[Brain dialysis--a new technique for determining the release of neurotransmitters and neuropeptides]

Brain dialysis, also called microdialysis, is a new technique based on the push-pull cannula. It can be used for continuously perfusing and collecting perfusate of certain brain areas in freely moving animals. Coupled with high performance liquid chromatography (HPLC) and radioimmunoassay (RIA), brain dialysis is allowed to determine the extracellular changes of many neurotransmitters in the brain, such as acetylcholine, noradrenaline, dopamine, 5-HT and their metabolites, free amino acids, small peptides, phosphoethanolamine, vitamins, various ions and so on.

[Experimental study of coral implantation in repair of skull bone defect in rabbit: histomorphometry of bone]

In order to evaluate coral as a bone graft substitute in repair of bone defect, particulates of coral were implanted into skull bone defect of rabbit, 1.5 cm in diameter. Hydroxyapatite and blank were taken as controls. The rabbits were sacrificed at the second, fourth, eighth and twelveth weeks after the operation. The specimens were taken and performed histological examination and histomorphometry observation. Results were as follows: at the second week many multinucleus giant cells infiltrated. As time elapsed, the coral were progressively degenerated and new bone was formed to fill the defect. Up to the twelveth week, the coral degenerated completely and new bone formed in the center of the defect. Percentage of new bone was in defect was 36.9%. Compared with the controls, there were significant differences (P < 0.01). It was suggested that coral had good osteoconductility. Howevel, coral underwent rapid degeneration, it might result in inconplete repair of bone defect.

Enhanced cyclooxygenase-2 gene expression in alcoholic liver disease in the rat

BACKGROUND & AIMS

Inflammatory stimuli and lipid peroxidation up-regulate cyclooxygenase (COX)-2. This study evaluated the relationship between inflammatory mediators, COX expression, and pathological changes in experimental alcoholic liver disease.

METHODS

Rats (5 per group) were fed ethanol and a diet containing saturated fat, corn oil, or fish oil by intragastric infusion. Dextrose isocalorically replaced ethanol in controls. In the first set of experiments, whole livers were analyzed. In the second set of experiments, Kupffer cells, endothelial cells, and hepatocytes were isolated from rats in each group. Pathological analyses and measurements of lipid peroxidation, tumor necrosis factor (TNF)-alpha, COX-1 and COX-2 messenger RNA (mRNA), endotoxin, and liver and plasma thromboxane were performed.

RESULTS

Increased expression of COX-2 mRNA was detected in the livers of rats showing necroinflammatory changes. The Kupffer cell was the cell primarily responsible for the increase in COX-2 mRNA level. Increased expression of COX-2 was associated with increased levels of endotoxin, TNF-alpha mRNA, lipid peroxidation, and synthesis of thromboxane. COX-1 mRNA was decreased in Kupffer cells in rats with the most severe liver injury.

CONCLUSIONS

Up-regulation of COX-2 in alcoholic liver injury occurred in the presence of proinflammatory stimuli and resulted in increased synthesis of inflammatory and vasoactive eicosanoids. Down-regulation of COX-1 may result in decreased synthesis of cytoprotective eicosanoids and additionally exacerbate liver injury.

Mechanisms of positive inotropic action of flosequinan, hydralazine, and milrinone on mammalian myocardium

Flosequinan is an arterial and venous dilator that also has a positive inotropic effect at relatively higher doses. The purpose of this study was to determine the mechanism of this positive inotropic effect in ferret papillary muscles loaded with the Ca2+ indicator, aequorin. Over the range of doses from 10(-6) to 10(-3) M, flosequinan produced a 61 +/- 9% increase in peak tension that was accompanied by a corresponding increase in [Ca2+]i. This positive inotropic effect was not selectively blocked by addition to the perfusate of procaine 0.6 microM, tetrodotoxin 10(-6) M or by verapamil, 5 x 10(-8) M. In contrast, the positive inotropic effect of flosequinan, but not milrinone or hydralazine, was potentiated by prior addition of ouabain 3 nM to enhance intracellular Ca2+ via reduction of the Na+/Ca2+ exchange. Moreover, antagonists of Na+/Ca2+ exchange, including cadmium 10 microM, amiloride 600 microM and choline substitution for 1/3 Na+ in the perfusate, blocked the response to flosequinan but not hydralazine or milrinone. These results indicate that flosequinan produces a positive inotropic effect by reduction of Na+/Ca2+ exchange in mammalian myocardium. Moreover, flosequinan has the potential to interact synergistically with other positive inotropic agents such as digoxin that affect Na+/Ca2+ exchange by direct or indirect actions.

