Enhancement of inositol phospholipid metabolism and activation of protein kinase C in ras-transformed rat fibroblasts

The inositol phospholipid metabolism is one of the main pathways of signal transduction in cells. We measured the activities of its key enzymes in v-Ha-ras-transformed 208F rat fibroblasts. In the ras-transformed clones, incorporation of [32P]Pi into intermediates of the inositol phospholipid metabolism was stimulated. The activities of phosphatidylinositol and phosphatidylinositol-4-phosphate kinases in the transformed clones were about 35-50% more than in untransformed cells, indicating increased inositol phospholipid metabolism. However, the activity of diacylglycerol kinase in their membrane fraction was 25-35% less than that of untransformed cells, although the total diacylglycerol kinase activity did not change. The imbalance of these kinases could constitute one of the main reasons leading to the increased level of inositol phosphates and the accumulation of diacylglycerol to 2-2.2 times that in control 208F cells. Phosphatidylinositol-4,5-bisphosphate-phospholipase C activity did not change on the transformation when assayed under various conditions. The increased level of diacylglycerol caused intracellular translocation, activation, and down-regulation of protein kinase C changes which may be one of the essential events in transformation by the v-Ha-ras gene.

The role of adenylate cyclase in relaxation of brain arteries: studies with forskolin

The natural product, forskolin, which stimulates adenylate cyclase by a direct, non-receptor-mediated mechanism, was studied for its effect on the tension of isolated brain arteries and adenylate cyclase activity of cerebral arteries. Helical strips of bovine and porcine basilar arteries and bovine middle cerebral arteries, which had been precontracted with prostaglandin F2 alpha (PGF2 alpha) or KCl, relaxed potently to administration of forskolin with ED50 values, ranging from 22 to 69 nM. Incubation of forskolin with a broken cell preparation of bovine cerebral arteries resulted in an efficacious stimulation of adenylate cyclase, approximating 5 times basal activity at a forskolin concentration of 1 microM. The metal salts nickel chloride and manganese chloride decreased the potency of vasorelaxation by vasoactive intestinal peptide (VIP), which stimulates adenylate cyclase via the VIP receptor. In contrast, nickel chloride had little effect on vasorelaxation by forskolin. The endogenous nucleoside, adenosine, which acts via the adenosine receptor and adenylate cyclase, relaxed bovine basilar and middle cerebral arteries with ED50 values ranging from 0.26 to 0.94 microM. The data presented support a role for adenylate cyclase in mediating vasodilation of brain blood vessels.

A transcriptionally defective long terminal repeat within an endogenous copy of mouse mammary tumor virus proviral DNA

Mouse mammary tumor virus proviral DNA is endogenous to most inbred strains of mice but in many strains is not transcriptionally active. This inactivity may be due to defects in the proviruses themselves or to position effects mediated by DNA sequences flanking the proviral units. The transcriptional competence of long terminal repeats (LTRs) derived from endogenous proviral DNA at genetic loci Mtv-8, Mtv-9, and Mtv-17 of the C57BL/6 mouse strain was examined with a transient transfection assay in which gene expression was monitored by expression of chloramphenicol acetyltransferase. LTRs from Mtv-8 and Mtv-9 were able to direct glucocorticoid-induced chloramphenicol acetyltransferase expression in this assay, while the LTR from Mtv-17 was only about 5% as effective. Analysis of chimeric LTRs indicated that the glucocorticoid-inducible transcriptional enhancer element within the Mtv-17 LTR is active when linked to a functional promoter from Mtv-8, whereas the promoter from Mtv-17 is defective in directing hormone-induced gene expression, even when linked to the Mtv-8 glucocorticoid-responsive enhancer. The DNA sequence of transcriptional control regions of the LTRs of all three endogenous proviral units was determined; this analysis revealed that the source of the defect in Mtv-17 is a single G-to-A transition at position-75 with respect to the site of transcription initiation that resides within the previously defined binding site for the transcription factor nuclear factor 1. Competition experiments with a gel electrophoresis mobility shift assay indicated that the affinity of nuclear factor 1 for DNA derived from Mtv-17 is significantly less than for comparable sequences derived from Mtv-8.

