessation program: an evaluation of the role of follow-up visits

Our purpose in this randomized clinical trial was to compare a two-visit smoking cessation intervention by family physicians with the same intervention supplemented by additional follow-ups. Forty-one southern Ontario family physicians volunteered for the study and subsequently participated in a four-hour training program on smoking cessation techniques. Physicians advised patients who smoked and indicated an interest in attempting to quit with the help of their physician to stop smoking at the end of a regularly scheduled visit. Physicians instructed patients to make a specific appointment for an evaluation of their smoking habits. Six hundred forty-seven patients returned for that assessment and were than randomized into either the two-visit intervention group (with risk assessment, support, the setting of a cessation date, self-help literature, and a prescription for nicotine gum, where appropriate) or into the other intervention group (with the same maneuvers as well as the offer of four more supportive follow-up visits). We found no statistically significant difference in one-year, biochemically validated, sustained cessation rates between the group offered the long-term follow-up visits (12.5%) and the group given the brief intervention (10.2%). The 95% confidence interval on the difference between the groups was 2.8% in favor of the brief intervention group to 7.3% in favor of the group offered follow-up. The results do not support the value of long-term follow-up visits for smokers.

Is puberty a risk factor for eating disorders?

OBJECTIVE

To examine the association between stage of sexual maturation and eating disorder symptoms in a community-based sample of adolescent girls.

PARTICIPANTS

All sixth- and seventh-grade girls (N = 971) enrolled in four northern California middle schools.

MAIN VARIABLES EXAMINED

Pubertal development measured using self-reported Tanner stage and body mass index (kg/m2). The section of the Structured Clinical Interview for DSM-III-R Disorders (SCID) discussing bulimia nervosa was used to evaluate symptoms of bulimia nervosa.

RESULTS

Girls manifesting eating disorder symptoms, while not significantly older than their peers without such symptoms, were more developmentally advanced as determined with Tanner self-staging. The odds ratio for the association between sexual maturity and symptoms was 1.8 (95% confidence interval, 1.2 to 2.8); ie, at each age, an increase in sexual maturity of a single point was associated with a 1.8-fold increase in the odds of presenting symptoms. The odds ratio for the association between body mass index (adjusted for sexual maturity) and symptoms was 1.02 (95% confidence interval, 1.0 to 1.05). There was no independent effect of age or of the interaction between age and the sexual maturity index.

CONCLUSIONS

These results suggest that (1) puberty may be a risk factor for the development of eating disorders, and (2) prevention efforts might best be directed at prepubertal and peripubertal adolescents.

Physicians' and Nurses' Own Health Practices: A survey

We sent an anonymous self-report questionnaire on personal health practices to 141 nurses, 72 family physicians, and 171 specialists in the greater Hamilton area. All groups had similar lifestyle behaviors; differences between groups and between men and women were found for disease detection and prevention and health care use. Health professionals could significantly improve personal health practices, benefiting both themselves and their patients.

Effects of insulin-like growth factors (IGFs) and IGF receptor antibodies on the proliferation of human breast cancer cells