Acute and chronic cocaine exposure can produce myocardial ischemia and infarction in Yucatan swine

The purpose of this study was to determine whether the acute and chronic administration of cocaine could induce myocardial infarction. Twenty-five minipigs were studied before and 4 months after balloon angioplasty of the left anterior descending artery (LAD) and balloon denudation of the left circumflex artery (LCx). Minipigs received cocaine in the initial and in the 4-month study (0.1, 0.5, and 3 mg/kg i.v.). Minipigs were randomized to group I (high-cholesterol diet + daily cocaine; 500 mg i.m.; n = 8), group II (high-cholesterol diet + no i.v. cocaine; n = 5), group III (chow diet + daily cocaine; 500 mg i.m.; n = 6), group IV (chow diet + no i.v. or i.m. cocaine; n = 6). In vivo, coronary flow significantly decreased and vascular resistance significantly increased after the administration of cocaine. Histamine significantly decreased the luminal diameters (LAD and LCx) in groups I, II and III. There were a total of five acute and 16 chronic infarctions among the three groups that received either short- or long-term cocaine; however, no infarct occurred in group IV. The combination of daily cocaine abuse with a cholesterol-rich diet enhanced coronary vasoreactivity in vivo and in vitro. We conclude that long-term or sporadic cocaine abuse can induce myocardial infarction.

Efficient adenovirus-mediated ectopic gene expression of human lipoprotein lipase in human hepatic (HepG2) cells

Gene therapy to deliver and express a corrective lipoprotein lipase (LPL) gene may improve the lipid profile and reduce the morbidity and potential atherogenic risk from hypertriglyceridemia and dyslipoproteinemia in patients with complete or partial LPL deficiency. We have used an E1-/E3- adenoviral vector, with an RSV-driven human LPL cDNA expression cassette (Ad-RSV-LPL), to achieve high ectopic LPL gene expression in the human hepatoma cell line HepG2, an accepted hepatocellular model of lipoprotein metabolism. Ad-RSV-LPL transduction of HepG2 cells with a multiplicity of infection (moi) between 12.5 and 100 yielded dose-dependent increments in LPL mass and activity. Peak levels of LPL protein of 2,032.1 +/- 274.5 ng/10(5) cells per ml (mol 100) correlated with increased activity of 92.7 +/- 22.6 mU/10(5) cells per ml relative to negligible LPL levels in Ad-RSV-LacZ (beta-galactosidase) controls. Exogenous LPL expression over a 5-day period peaked at day 3. Susceptibility to inhibition by 1 M NaCl and an anti-LPL monoclonal antibody confirmed that lipase activity was indeed derived from human LPL. Hydrolysis, by LPL-overexpressing HepG2 cells, of TG carried in very-low-density lipoprotein (VLDL) showed that greater than 50% of the triglycerides (TG) disappeared after 4 hr of incubation. These results were compatible with FPLC evidence of a marked reduction in VLDL-TG. These results provide strong in vitro evidence that adenoviral-mediated ectopic expression of the human LPL gene could render hepatic cells capable of VLDL catabolism and thus support the possibility for in vivo adenoviral vector-mediated liver-targeted LPL gene therapy.