Mechanisms of partial renal infarct hypertension

Contributions of both the renin-angiotensin and immune systems to the aetiology of renal infarct hypertension were examined in Sprague-Dawley rats. Partial renal infarction was produced by ligating and sectioning two out of three branches of the left renal artery. The right kidney remained intact. Renal infarction resulted in rapid development of stable hypertension. One week following infarction, the plasma renin activity (PRA) increased more than threefold. However, PRA returned to control levels 4 weeks after infarction. Chronic immunosuppressive therapy with cyclophosphamide at most only attenuated the development of renal infarct hypertension associated with this transient renin elevation. However, cyclophosphamide prevented the later maintenance phase of the hypertension, and could also completely reverse established infarct hypertension. Activation of the renin-angiotensin system plays a role in the onset of partial renal infarct hypertension, but an intact immune system is required for maintenance of the hypertension. It is hypothesized that immunological reactions against renal tissue maintain renal infarct hypertension.

The effect of euglycemic hyperinsulinemia on cerebral cortical glucose metabolism in newborn beagles

There is a paucity of information on the significance of insulin on neonatal cerebral glucose metabolism. The effect of insulin on neonatal cerebral glucose uptake and cerebral cortical metabolic intermediates was investigated with the euglycemic hyperinsulinemic clamp in unanesthetized beagles during the first day of life. Insulin was infused at various rates to sustain an elevated steady state plasma insulin concentration in individual pups. Furthermore, blood glucose and 2-deoxyglucose levels were also maintained ("clamped") in a steady state by infusion of glucose and 2-deoxy-[14C]-glucose. Mean (+/- SD) plasma insulin levels were 20 +/- 12 and 2971 +/- 3386 (33-14330) microU/ml in control and hyperinsulinemic pups. Blood glucose concentration was 4.43 +/- 2.64 mM during basal periods and 4.54 +/- 2.87 mM during the clamp period in study pups. Basal fasting glucose utilization in study pups was 43.9 +/- 24 mumol/kg/min and increased to 60.9 +/- 35.2 mumol/kg/min (p less than 0.001) during hyperinsulinemia. Immediately after the euglycemic hyperinsulinemic clamp or fasting in control pups, the cerebral cortex was frozen to the temperature of liquid nitrogen. No differences were noted for any cerebral cortical intermediate between the two pup groups. In addition, there was no relationship between the cerebral intermediates concentration when analyzed as a function of plasma insulin levels. The uptake of cerebral 2-deoxyglucose was analyzed as a function of plasma insulin concentration (120-6900 microU/ml). Brain tissue demonstrated a positive linear relationship for 2-deoxyglucose uptake as a function of plasma insulin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical management of soft tissue sarcomas, with an analysis of 313 cases

From 1964 to 1978, 313 patients, 192 males and 121 females, with soft tissue sarcoma underwent surgery in our hospital. All patients have been followed up for over 5 years. One hundred ninety patients (60.7%) had recurrence of the tumor after previous surgery. The tumor was located in the head in 55 cases, in the trunk in 136, and in the extremities in 122 cases. Regional lymph node metastases occurred in 23 patients (7.4%). Fibrosarcoma, neurofibrosarcoma, and rhabdomyosarcoma were the types most commonly encountered in this series. The 5-year survival rate, according to the extent of surgical resection for 117 patients with local resection, was 47.9%; for 75 patients with wide local resection, 62.7%; for 43 patients with amputation, 18.6%; and for 78 patients with local resection combined with irradiation, 48.7%. For the whole series, the 5- and 10-year survival rates were 47.6% and 35.8%, respectively. The 5-year survival rates of stages I, II, III, and IV (TNM classification) were 60%, 46.9%, 40%, and 22.2%, respectively.

Utility of polycation-treated filters for the assay of receptors for VIP

This study examined the utility of four polycationic agents for treating glass fibre filters used in the receptor binding assay for vasoactive intestinal peptide (VIP). Polyethylenimine (PEI), polybrene, protamine and methylated bovine serum albumin proved satisfactory in terms of low filter binding of free radioligand and retention of membrane-bound radioligand. Their performance was superior or comparable to untreated Millipore EGWP cellulose acetate filters which we had previously utilized but which are no longer manufactured. The results with polycations indicate the importance of ionic interactions between filter, biological membranes and radioligand in determining the performance of a filtration assay for radioligand-receptor binding. At a practical level, PEI has the disadvantage of potential toxicity. The satisfactory performance of the other polycations indicates that they provide safer alternatives to PEI for filtration assay of the VIP receptor and possibly receptors for other basic ligands.