It has been shown previously that MCF-7 cells proliferate in response to nanomolar concentrations of IGF-I and IGF-II. It has also been reported that the actions of both peptides are mediated through the IGF-I receptor. To further characterize these observations, we used MCF-7 and Hs578T cell lines in the serum-free/phenol red-free system developed by Ogasawara and Sibarsku, 1988. Cell proliferation was studied in the presence of insulin, IGF-I and -II and a series of growth factor receptor antibodies. No effect was observed on Hs578T cell proliferation with any of the growth factors. However, MCF-7 cells were stimulated 4-5 fold with IGF-I and insulin, while IGF-II was only slightly less potent. alpha IR3, a monoclonal antibody directed against the IGF-I receptor, was stimulatory when added alone. However, alpha IR3 blocked approximately 50% of the IGF-I response, only 5% of the insulin response, and did not block the IGF-II effect on cell proliferation. These data suggest that alpha IR3 and IGF-I are acting as agonists through the IGF-I receptor, but that insulin and IGF-II are acting through other receptors. Two different IGF-II/M-6-P receptor antibodies and an insulin receptor antibody failed to significantly block IGF-II actions. All three antibodies were stimulatory when added alone. beta-gal inhibited 27% of the IGF-II response and had no effect when added alone. Since beta-gal decreases the binding affinity of the IGF-II/M-6-P receptor for IGF-II and does not bind to the IGF-I or insulin receptor, these data suggest the possibility that IGF-II mitogenic action is mediated through the IGF-II/M-6-P receptor. In summary, these data indicate that nanomolar concentration of insulin, IGF-I and IGF-II are potent mitogens in MCF-7 cells and can potentially stimulate cell proliferation through all three receptors.

Promoting Physical Activity in Primary Care: Overcoming the barriers

The principle barriers preventing health care professionals from promoting physical activity include an incomplete understanding of the evidence linking physical activity and health, difficulty in translating research findings into a feasible and efficacious clinical intervention, resistance to adopting a preventive orientation, and concerns about the risks of physical activity. Low level activities likely provide benefit with little risk.

Growth hormone therapy in hypophosphatemic rickets

The effects of growth hormone therapy on the biochemical measures of bone metabolism were studied in 11 children aged 3.5 to 17 years who had familial hypophosphatemic rickets; five were male. Subjects were maintained on a regimen of stable doses of conventional therapy (calcitriol and phosphate). Subjects were studied at baseline receiving conventional therapy and during three sequential treatment periods: no therapy (4 weeks), growth hormone only (0.05 mg/kg per day for 4 weeks), and conventional therapy plus growth hormone (2 weeks). The nine youngest subjects were continued on a regimen of triple therapy for an additional 24 weeks. Serum phosphate averaged 0.93 +/- 0.13 mmol/L (mean +/- SD) at entry and decreased when the subjects were not receiving any therapy. During the 4 weeks of growth hormone only treatment, phosphate rose in all 11 subjects (0.70 +/- 0.08 mmol/L to 0.83 +/- 0.08 mmol/L). With triple therapy, phosphate remained higher than with no therapy. Calcitriol, osteocalcin, and parathyroid hormone increased as the subjects received growth hormone alone. Insulinlike growth factor I z scores rose significantly in response to growth hormone therapy alone. All nine subjects receiving 6 months of triple therapy increased their growth rate z scores. Exogenous growth hormone therapy may be useful in familial hypophosphatemic rickets.

Effect of inhibition of converting enzyme on renal hemodynamics and sodium management in polycystic kidney disease

We compared the tubular transport of sodium and the erythrocyte sodium-lithium countertransport activity in hypertensive patients with autosomal dominant polycystic kidney disease (ADPKD) and in normotensive control subjects. In addition, we assessed the effects of inhibition of converting enzyme on renal hemodynamics and sodium excretion in hypertensive patients with ADPKD to provide information on mechanisms responsible for the increased renal vascular resistance and filtration fraction and the adjustment of the pressure-natriuresis relationship during saline expansion, observed in patients with ADPKD, hypertension, and preserved renal function. In comparison with normotensive control subjects, the hypertensive patients with ADPKD had lower renal plasma flows, higher renal vascular resistances and filtration fractions, and similar proximal and distal fractional reabsorptions of sodium. The administration of enalapril resulted in significant increases in the renal plasma flow and significant reductions in mean arterial pressure, renal vascular resistance, and filtration fraction, but the glomerular filtration rate remained unchanged. Despite the significant reduction in mean arterial pressure during inhibition of converting enzyme, the distal fractional reabsorption of sodium decreased while the total fractional excretion of sodium remained unchanged or increased slightly. No significant differences were detected between the normotensive control subjects and the hypertensive patients with ADPKD in erythrocyte sodium-lithium countertransport activity, plasma renin activity, plasma aldosterone concentration, or atrial natriuretic factor. These results suggest that the renal renin-angiotensin system plays a central role in the alterations in renal hemodynamics and sodium management associated with the development of hypertension in ADPKD.