Thromboxane inhibitors attenuate pathological changes in alcoholic liver disease in the rat

BACKGROUND & AIMS

Thromboxane levels correlate with severity of liver injury in rats given alcohol. The aim of this study was to evaluate the effect of thromboxane inhibitors on pathological changes in experimental alcoholic liver disease.

METHODS

Male Wistar rats were given a liquid diet and ethanol intragastrically for 1 month. The thromboxane inhibitors tested were a thromboxane receptor antagonist (TXRA) and a thromboxane synthase inhibitor (TXSI). Pathological changes, liver and plasma thromboxane levels, 6-ketoprostaglandin F1 alpha levels, lipid peroxidation, and messenger RNA levels for tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF) beta were evaluated.

RESULTS

Treatment with thromboxane inhibitors prevented necrosis and inflammation. In the TXSI-treated group, fatty liver was also decreased. Ethanol administration led to a 3-4-fold increase in liver thromboxane levels; a reduction in thromboxane levels and lipid peroxidation was seen in the TXSI group. In all treatment groups, TNF-alpha and TGF-beta messenger RNA levels were decreased.

CONCLUSIONS

The prevention of necroinflammatory changes in thromboxane-treated groups is related to a decrease in TNF-alpha levels. Inhibition of TGF-beta expression may also prevent fibrosis in ethanol-treated rats.

[Analysis of 822 infants with limb reduction defect in China]

This work is aimed at the basic condition of infants with limb reduction defect (LRD) in China. 822 cases of LRD occurring among 1,243,284 live and stillbirths of 28 or more gestation weeks in China from Oct. 1986 to Sept. 1987 were analysed. The overall prevalence of LRD was 6.6 per 10,000 ranging from 14.4 per 10,000 to 3.6 per 10,000. No sex difference was observed. The prevalence of LRD in infants with low birthweight was significantly higher than that in infants with normal birthweight (P < 0.001). Also the prevalence of LRD in rural area was higher than that in urban area (P < 0.001). Four-limb involvement was most common. The cases with only upper limb involvement (278/451, 61.6%) were significantly more prevalent than those with only lower limb involvement (173/451, 38.4%, P < 0.001), but no difference was found between the left LRD and right LRD (P > 0.05), nor was a significant difference noted between single LRD and multiple LRD. 75.8% of the infants with LRD had defects in other systems.

Increased renal tubular expression of transforming growth factor beta in human allografts correlates with cyclosporine toxicity

Cyclosporine A (CsA) is a potent immunosuppressive drug that inhibits the transcription of several proinflammatory cytokines including interleukin-2. In contrast, CsA stimulates transcription of the pleuripotent cytokine, transforming growth factor-beta (TGF beta). Since the effect of CsA in transplant recipients is unpredictable, we examined whether tissue levels of TGF beta protein in renal allografts correlate with in vivo CsA responsiveness. Intra-allograft TGF beta protein content was assessed in renal biopsies by immunohistochemical means using the mouse anti-TGF beta monoclonal antibody (Mab), 1D11. We studied 68 specimens: 21 with acute CsA toxicity (ACT), 11 with acute tubular necrosis (ATN) and 36 with acute cellular rejection (ACR). Intensity of TGF beta immunostaining was evaluated in a blinded fashion using a scale from 0 to 3+. In biopsies with histological evidence of CsA toxicity, 77% demonstrated intense (2 to 3+) TGF beta immunostaining. TGF beta protein was detected in both proximal and distal tubules but was either absent or present in low levels within glomeruli and interstitium. In contrast, only one of the 11 biopsies with ATN had minimal staining (1+) for TGF beta. The remaining 10 biopsies with ATN were negative for TGF beta immunostaining. In biopsies with ACR, the levels of renal TGF beta were more variable with 36% showing intense (2 to 3+) staining and 64% having minimal or no (0 to 1+) tubular TGF beta. Within the first 18 months post-transplantation, patients with intense TGF beta staining and ACR underwent an average of 4.1 +/- 1.8 allograft biopsies and suffered 33% graft losses. During the same period of time, the patients with ACR and absent or low (0 to 1+) TGF beta levels underwent only 2.1 +/- 1.2 biopsies, maintained better late renal function and suffered 4% graft losses. In conclusion, we demonstrate that TGF beta protein levels in renal allografts correlate with CsA effect and differentiate ACT from ATN. In CsA treated patients who develop ACR, TGF beta levels predict the subsequent clinical course and graft function. Therefore, evaluating tissue levels of TGF beta may offer unique diagnostic and prognostic benefits in the care of patients receiving CsA based immunosuppression.