Modified responsiveness of v-Ha-ras-transfected rat fibroblasts to growth factors and a tumor promoter

The correlation of the phenotypic changes of v-Ha-ras transfected cells with the expression of p21ras and the modified responses to growth factors and a tumor promoter were examined. Transfection of the v-Ha-ras gene together with the neomycin-resistance gene into 208F rat fibroblasts yielded transformed clones characterized by morphological changes, anchorage-independent growth, and tumorigenicity in nude mice. The degrees of these biological alterations were parallel with the expression of mRNA and protein of the ras gene. In ras-transformed cells, anchorage-independent growth was stimulated by epidermal growth factor (EGF), insulin, bombesin, and fibroblast growth factor, whereas in the parental 208F cells, anchorage-independent growth was observed only in the presence of EGF, and there were many fewer EGF-induced colonies than those in the ras-transformed clones. A tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA) also augmented anchorage-independent growth of ras-transformed cells and induced morphological changes in monolayer cultures without altering the expression of the ras gene or phosphorylation of the p21ras protein. Retinoic acid inhibited the TPA-induced anchorage-independent growth. These results showed a good correlation of the expression of p21ras with the phenotypic changes and the increased sensitivity of the p21ras-expressing cells to the stimulation of growth factors and tumor promoter.

The clinical pharmacology of vancomycin in seriously ill preterm infants

The first dose and steady state pharmacokinetics of vancomycin were studied in 16 seriously ill preterm infants (less than or equal to 34 wk gestational age) with documented Staphylococcus epidermidis infections. One infant was dropped from the study due to peripheral flushing occurring during administration of the first dose. Individual vancomycin doses ranged from 9.8 to 17.8 mg/kg and were infused intravenously over 15-37 min. Fifteen infants were studied after the first dose of vancomycin, whereas only 12 of these 15 were able to be studied under steady state conditions. Vancomycin half-life, steady-state volume of distribution, and body clearance averaged 6.0 h, 0.53 liter/kg, and 1.22 ml/min after the first dose and only slight differences were observed in these parameter estimates under steady state conditions. However, substantial accumulation of vancomycin in serum was observed with multiple dosing. Complete 8-h urine collections were possible in 12 of 15 premature infants after the first dose of vancomycin. Overall, 44.6% of the dose was recovered in the urine with a corresponding vancomycin renal ClR averaging 0.88 ml/min. Vancomycin body Cl correlated directly with renal ClR (r = 0.88, p less than 0.001) and body weight (r = 0.8, p less than 0.001). Vancomycin pharmacokinetic parameter estimates Vdss and Cl correlated directly with body weight, surface area, and postconceptional age. No significant relationships were observed between these parameter estimates and gestational age or postnatal age. Fourteen of 15 infants were treated successfully for their underlying infectious process. These data support the use of lower doses of vancomycin than previously recommended for the treatment of preterm infants.

VIP receptors in mesenteric and coronary arteries: a radioligand binding study

Using a biologically active radioligand, [Tyr(125I)10]VIP, we have identified and characterized receptors for vasoactive intestinal peptide (VIP) on membranes prepared from the rat superior mesenteric artery and bovine coronary arteries. Binding was specific, saturable, reversible and dependent on time and temperature. Scatchard analysis suggested the presence of a high and a low affinity binding site in each arterial system with the following binding constants: the rat mesenteric artery, KD = 0.22 +/- 0.02 and 13.6 +/- 7.8 nM (corresponding maximum number of binding sites, RO = 606 +/- 44 fmol/mg protein and 2.1 +/- 0.2 pmol/mg protein); bovine circumflex coronary artery, KD = 0.10 +/- 0.01 and 37.8 +/- 16.1 nM (corresponding RO = 369 +/- 65 fmol/mg protein and 2.0 +/- 0.7 pmol/mg protein); bovine left and right descending coronary arteries, KD = 0.12 +/- 0.03 and 21.3 +/- 6.4 nM (corresponding RO = 472 +/- 7 fmol/mg protein and 2.2 +/- 0.3 pmol/mg protein). The arterial VIP receptors did not recognize secretin, glucagon, apamin or bovine parathyroid hormone, and had reduced affinity for PHI, PHM and growth hormone releasing factors (GRF). These recognition properties were, by and large, similar to those seen in the bovine cerebral arteries although a between-species heterogeneity of recognition function could be deduced from the differences in the competitive binding of rat and bovine vascular VIP receptors with the corresponding species-specific GRFs.