Insulin-like growth factor-I as a reflection of body composition, nutrition, and puberty in sixth and seventh grade girls

Large variations in nutritional intake have profound effects on the GH-insulin-like growth factor-I (IGF-I) axis in children and adults, but the effect of normal variations in nutrition on IGF-I concentrations is largely unstudied, particularly during puberty. We measured serum IGF-I concentrations in 325 sixth and seventh grade girls (12.4 +/- 0.7 yr) at the beginning of a multisite school-based health curriculum. The mean serum IGF-I level among the 243 girls with complete data was 573 +/- 244 micrograms/L. Pubertal stage was significantly associated with IGF-I (P less than 0.0001, by analysis of variance). Mean concentrations rose from 427 +/- 198 micrograms/L among those at the earliest pubertal stages to 639 +/- 219 micrograms/L among the mature girls. After adjusting for the association with the stage of pubertal development, serum IGF-I was not significantly associated with measures of body composition (body mass index, triceps skin fold thickness, waist/hip ratio, height, and weight). Additionally, IGF-I concentrations were not associated with nutritional intake (total calories, total protein, total fat, and total carbohydrate) or such measures of nutrition as serum iron, hemoglobin, red cell mean corpuscular volume, white cell count, and cholesterol. IGF-I concentrations, however, were significantly correlated with transferrin concentrations, another possible index of nutritional status (r = 0.29; P less than 0.0001). IGF-I is not a clinically useful index of nutritional status among normal pubertal girls.

Eosinophiluria in atheroembolic renal disease

PURPOSE AND PATIENTS

Eosinophiluria has been reported in acute interstitial nephritis and other renal diseases, but its presence in atheroembolic renal disease (AERD) has not been previously established. AERD has been identified as a cause of acute and chronic renal failure, particularly in elderly patients with advanced atherosclerosis and in those patients who have undergone manipulation or intervention of the abdominal aorta, renal artery, or coronary artery. The definitive diagnosis is made by renal biopsy. However, many patients are too acutely ill to tolerate renal biopsy and, in recent years, peripheral eosinophilia, hypocomplementemia, and thrombocytopenia have been recognized in association with AERD. Previous studies have reported that AERD is associated with an inactive renal sediment and an absence of urine eosinophils. We reviewed our experience over a 4-year period with 24 patients with renal biopsy-proven AERD.

RESULTS

Urine eosinophils were evaluated in nine patients to help determine the cause of their renal deterioration. Seven of these patients presented with evidence of vascular disease. Three patients had procedures involving manipulation of the abdominal aorta. Physical examination revealed findings of atheroembolism in three of nine patients. Overall, eight of nine patients had a positive Hansel's stain for eosinophiluria. Six of eight patients had more than 5% of their urinary white cell count as eosinophils. The reason for failure of previous studies to detect eosinophiluria in AERD is unclear but may have been related to the use of Wright's stain instead of Hansel's stain.

CONCLUSION

In the evaluation of acute renal insufficiency, eosinophiluria may indicate AERD in addition to the other known causes for this finding.

Differential regulation of the insulin-like growth factors (IGF-I and -II) and IGF binding proteins during malnutrition in the neonatal rat