Model of a sub-main transition in phospholipid bilayers

A recently discovered submain phase transition in multi-lamellar bilayers of long-chain saturated diacyl phosphatidylcholines (Jørgensen, K. (1995) Biochim. Biophys. Acta 1240, 111-114) is discussed in terms of a theoretical molecular interaction model using computer simulation techniques. The model interprets the transition to be due to a decoupling of the acyl-chain melting from the melting of the pseudo-two-dimensional crystalline lattice of the P beta' phase. A two-stage melting process is predicted by the calculations suggesting that the sub-main transition involves a lattice melting whereas the acyl-chain melting takes place at a higher temperature at the main transition. The calculated heat contents of the two transitions as well as the chain-length dependence compare favorably with experimental data for multi-lamellar phosphatidylcholine lipid bilayers.

A frequently occurring mutation in the lipoprotein lipase gene (Asn291Ser) results in altered postprandial chylomicron triglyceride and retinyl palmitate response in normolipidemic carriers

An Asn291Ser mutation in exon 6 of the lipoprotein lipase gene (LPL) frequently occurs in Caucasians (2-4%) and results in a partial catalytic defect. Although this mutation may be associated with low HDL cholesterol and elevated triglyceride levels, some carriers are normolipidemic and may have LPL activity in the normal range in the fasting state. To assess in vivo the influence of dietary stress on the function of this mutation, we have performed oral fat load studies on three unrelated normolipidemic Asn291Ser carriers and compared these results to five healthy controls and to a subject with a clear 50% reduction in LPL activity compared with controls. The Asn291Ser carriers exhibited a more pronounced postprandial response compared with non-carriers as evidenced by higher chylomicron triglyceride (TG) and chylomicron retinyl palmitate peaks (P = 0.03 and P = 0.02, respectively). Significantly higher area under response curves were also seen for both chylomicron triglycerides (P = 0.02) and chylomicron retinyl palmitate (P = 0.01) when compared with non-carriers. These results provide further in vivo evidence for the functional effects of this common mutation despite normal fasting lipid levels. These data suggest that even though subjects with this mutation may be normolipidemic in the fasting state, environmental stress such as an oral fat load may unmask the catalytic defect and result in significant disturbances in postprandial chylomicron metabolism.

Common sequence variants of lipoprotein lipase: standardized studies of in vitro expression and catalytic function

We have assessed the functional activity of three common sequence variants of human lipoprotein lipase (LPL). Two of these, Asn291Ser and Asp9Asn arise from missense mutations while the third, Ser447Ter, derives from a nonsense mutation, truncating LPL by two residues. As previous in vitro studies have produced conflicting results, we have re-analyzed the catalytic function of these variants using the COS cell transfection system, under optimized and standardized experimental protocols. We found the Asn291Ser variant to manifest with a decrease in catalytic activity (57% of normal) due to a reduction in secretion and stability of the active homodimeric form. The Asp9Asn variant also showed a significant decrease in catalytic activity (85% of normal), but this was found to be due to a decreased rate of secretion only, as the homodimeric form was stable. The findings for these mutants contrasted with those of the Ser447Ter truncation variant which proved to be catalytically normal; this variant also manifested normal homodimer stability. The truncated variant did however, present with a higher total secreted mass level (131%) than control LPL. This was most likely due to enhanced secretion of the monomeric form. None of these mutations exhibited defects in binding affinity to cell surface proteoglycans. Each of these variants deviated significantly from normal as regards to their secreted activity or mass levels in the COS cell transfection system.