The studies of malignant transformation of human epithelial cells induced by diethyl-nitrosamine (NDEA) in vitro

This is the first report on the diethylnitrosamine-induced malignant transformation of human epithelial cells derived from fetal kidney. The transformed cells have prolonged life span and aneuploid karyotypes. They also form anchorage independent colonies in soft agar. With additional one or two NDEA treatments, these cells could elicit poorly differentiated carcinomas in immunosuppressed new-born rats. This experiment indicates that the human fetal kidney cells seem to be a good material for studying the mechanisms of carcinogenesis of human epithelial cell.

Malignant transformation of human fetal lung fibroblasts induced by nitrosamine compounds in vitro

This report, for the first time, demonstrates that diethyl-nitrosamine (NDEA) and a new nitrosamine compound-N-1-methylacetonyl-N-3-methylbutyl-nitrosamine (MAMBNA), which are suspicious carcinogens of esophageal cancer (EC) in Linxian, Henan Province, are able to cause the malignant transformation (altered morphology, extended life span, anchorage independent growth, invasiveness, tumorigenicity, etc.) of normal diploid fibroblasts derived from human fetal lung. Besides, the preselection for clonogenic cells, which seem to be more readily to be transformed, in soft agar before carcinogen treatment, could be considered as one of the useful ways in establishment of a model system of malignant transformation of human fibroblasts in vitro.

[Surgical management of soft tissue sarcoma]

From 1964 to 1978, 313 patients with soft tissue sarcoma were treated in our hospital by resection and followed over 5 years. 192 patients were males and 121 were females. The sex ratio was 1.5:1. In the 190 cases who developed postoperative recurrence, 55 were in the head and neck, 136 in the trunk and 122 in the limbs and 23 (7.4%) as metastasis in the lymph nodes. By pathology, the common types were fibrosarcoma (86 cases), neurofibrosarcoma (66 cases) and rhabdomyosarcoma (32 cases). All the 313 patients were treated by resection, the overall 5 and 10 year survival rates were 47.6% and 35.8%. The 5 year survival rate was 47.9% in the 117 patients treated by local resection, 62.7% in the 75 by extensive resection, 18.6% in the 43 by amputation and 48.7% in the 78 by combination of resection and irradiation. According to the UICC TNM staging system, the 5 year survival was 60% in stage I, 46.9% in stage II, 40% in stage III and 22.2% in stage IV. In this series, discussion of the treatment modalities and prognosis factors in emphasized.

Uptake of lung surfactant subfractions into lamellar bodies of adult rabbit lungs

The goals of this investigation were to determine whether subfractions of alveolar surfactant that have different physical and biochemical properties are preferentially taken up from the alveolar air space into lamellar bodies and to correlate the magnitude of the uptake with the properties of the fractions. Radiolabeled subfractions were obtained by differential centrifugation of lavage fluid from rabbits that had been intravenously injected with radioactive palmitate. The subfractions were P (pellet) 3 (1,000 g, 20 min), P4 (60,000 g, 60 min), P5 (100,000 g, 16 h). Subfractions were instilled into the lungs of anesthetized spontaneously breathing adult rabbits, and lavage and lamellar body fractions were isolated at later times. P3 and P4 were taken up to a larger extent than was P5 or liposomes prepared from a P4 lipid extract. The fractions that were preferentially taken up (P3 and P4) contained surfactant apoprotein (APO) 36, tubular myelin, multilamellar vesicles, and were rapidly adsorbed to an air-water interface. P3 also contained APO 10. These results demonstrate that different forms of surfactant are recycled at different rates and suggest that there is specificity in the recycling process.

Characterization of functional receptors for vasoactive intestinal peptide in bovine cerebral arteries