Insulin-like growth factor (IGF)-I and -II are known to play a major role in fetal and early postnatal growth. The IGF binding proteins (IGFBPs) are thought to be important in modulating the actions of the IGFs. In this paper, the effect of malnutrition in the neonatal rat on serum IGFs and IGFBPs and hepatic IGFBP messenger (m) RNA was examined. Control (C) dams (n = 9) were allowed ad libitum intake, whereas restricted (R) dams (n = 9) were limited to 50% of ad libitum intake throughout lactation, which results in decreased milk production and malnutrition of pups suckling on restricted dams. A subset of pups were cross-fostered from the R-dams to the C-dams from days 15-19 postpartum (PP) to investigate the effect of nutritional repletion (refed). Pups were killed on days 8, 12, 15, and 19 PP and liver and blood collected. Serum IGF-I and -II concentrations were measured by RIA after acid-chromatography to remove IGFBPs. Serum IGFBPs were characterized by Western ligand blot. Hepatic mRNA for IGFBP-1, -2, and -3 were determined by northern analysis. Body weight (BW) of R-pups was significantly less than C-pups by day 10 PP (P less than or equal to 0.05), and mean BW at day 19 was 56% of the C-pups. Refeeding from days 15-19 resulted in a significantly greater rate of growth vs. R-pups (3.2 vs. 0.9 g/day), and mean BW of refed pups at day 19 PP was 75% of C-pups. Malnutrition caused a significant reduction in both serum IGF-I and -II after day 12 PP, while causing an elevation in serum IGFBP-2. IGFBP-1 and IGFBP-2 mRNA expression were not significantly affected at days 8 and 12, but were elevated in livers of day 15 and 19 pups. Malnutrition caused a delay in the development shift from IGFBP-2 to IGFBP-3, which normally occurs between day 15 and 19 in the rat. Refeeding raised serum IGF-I and -II levels to those found in the C-pups and a trend toward normalization of IGFBP profiles. In conclusion, IGFs and IGFBPs are differentially regulated during neonatal malnutrition. The decrease in IGF peptide and induction of IGFBP-1 and -2 may provide protective mechanisms by inhibiting growth during malnutrition.

Modified enzyme-based colorimetric assay of urinary and plasma oxalate with improved sensitivity and no ascorbate interference: reference values and sample handling procedures

The measurement of oxalate in urine and plasma continues to be difficult, particularly in the presence of ascorbate. We have modified and validated a colorimetric assay involving the use of oxalate oxidase (EC 1.2.3.4). Modification of an HPLC spectrophotometric detector improved sensitivity (to as much as 1000-fold that of conventional spectrophotometers) and allowed measurement of oxalate concentrations less than 1 mumol/L. This provided more than enough sensitivity for measurement of normal concentrations of plasma oxalate. We established reference values for oxalate concentrations in urine and plasma, studied sample handling, and established conditions to avoid ascorbate interference in urine and plasma measurements. Mean analytical recovery of [14C]oxalate from plasma to the filtrate was 86 (SD 10)%; recovery of unlabeled oxalate from filtrate was 87 (SD 9)%. Urinary oxalate excretion rates in apparently healthy controls were 0.11-0.46 mmol/24 h. Plasma concentrations in control subjects were 2.5 (SD 0.7) mumol/L, similar to concentrations determined by recent gas chromatographic and isotope dilution methods. Frozen and acidified urine samples showed no interference from ascorbate when excess ascorbate was avoided. Ingestion of 2 g of ascorbate daily did not increase urinary oxalate in healthy control subjects, but during storage ascorbate was converted to oxalate in all conditions tested.

Impact of pubertal development on body fat distribution among white, Hispanic, and Asian female adolescents

Variation in the waist/hip ratio (WHR) may be related to changes in hormonal secretion associated with pubertal maturation. We therefore studied the effects of race, pubertal development, and body fatness on WHR during adolescence in a multiethnic population. A total of 688 white, Asian, and Hispanic female adolescents (mean (+/- SD) 12.4 +/- 0.7 years), participating in the evaluation of a multisite school-based health education program, were included in these analyses. Self-assessed stage of puberty and measurements of height, weight, waist circumference, and hip circumference were obtained from each participant. The WHR and age-adjusted body mass index were calculated. Analysis of covariance demonstrated that puberty significantly affects hip circumference and WHR but not waist circumference among female adolescents. Age and fatness, as reflected by age-adjusted body mass index, contributed significantly to both circumferences and to the WHR. There was a significant effect of ethnicity on hip circumference but not on waist circumference or the WHR. These results confirm that pubertal stage exerts a significant effect on the hip circumference and WHR in female adolescents, even after the effects of fatness and age are controlled. Studies of body fat distribution during late childhood and adolescence should include assessments of pubertal maturation.