[Analysis of 106,272 cases of postterm pregnancy in China]

106272 cases of postterm pregnancy in 945 hospitals in China during the period from Oct. 1986 to Sept. 1987 were surveyed, the overall incidence rate was 85.48/1000. Provincially, the highest two rates were 127.36/1000 and 120.92/1000 in Jilin and Shandong provinces respectively, and the lowest two rates 53.98/1000 and 61.38/1000 in Xizang and Qinghai provinces respectively. The perinatal mortality was 27.90/1000 (corrected 12.49/1000). The incidence of macrosomia (89.50/1000) in postterm pregnancy was twice as much as that in term delivery. Postterm pregnancy was more frequent in pregnant women of 20-34 years old,and of 42 weeks' gestation. The incidence malformations in postterm pregnancy was 154.13 per ten thousand, in which the frequency of malformations associated with low birth weight was three times that associated with macrosomia.

Cholinergic stimulation modulates negative inotropic effect of cocaine on ferret ventricular myocardium

We tested the hypothesis that the negative inotropic effect (NIE) of cocaine is mediated, at least in part, by cholinergic stimulation and can be correlated with the degree of adenosine 3',5'-cyclic monophosphate (cAMP) dependency of the inotropic state. Cardiac myocytes were isolated from left ventricles of ferrets and loaded with the fluorescent Ca2+ indicator indo 1. Cells were placed in physiological solution containing 2.0 mM Ca2+ and stimulated at 0.5 Hz and 30 degrees C. Cocaine decreased peak cell shortening and peak intracellular Ca2+ in a concentration-dependent manner (10(-8)-10(-4) M). The concentration-response curve of cocaine was shifted significantly downward compared with those of lidocaine and procaine in the same range of concentrations. Atropine (10(-6) M) shifted the concentration-response curve of cocaine, but not those of lidocaine and procaine, rightward, with a pA2 value (7.66) similar to that obtained with carbachol (7.99). With prior addition of isoproterenol (ISO, 10(-8) M) or increased Ca2+ (4.0 mM) to increase cell shortening to the same degree (approximately 60%), cocaine and carbachol decreased contractility to a significantly greater extent in ISO-stimulated myocytes. To clarify whether these treatments changed responsiveness of the contractile elements to Ca2+, the effect of 2,3-butanedione monoxime, an agent that interferes with the interaction of myosin and actin, was tested with previous addition of ISO or increased Ca2+, and no differential effect occurred. Therefore, we postulate that 1) the NIE of cocaine on myocytes is caused by decreased Ca2+ availability; 2) this effect is due to specific stimulation of cholinergic receptors in addition to other direct myocardial (probably local anesthetic) effects; and 3) the NIE correlates with the level of cAMP dependence of the inotropic state.

Effects of formic acid hydrolysis on the quantitative analysis of radiation-induced DNA base damage products assayed by gas chromatography/mass spectrometry

Gas chromatography/mass spectrometry (GC/MS-SIM) is an excellent technique for performing both qualitative and quantitative analysis of DNA base damage products that are formed by exposure to ionizing radiation or by the interaction of intracellular DNA with activated oxygen species. This technique commonly uses a hot formic acid hydrolysis step to degrade the DNA to individual free bases. However, due to the harsh nature of this degradation procedure, the quantitation of DNA base damage products may be adversely affected. Consequently, we examined the effects of various formic acid hydrolysis procedures on the quantitation of a number of DNA base damage products and identified several factors that can influence this quantitation. These factors included (1) the inherent acid stabilities of both the lesions and the internal standards; (2) the hydrolysis temperature; (3) the source and grade of the formic acid; and (4) the sample mass during hydrolysis. Our data also suggested that the N,O-bis (trimethylsilyl)trifluoroacetamide (BSTFA) derivatization efficiency can be adversely affected, presumably by trace contaminants either in the formic acid or from the acid activated surface of the glass derivatization vials. Where adverse effects were noted, modifications were explored in an attempt to improve the quantitation of these DNA lesions. Although experimental steps could be taken to minimize the influence of these factors on the quantitation of some base damage products, no single procedure solved the quantitation problem for all base lesions. However, a significant improvement in the quantitation was achieved if the relative molecular response factor (RMRF) values for these lesions were generated with authentic DNA base damage products that had been treated exactly like the experimental samples.