This study reports the characterization of receptors for vasoactive intestinal peptide (VIP) on membranes prepared from bovine cerebral arteries. By use of HPLC we prepared two purified monoiodinated VIP radioligands with nearly equivalent cerebral vasorelaxant potency as native VIP, [Tyr(125I)10 )VIP and [Tyr(125I)22]VIP. The former resulted in a higher proportion of specific binding to arterial membranes than the latter and was therefore thought to be the superior radioligand for receptor characterization. The binding of [Tyr(125I)10]VIP to cerebral arterial membranes was saturable, specific, reversible, and dependent on time and temperature. Scatchard analysis suggested the presence of a high- and a low-affinity binding site with KD values of 0.2 and 11 nM and receptor concentrations of 79 and 737 fmol/mg of protein, respectively. The dose-response curves for binding to the VIP receptor by the VIP-homologous peptides PHI, PHM, and rat growth hormone-releasing factor (GRF) were very similar to their dose-response curves for relaxation of cerebral arteries. The order of potency was VIP greater than PHM greater than PHI greater than rat GRF. It is suggested that the characteristics of the vascular VIP binding sites and the close correlation between the binding and vasorelaxant properties of VIP and its related peptides argue for the vascular binding sites being functional receptors for VIP.

Cerebral vascular adenylate cyclase: evidence for coupling to receptors for vasoactive intestinal peptide and parathyroid hormone

We have studied the responsiveness of vascular adenylate cyclase to vasoactive intestinal peptide (VIP) and parathyroid hormone (PTH) using preparations of cerebral microvessels and arteries. Cerebral microvessels obtained from rats, guinea-pigs, cattle, and pigs all responded potently to bovine (b) PTH-(1-34), whereas considerable between-species variability was observed in the responsiveness to VIP. The homologous peptide to VIP, PHI (porcine heptacosapeptide), stimulated adenylate cyclase in both rat microvessels and a broken-cell preparation of bovine arteries. The ED50 values for activation of bovine arterial adenylate cyclase by VIP, PHI, and bPTH-(1-34) were 6.9 nM, 10 nM, and 100 nM, respectively, with the following order of efficacy: VIP = PHI greater than bPTH-(1-34). The other related peptides, hpGRF (human pancreatic growth hormone releasing factor), secretin, and glucagon, and the fragment VIP-(10-28) were inactive. The PTH antagonist, [Nle8, Nle18, Tyr34]bPTH-(3-34) amide, inhibited bPTH-(1-34) activation of vascular adenylate cyclase but did not affect activation by VIP using either microvessels or arteries. VIP or PHI demonstrated an additive effect with bPTH-(1-34) on vascular adenylate cyclase activity. However, the effects of VIP and PHI were nonadditive with each other. These data suggest that VIP and bPTH-(1-34) activate cerebral vascular adenylate cyclase by interacting with pharmacologically distinct receptors, whereas PHI and VIP likely interact with a common receptor.

Studies on mechanism of entry of EB virus into non-B lymphocytes. Establishment of an EB virus-producing human-tupaia hybrid cell line TuH18

With the use of the EB virus-producing lymphoblastoid cell line H18, an attempt was made to infect the monolayer cell culture of nasopharyngeal tissue from the normal tupaia, and an EB virus-producing, human-tupaia hybrid cell line was established. The mechanism of entry of EB virus into cells other than B lymphocytes is discussed in this paper.

Effects of vitamin A-deprivation on hamster tracheal epithelium. A quantitative morphologic study

The effects of vitamin A-deprivation on the tracheal epithelium were studied in 35-day old hamsters that had been raised since birth on a vitamin A-deficient diet. Colchicine and 3HTdR were given 6 hours before death and the proliferative activities of basal cells and mucous cells were quantified separately by 3HTdR labeling indices and mitotic rates. Vitamin A-deprivation decreased replication of basal cells and mucous cells in tracheal epithelium which showed minimal morphologic change. The mitotic rates and labeling indices were reduced 3 to 4-fold in basal cells and 14-fold in mucous cells (analyzed as percent of total number of each cell type) compared with controls. Thus, replication of mucous cells was more inhibited by lack of vitamin A, than replication of basal cells. The disparate hypoplasia of basal cells and mucous cells in epithelium showing minimal change, resulted in a relative increase in the proportion of basal cells and a relative decrease in the proportion of mucous cells, which could be erroneously interpreted as "basal cell hyperplasia". Proportions of preciliated and ciliated cells were also decreased compared to controls. At foci of stratification and epidermoid metaplasia, cell replication rates were increased over controls and more than 70% of all mitotic activity was associated with "non-basal" cells. Genesis of these lesions was coincident with cell death and cell loss. The histogenesis of stratification and epidermoid metaplasia was characterized. Morphological evidence indicated that these lesions were closely related histogenetically and were composed, for the most part, of altered mucous cells which expressed dual phenotypes i.e. keratinization and mucus synthesis.