Standardized percentile curves of body-mass index for children and adolescents

Weight-for-height indexes are often used in the clinical assessment of obesity in children and adolescents. The direct measurement of adiposity, using hydrostatic weighing and other techniques, is not feasible in studies involving young children or with large numbers of older subjects. Ratios of weight relative to height, such as the body-mass index (weight/height), may be used as indirect measures of obesity and correlate with more direct measures of adiposity. Using data from the First National Health and Nutrition Examination Study, 1971 to 1974, standardized percentile curves of body-mass index for white children and adolescents were developed. These curves may be used to monitor the body-mass index of white children and adolescents longitudinally and for comparing an individual with others of the same sex and age.

Patients' perspectives of a physician-delivered smoking cessation intervention

Forty-three patients--recipients of a highly structured, physician-delivered smoking cessation intervention--were interviewed using ethnographic (anthropological) research methods. We conducted interviews with patients after visits with the physician, then audiotaped and transcribed them. Discourse analysis of interview texts identified features and components of the physician maneuver most effective from the patients' point of view. Patients discussed two general areas of physicians' preventive activities: an interventionistic component (in which professional, diagnostic, and authoritative features were emphasized) and a personalistic component (in which physicians were experienced as equals, supportive, caring, empowering, and challenging). From the perspective of patients, the personalistic component of the physician-delivered smoking cessation maneuver appeared most effective. We conclude that, in clinical preventive medicine generally, patients (1) evaluate the kind of support they receive from their physician (e.g., degree of empathy, encouragement, and sincerity), (2) respond favorably to positive imagery in the challenge to alter their lifestyle, (3) look for a balance in the relationship established with their physician (negotiation, respect, mutual understanding, and rapport), and (4) remember the consistency and regularity of their physician's health promotion messages.

Oxalate, silicon and vanadium in acquired cystic kidney disease

We have investigated the importance of several clinical and laboratory parameters on the development of acquired cystic kidney disease (ACKD) as detected by ultrasonography in 19 patients who had received dialysis therapy for at least three years. We were particularly interested on the possible effect of the serum levels of oxalate and silicon, which can produce tubular obstruction, and that of vanadium, which can affect cell proliferation. The severity of ACKD increased with the duration of dialysis and was greater in men than in women. Positive correlations were observed between the grades of ACKD and the levels of hemoglobin, hematocrit, and parathyroid hormone, while there was a negative correlation between ACKD and serum ferritin levels. The serum levels of oxalate, silicon, and vanadium, pre- and postdialysis, were markedly and significantly higher than those in normal controls, but there was no significant correlation between these levels and the duration of dialysis therapy or severity of ACKD. The pre- and postdialysis levels of vanadium were not significantly different, while the levels of oxalate and silicon were significantly lower in the postdialysis samples. No significant correlations were detected between ACKD and age of the patients, blood pressure, protein catabolic rate, efficiency of dialysis index, or the serum levels of iron, sodium, potassium, calcium, phosphorus, aluminum, and beta 2-microglobulin.