Cocaine-induced microvascular vasoconstriction but differential systemic haemodynamic responses in Yucatan versus Yorkshire varieties of swine

1. Systemic and coronary haemodynamics were measured in 6 Yorkshire swine and 6 Yucatan miniature swine under isoflurane anaesthesia to investigate the influence of cocaine following its intravenous administration at 1, 3 and 7 mg kg-1. 2. Cocaine in Yorkshire swine decreased mean arterial pressure and rate pressure product (systolic pressure x heart rate), suggesting a cardiac depressant effect, whereas cocaine in Yucatan miniature swine increased these parameters, consistent with a hyperadrenergic state. 3. Cocaine in both Yorkshire swine and Yucatan miniature swine decreased coronary blood flow and coronary flow reserve, and increased coronary vascular resistance. 4. A modest generalized epicardial coronary artery constriction was observed by angiography, without evidence of focal spasm. 5. Our results confirm a marked vasoconstrictor effect of cocaine on the coronary arterial circulation, predominantly distal to the epicardial coronary arteries, but also indicate important differences in the systemic cardiovascular responses to the drug between two closely related strains of animals within the same species. Due to the similarities between the swine and human coronary arterial vasculature, we suggest that vasoconstriction in the coronary microcirculation may produce cardiac toxicity in man.

A frequently occurring mutation in the lipoprotein lipase gene (Asn291Ser) contributes to the expression of familial combined hyperlipidemia

We performed denaturing gradient gel electrophoresis (DGGE) of exons 4, 5, 6 and their exon-intron boundaries of the LPL-gene in 169 unrelated male patients suffering from familial combined hyperlipidemia (FCH). Twenty patients were found to carry a nucleotide substitution in exon 6. Sequence and PCR/digestion analysis revealed one common mutation (Asn291Ser) in all these cases. This mutation was talso present in 215 male controls, albeit at a lower frequency than in FCH patients (10/215 = 4.6% vs. 20/169 = 11.8%; p < 0.02). Analysis of lipid, lipoprotein and apolipoprotein levels demonstrated an association between the presence of this Asn291Ser substitution and decreased HDL-cholesterol (0.94 +/- 0.31 vs. 1.12 +/- 0.26 mmol/l; p < 0.04) in our controls. FCH patients carrying this mutation showed decreased HDL-cholesterol (0.75 +/- 0.16 vs. 0.95 +/- 0.36 mmol/l; p = 0.05) and increased triglyceride levels (5.96 +/- 4.12 vs. 3.48 +/- 1.78 mmol/l; p < 0.005) compared to non-carriers. The high triglyceride and low HDL-cholesterol phenotype in carriers of this substitution was most obvious when BMI exceeded 27 kg/m2. Our study of male FCH patients revealed the presence of a common mutation in the LPL-gene that is associated with lipoprotein abnormalities, indicating that defective LPL is at least one of the factors contributing to the FCH-phenotype.