Restoration of mucociliary tracheal epithelium following deprivation of vitamin A. A quantitative morphologic study

In order to learn more about the respective roles played by basal cells and mucous cells in the maintenance of tracheal mucociliary epithelium, cell kinetics and epithelial cell morphology were characterized over a 7-day period, during which dietary vitamin A was restored to previously deprived hamsters. Hamsters were reared from birth to 35 days of age on vitamin A-replete or deficient diets. Deprived hamsters were made replete by 5 mg vitamin A-acetate orally, plus a vitamin A-replete diet. Colchicine and 3HTdR were given 6 h before death. The numbers of basal cells, mucous cells, preciliated cells and ciliated cells, and mitotic rates (MR) and labeling indices (LI) of basal cells and mucous cells, were quantified in glycol methacrylate sections stained with PAS-lead hematoxylin. Vitamin A-deprivation decreased replication of basal cells and mucous cells in tracheal epithelium which showed minimal morphological change. The proportion of basal cells was increased and proportions of mucous, preciliated and ciliated cells were decreased. Following restoration of vitamin A to the diet, the basal cell MR remained below control level throughout the experimental period, but the mucous cell MR started to rise on day 2-replete, and on day 3-replete and thereafter the mucous cell MR was within the control range. Basal cell and mucous cell LI's showed similar trends. Preciliated cells were reduced or absent in vitamin A-deprived epithelium. Their number had risen by day 3-replete and thereafter they were generated within the control range. These cells matured into ciliated cells. By day 4-replete, the proportion of basal cells had decreased markedly and the proportions of mucous cells, and preciliated plus ciliated cells had increased, so that at this time cellular proportions were within or near control values. This trend continued so that by day 7-replete, a nearly normal mucociliary epithelium was restored. The results show that vitamin A-levels modulate replication rates of basal cells and mucous cells and indicate that mitotic division of mucous cells is a prerequisite for the genesis of preciliated cells and new mucous cells and for restoration of the mucociliary epithelium following deprivation of vitamin A in the diet.

Relaxation of bovine, porcine and human brain arteries by parathyroid hormone

We have studied the relaxant effect of bovine parathyroid hormone (bPTH) on helical strips of branches of bovine and human middle cerebral arteries and bovine and porcine basilar arteries. All arteries were studied after contraction with prostaglandin (PG) F2 alpha or KCl. In the case of all arteries contracted with PGF2 alpha, the ED50 of PTH vasorelaxation related to maximal vasorelaxation induced by papaverine ranged from 9 to 14 nM for bPTH-(1-34) and 100 to 220 ng/ml for native bPTH-(1-84). The PTH inhibitor, [Nle8, Nle18, Tyr34]bPTH-(3-34) amide, attenuated the vasorelaxant effect of both bPTH-(1-34) and bPTH-(1-84). The vasorelaxant effects of PTH which we have observed in this study are consistent with the stimulatory effects of PTH on vascular adenylate cyclase which we had previously reported.

Effects of vasoactive intestinal polypeptide, monoamines, prostaglandins, and 2-chloroadenosine on adenylate cyclase in rat cerebral microvessels

Adenylate cyclase in microvessels isolated from rat cerebral cortex was stimulated by guanine nucleotides, catecholamines, prostaglandin E1, prostaglandin E2, and 2-chloroadenosine. Catecholamine stimulation was mediated by interaction with beta-adrenergic receptors. The order of relative potency was: isoproterenol greater than epinephrine greater than norepinephrine. Activation of microvessel adenylate cyclase by prostaglandins E1 and E2 as well as by 2-chloroadenosine was dose related. Twenty-two peptides were tested for possible effects on the microvessel adenylate cyclase. Only vasoactive intestinal polypeptide (VIP) was stimulatory. No inhibitory action was observed. Activation by VIP required guanosine triphosphate and was dose dependent from 10 nM to 1 microM (ED50 = 0.1 microM). At 30 degrees C, stimulation of adenylate cyclase by the peptide increased linearly with time for up to 15 min. The effect of VIP was not inhibited by phentolamine or propranolol, suggesting that its action was not elicited by interaction with alpha- or beta-adrenergic receptors. Activation achieved by VIP and isoproterenol, prostaglandin E1, or 2-chloroadenosine was the sum of the individual stimulations, suggesting that receptors for VIP were distinct from those for isoproterenol, prostaglandin E1, and 2-chloroadenosine.