Examination of potential mechanisms of carcinogenicity of 1,4-dioxane in rat nasal epithelial cells and hepatocytes

Several long-term studies with 1,4-dioxane (dioxane) have shown it to induce liver tumors in mice, and nasal and liver tumors in rats when administered in amounts from 0.5 to 1.8% in the drinking water (Argus et al. 1965; Kociba et al. 1974; National Cancer Institute, 1978). In order to examine potential mechanisms of action, chemically-induced DNA repair (as an indicator of DNA reactivity) and cell proliferation (as an indicator of promotional activity) were examined in nasal turbinate epithelial cells and hepatocytes of male Fischer-344 rats treated with dioxane. Neither dioxane nor 1,4-dioxane-2-one, one of the proposed metabolites, exhibited activity in the in vitro primary rat hepatocyte DNA repair assay, even from cells that had been isolated from animals given either 1 or 2% dioxane in the drinking water for 1 week to induce enzymes that might be responsible for producing genotoxic metabolites. No activity was seen in the in vivo hepatocyte DNA repair assay in animals given a single dose of up to 1000 mg/kg dioxane or up to 2% dioxane in the drinking water for 1 week. Treatment of rats with 1.0% dioxane in the drinking water for 5 days yielded no increase in liver/body weight nor induction of palmitoyl CoA oxidase, indicating that dioxane does not fit into the class of peroxisomal proliferating carcinogens. The percentage of cells in DNA synthesis phase (S-phase) was determined by administration of 3H-thymidine and subsequent quantitative histoautoradiography. The hepatic labeling index (LI) did not increase at either 24 or 48 h following a single dose of 1000 mg/kg dioxane.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-like growth factors are mitogenic for human keratinocytes and a squamous cell carcinoma

Normal adult human keratinocytes in monolayer culture and SCL-1, a skin-derived squamous-cell carcinoma cell line, were investigated for the expression of receptors for insulin-like growth factors (IGF) and insulin. As demonstrated by affinity crosslinking, radiolabeled IGF-1, IGF-2, and insulin bound specifically to both cell types. Each cell expressed type I IGF receptors, with affinity for IGF-1 greater than IGF-2 much greater than insulin. Insulin receptors, with highest affinity for insulin, were also present on both cells. However, keratinocytes and SCL-1 cells differed in 125I-IGF-2 binding. 125I-IGF-2-bound to both type I and type II IGF receptors in normal keratinocytes, but bound predominantly to membrane-associated IGF binding proteins in SCL-1. IGF-1 was slightly more potent than IGF-2 in stimulating growth of both keratinocytes and SCL-1 cells. In keratinocytes, concentrations of IGF-1 ranging from 5-100 ng/ml, and of IGF-2 from 50-100 ng/ml, resulted in a significant increase in cell number. At the maximum dose of 100 ng/ml, either IGF-1 or IGF-2 caused a 2.3-times increase in cell number. In SCL-1 cells, IGF-1 was more potent than IGF-2 or insulin at lower concentrations, but either IGF-1 or IGF-2 at the maximal concentration of 333 ng/ml stimulated a 4.7-times increase in thymidine incorporation. The stimulatory effect of insulin in SCL-1 was 10-50 times less potent than that of the IGF. The effect of either IGF on SCL-1 was completely inhibited by the type I IGF receptor antibody alpha IR-3, suggesting that both IGFs are mitogenic through the type I IGF receptor. Insulin action was partially blocked by alpha IR-3, suggesting that insulin can act through both the insulin and type I IGF receptors. It thus appears that IGF-1 and IGF-2 are mitogens for normal and transformed human keratinocytes and that their actions are primarily mediated through the type I IGF receptor, whereas insulin is a mitogen through both the IGF-1 receptor and the insulin receptor.