[Analyses of the prevalences for neural tube defects and cleft lip and palate in China from 1988 to 1991]

This paper reports the monitoring results of two main categories of birth defects-neural tube defects (NTD) and cleft of lip and palate (CLP) in China during the period of continuous monitoring (1988-1991). The method of hospital-based monitoring was adopted for data collection. From Jan. 1988 to Dec. 1991, a total of 2,750,588 births were monitored, and 28,168 cases of congenital malformations were identified. The prevalence of total birth defects was 102.4 per 10,000. 6885 cases of NTD were identified during this period, the prevalence of NTD being 25.0 per 10,000. The prevalence of NTD varied geographically; it declined gradually from the north to the south of China with the highest rate of NTD in the Taihang Mountain Regions. A total of 4548 cases of CLP were identified, and the provincial prevalence of CLP varied from 11.2 to 25.7 per 10000 with a mean of 16.5 per 10000. The prevalence of NTDs varied seasonally with the peak in winter (January). The sex ratio of NTD was 0.59, the prevalences in female births (32.1 per 10,000) being higher than that in male births (17.4 per 10,000) (P < 0.01). The sex ratio of CLP was 1.33. A significant difference was noted between the sex ratio of cleft palate (0.80) and that of the total cleft lip (1.46) (P < 0.01). The prevalence of NTD in rural areas (44.3 per 10,000) was 3 times as high as that in urban areas (14.4 per 10,000), but no difference in occurrence of CLP was observed between the urban and rural areas (P > 0.05).

[Analysis of factors contributing to low birth weight in Sichuan Province. Cooperating Group for Birth Defects Monitoring]

Data on low birth weight and some potential factors were obtained from an epidemiologic investigation of 111,676 births in Sichuan province during the period from Oct. 1986 to Sep. 1987. There were 8177 (73.22%) cases of low birth weight and 516 (79.89%) dead cases of low birth weight. The results suggest that the occurrence of low birth weight is affected by maternal age, fetal number and living level in rural areas. The incidence of low birth weight delivered by women aged 35 and over is 100.94%; it is 331.53% for twins and 265.96% for triplets. The incidence of low birth weight in rural areas (94.91%) is higher than that in urban areas (59.44%).

Potent inhibition of viral fusion by the lipophosphoglycan of Leishmania donovani

Lipophosphoglycan (LPG) is an amphiphile produced by Leishmania. Its chemical structure consists of a hydrophilic flexible polymer of repeating PO4-6Gal beta 1-4Man alpha 1 units (on average 16 units) linked via a hexasaccharide core to a lyso-1-O-alkyl-P1 membrane anchor. In the study of viral fusion we report in this paper, we have introduced LPG into human erythrocyte ghost (HEG) membranes, with the purpose of understanding how the LPG-induced surface-structural changes may modulate the interactions between a viral envelope and the HEG membranes. We have found that LPG, when incorporated at very low concentrations into intact human erythrocyte membranes, strongly inhibits Sendai virus-induced hemolysis. When incorporated into HEGs, it reduces the binding of both Sendai and influenza viruses to HEGs; furthermore, it strongly inhibits the overall viral fusion to HEGs, being among the most potent known inhibitors. We have also shown that LPG stabilizes the bilayer structure of phosphatidylethanolamine against the formation of an inverted-hexagonal structure. We suggest that LPG may give rise to an effective "steric repulsion" between the viral and HEG membranes, thereby modulating some specific modes of interaction between viral-target membranes in the overall fusion process; LPG may also modulate the bending rigidity and the spontaneous curvature of the HEG membrane in the direction of making the destabilization and rearrangement of the underlying lipid bilayer more difficult.

Effects of cocaine on carotid vascular reactivity in swine after balloon vascular injury

BACKGROUND AND PURPOSE

The use of cocaine has been associated with stroke. To evaluate carotid vasospasm as a potential mechanism of cocaine-induced stroke, we studied 12 swine immediately and 10 weeks after angioplasty.

METHODS

We compared the short- and long-term vasoconstrictor responses of normal and injured arterial segments to nitroglycerin, histamine, and cocaine in vivo by carotid angiography. We also compared the isometric contractile force responses to different vasoactive substances in normal and injured vascular rings in vivo, and we tested the direct action of cocaine on both arterial segments.