Parathyroid hormone stimulates adenylate cyclase in rat cerebral microvessels

We have studied the effect of parathyroid hormone (PTH) on adenylate cyclase of microvessels isolated from rat cerebral cortex. Native bovine (b) PTH-(1-84), the synthetic amino-terminal fragment bPTH-(1-34) and the synthetic analog [Nle8,Nle18,Tyr34]-bPTH- (1-34) amide stimulated adenylate cyclase in a dose-dependent manner with apparent ED50 values of 16 nM, 6.3 nM and 15 nM respectively. The stimulation by bPTH was greatly enhanced by guanosine triphosphate. The PTH antagonist, [Nle8,Nle18,Tyr34]-bPTH-(3-34) amide inhibited the action of bPTH-(1-84) and bPTH-(1-34). In summary, PTH stimulated adenylate cyclase in rat cerebral microvessels in a very similar manner to its stimulation in the renal cortex.

An evaluation of falls, syncope, and dizziness by prolonged ambulatory cardiographic monitoring in a geriatric institutional setting

Fifty-nine patients living in a geriatric residential setting underwent prolonged ambulatory cardiographic monitoring with the Holter monitor (AHM) as part of an investigation of falls, dizziness, and syncope. In 16 instances, cardiac arrhythmias were a contributing factor; in 12, the diagnostic AHM recordings were associated with unrevealing standard electrocardiographic (ECG) tracings. In 12 patients who had fallen, cardiac arrhythmias played a contributing role, but in only two of these cases was the ECG diagnostic. The value of the AHM for use in managing elderly patients, whose cardiac complaints may be vague, and especially in managing those who have sustained falls, is emphasized.

Diet and vitamin nutrition of the high esophageal cancer risk population in Linxian, China

In order to examine the nutritional status of the population of Linxian (in Henan, China) known to be at high risk for esophageal cancer (EC), we analyzed blood samples and conducted 3-day dietary surveys on 3 groups of normal adults, age 40-50, from Henan province. Two groups were from Linxian, where the EC mortality rate is about 138/100,000 (Group C, consisting of volunteers with a family history of EC, and Group NC, consisting of those who did not have a family history of EC). The third group, Group F, was from Fanxian, where the EC mortality rate is about 24/100,000. The average plasma retinol level was found to be about 0.27 micrograms/ml in all 3 groups; about 13%-20% of the individuals had a level less than 0.2 micrograms/ml. The average plasma carotene level of all 3 groups appeared to be adequate, ranging from 0.5-1.0 micrograms/ml. About 23% of the subjects in both Groups C and NC had low (less than 2 micrograms/ml) plasma ascorbate levels; in Group F, 16% had low ascorbate levels. Less than 12% of the individuals in each of the 3 groups had erythrocyte glutathione reductase activation coefficients less than 1.2, indicating a widely occurring riboflavin deficiency. Consumption of alcoholic beverages was not found to be a contributing factor to EC. The results of the present study reveal a deficiency of vitamins in the study populations, but do not indicate that the average nutritional status of the volunteers in Group C was worse than that of Groups NC and F with regard to vitamin A, ascorbate, and riboflavin.

Cognitive style and lateral eye movements

The lateral eye movement paradigm was employed to test the hypothesis that narrow categorizers, who are believed to be more analytic in information processing, make characteristic use of the left hemisphere, while broad categorizers, being more holistic, depend more on the right hemisphere. Data for narrow categorizers confirmed the hypothesis in that they tended to produce a majority of right shifts. Results from broad categorizers turned out to be less clear, although there was a tendency in the direction of left eye shift. Additionally, narrow categorizers made significantly more total LEMs than did broad categorizers. The results are discussed in terms of cerebral specialization underlying cognitive style.

Application of Linear and Nonlinear Graphs in Structural Synthesis of Kinematic Chains

Using graph theory and Polya’s theory of counting, the present paper performs structural synthesis and analysis of planar and three-dimensional kinematic chains. The Section 2 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of planar kinematic chains with kinematic elements such as revolute pairs, cam pairs, springs, belt-pulley, piston-cylinder, and gears. The theory developed is applied to enumerate eight-link kinematic chains with these kinematic elements. The Section 3 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of multi-loop spatial kinematic chains with higher and lower kinematic pairs. The theory developed is applied to enumerate all possible two-loop kinematic chains with or without general constraints.