Insulin-like growth factors I and II and their binding proteins in rat milk

IGF-I and -II are peptide growth factors that may be important contributors to the growth-promoting properties associated with milk. IGF in extracellular fluids, including serum and milk, are carried by specific high-affinity binding proteins (IGFBP). In this study, the levels of IGF-I and -II in rat serum and milk were quantified by specific RIA, and the IGFBP were characterized using Western ligand blotting and autoradiography throughout lactation. The levels of IGF-I in both milk and maternal serum decreased during lactation. Serum IGF-I decreased from 743 +/- 187 micrograms/L on d 1 to 391 +/- 106 (mean +/- SD) on d 21 of lactation, and milk IGF-I levels fell from 30 +/- 10 to 13 +/- 8 micrograms/L. Levels of IGF-II in serum and milk were much lower than IGF-I, and were unaffected by lactation. In maternal serum, several IGFBP were identified: IGFBP-3, which migrates as four glycosylated bands with apparent Mr from 38 to 42 kD and one to two nonglycosylated bands with apparent Mr of 28 to 29 kD, and an IGFBP with an apparent Mr of 24 kD. In milk, IGFBP-3, the 24-kD binding protein, and a third IGFBP with an apparent Mr of 29 kD were identified. Treatment of milk and serum with Endoglycosidase F reduced the four glycosylated IGFBP-3 bands (38-42 kD) to two bands with apparent Mr of 35 and 32 kD. In rat milk, but not adult rat serum, the IGFBP with an apparent Mr of 29 kD was immunoprecipitable by an antibody that recognizes IGFBP-2.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and laboratory evaluation of renal stone patients

The management of renal lithiasis is a life-long proposition for most patients. Stone diseases are difficult for both patients and physicians to monitor and treat appropriately. The long-term management of metabolically active patients requires close association with a physician who is prepared to monitor stone formation, appropriate risk factors, and the progress of those risk factors over an extended time. Although this is a large economic commitment, it has been calculated that failure to carry out this responsibility is an even larger economic burden for patients and society. With aggressive risk factor management and follow-up, 95% of patients can become metabolically inactive. The long-term management of these patients, still evolving, is going to continue to require some assessment of the presence or absence of stones. The analysis of risk factors and the assessment of therapeutic maneuvers should continue to improve. It is possible that some specific index of risk factors for these patients will become readily available. Unfortunately, the efficacy of the ones currently available have not been clearly established.

Plasma prorenin activity and complications in children with insulin-dependent diabetes mellitus

BACKGROUND

Renin, secreted into the blood by the juxtaglomerular cells of the kidneys, is derived from a larger precursor, prorenin. Plasma prorenin activity is increased in patients with insulin-dependent (Type I) diabetes mellitus who have microvascular complications of their disease. We undertook this study to determine prospectively whether rising prorenin activity can predict the development of complications in young patients with Type I diabetes.

METHODS AND RESULTS

Plasma prorenin was measured in 135 children and adolescents with Type I diabetes. The mean (+/- SE) plasma prorenin activity among the 32 patients over the age of 10 years who had had uncomplicated diabetes for 0.1 to 5 years was 8.43 +/- 0.58 ng of angiotensin I per liter.second, as compared with 7.06 +/- 0.32 in 37 control subjects of the same age (P less than 0.05). In the 9 patients older than 10 who had retinopathy or overt albuminuria, the mean plasma prorenin activity was 13.09 +/- 1.43 ng of angiotensin I per liter.second (P less than 0.0001). In 34 patients 10 years old or older with uncomplicated diabetes, 3 to 13 measurements of plasma prorenin activity were taken during a follow-up period of 6 to 39 months. Urinary albumin was determined at each visit, and the patients had regular retinal examinations. Only 1 of the 20 patients who had consistently normal plasma prorenin values had overt albuminuria (ratio of urinary albumin to creatinine, greater than 0.017) or retinopathy, whereas one or both of these complications appeared in 8 of the 14 who had at least one high prorenin value. The plasma prorenin value was significantly higher in these eight patients at least 18 months before a complication was found.

CONCLUSIONS

Increased plasma prorenin activity identifies a group of young patients with diabetes who are at high risk for retinopathy or nephropathy.

Growth hormone response to growth hormone releasing hormone in depression and schizophrenia

Growth hormone releasing hormone, a 44-amino acid peptide (GHRH-44), was administered (1 micrograms/kg i.v.) to 6 normal controls, 10 schizophrenic subjects, and 7 depressed subjects. A significantly lower growth hormone (GH) response was found in the schizophrenic and depressed groups. Two molecular forms of GH, 22K GH and 20K GH, were also measured but did not further differentiate the three groups of subjects.

Malignant transformation of human fibroblasts by a transfected N-ras oncogene

The only ras oncogene as yet identified in cells from human fibrosarcomas is N-ras, but the relationship between N-ras oncogene expression and the malignant state of these cell lines is not known. To determine if expression of an N-ras oncogene causes human cells to become malignant, we transfected the N-ras oncogene from human leukemia cell line 8402, cloned into a high expression vector pSV N-ras, into MSU-1.1 cells, a nontumorigenic, infinite life span fibroblast cell strain with a normal morphology and a stable near-diploid karyotype. The transformants formed distinct foci composed of morphologically transformed cells. Cells from such foci expressed higher than normal levels of N-ras protein, exhibited growth factor independence, and formed large colonies in soft agar at a high frequency. Injection of progeny of these focus-derived cells s.c. into athymic mice resulted in progressively growing, invasive malignant tumors (round cell, spindle cell, or giant cell sarcomas) which reached a diameter of 6 mm in 3 to 4 weeks. Injection of focus-derived or tumor-derived cells i.v. resulted in tumors in various organs of the mice. The focus-derived cell strain tested, as well as the majority of the cells derived from the tumor it produced, exhibited the same near-diploid karyotype as the parental MSU-1.1 cells. Cells transfected with an N-ras oncogene that was expressed at a normal level formed only a single, indistinct focus, and cells from that focus were not malignant.

Bovine natural killer-like cell responses against cell lines expressing recombinant bovine herpesvirus type 1 glycoproteins

The murine retrovirus shuttle vector pZipNeo SV(X)1 was used to construct plasmids encoding the three major surface glycoproteins of bovine herpesvirus-1 (BHV-1). Each plasmid was transfected into D17, a canine osteosarcoma cell line sensitive to lysis by bovine NK-like cells when infected with BHV-1. After selection in G418 sulfate, cell lines expressing the recombinant gene products were sorted by flow microfluorimetry, radioimmunoprecipitated, and analyzed by SDS-PAGE for fidelity as compared to the native viral glycoproteins. Two of the three genetically engineered cell lines (gI and gIV) could successfully serve as targets to detect bovine NK-like cytolysis. These findings support and extend a previous study from our laboratory indicating a role for BHV-1 glycoproteins in the cytolytic response by bovine NK-like cells. Additionally, this study demonstrated that individual proteins are recognized by these effector cells, and that recombinant glycoproteins can direct cytolytic activity in the absence of host cell infection-associated proteins. This is the first known report of Ag directed cytotoxicity by bovine null (non-B, non-T) cells.

Bovine natural killer-like cell responses against cell lines expressing recombinant bovine herpesvirus type 1 glycoproteins

The murine retrovirus shuttle vector pZipNeo SV(X)1 was used to construct plasmids encoding the three major surface glycoproteins of bovine herpesvirus-1 (BHV-1). Each plasmid was transfected into D17, a canine osteosarcoma cell line sensitive to lysis by bovine NK-like cells when infected with BHV-1. After selection in G418 sulfate, cell lines expressing the recombinant gene products were sorted by flow microfluorimetry, radioimmunoprecipitated, and analyzed by SDS-PAGE for fidelity as compared to the native viral glycoproteins. Two of the three genetically engineered cell lines (gI and gIV) could successfully serve as targets to detect bovine NK-like cytolysis. These findings support and extend a previous study from our laboratory indicating a role for BHV-1 glycoproteins in the cytolytic response by bovine NK-like cells. Additionally, this study demonstrated that individual proteins are recognized by these effector cells, and that recombinant glycoproteins can direct cytolytic activity in the absence of host cell infection-associated proteins. This is the first known report of Ag directed cytotoxicity by bovine null (non-B, non-T) cells.