RESULTS

In in vivo studies, immediately after angioplasty, luminal diameter in the control segment decreased by 30% with histamine 30 micrograms/kg and by 23% with cocaine 10 mg/kg (P < .001). In contrast, neither histamine nor cocaine produced vasoconstriction in the angioplasty segment. Thus, a transient loss of vasoconstriction occurred at the angioplasty site. Ten weeks later, histamine 30 micrograms/kg significantly (P < .001) decreased luminal diameter by 34% in the control and by 33% in the angioplasty segment; similarly, cocaine 10 mg/kg significantly (P < .001) decreased luminal diameter by 26% in the control and by 34% in the angioplasty segment. Thus, 10 weeks after angioplasty, the transitory loss of carotid vasoconstriction in response to histamine and cocaine reverted, and a moderate generalized vasoconstriction occurred in both segments without localized vasospasm. In vitro, the maximal isometric tension responses to KCl, acetylcholine, histamine, and phenylephrine were similar in vascular rings from normal and angioplasty segments. The median effective doses to histamine and phenylephrine were similar. In contrast, cocaine in concentrations from 10(-7) to 10(-3) mol/L failed to produce any isometric contraction in vitro.

CONCLUSIONS

Cocaine in vivo produced a generalized carotid vasoconstriction without evidence of localized vasospasm; since there was no response to cocaine in vitro, the in vivo effect was most likely mediated by neurohumoral factors rather than by a direct action of cocaine on vascular smooth muscle.

Cocaine-induced microvascular spasm in Yucatan miniature swine. In vivo and in vitro evidence of spasm

The purpose of the present study was to determine the maximal coronary flow reserve (CFR) before and after the administration of successive cocaine doses (0.1, 0.5, 3, and 7 mg/kg IV) for 2 minutes at 10-minute intervals in eight miniature swine. CFR was assessed by the administration of adenosine (0.03, 0.3, and 3 mg IC). Hemodynamic and flow measurements were performed 3 minutes after each dose. Coronary flow (CF) was measured with a Doppler-tipped wire in the proximal left anterior descending coronary artery (LAD). Also, microvessels were dissected, and vessel diameters were measured by a videoelectronic dimension analyzer. In vivo, LAD CF increased fourfold, CFR increased twofold, and coronary vascular resistance (CVR) decreased fourfold after the administration of adenosine. In contrast, LAD CF decreased threefold, CFR decreased onefold, and CVR increased sixfold 3 minutes after the administration of cocaine. Adenosine (3 mg) was repeated 4 minutes after the administration of cocaine, and LAD CF increased 1.4-fold, CVR increased 2.5-fold, and CFR decreased onefold. Thus, adenosine partially reversed the potent cocaine constrictor effect. In vitro, 10(-9) mol/L cocaine decreased the diameter of the coronary microvessels from 129 +/- 12 to 127 +/- 12 microns, and 10(-4) mol/L cocaine decreased coronary microvessel diameter to 114 +/- 15 microns (P < .05). In conclusion, cocaine in vivo decreases CFR, and consistent with the in vivo effect, cocaine in vitro produced constriction of vessels < 200 microns. These results indicate that cocaine can produce profound microvascular spasm. This may contribute to the ischemia/infarction reported in patients who abuse cocaine and who are subsequently found to have normal epicardial coronary arteries.

Cardiogenic shock induced by cocaine in swine with normal coronary arteries

OBJECTIVE

The aim was to test the hypothesis that acute intravenous cocaine administration can cause coronary microvascular constriction culminating in myocardial ischaemia and cardiogenic shock.

METHODS

Systemic haemodynamic variables and coronary blood flow were measured in 14 Yorkshire swine at baseline and following intravenous administration of 1, 3, and 10 mg.kg-1 of cocaine. Epicardial coronary artery diameter was measured from coronary arteriograms and coronary flow velocity was recorded with a Doppler flow wire.

RESULTS

Cocaine produced a decrease in mean arterial pressure (65%), cardiac output (80%), and stroke volume (80%), and an increase in pulmonary artery diastolic pressure (60%). Although coronary blood flow decreased by 70%, epicardial coronary cross sectional area decreased by only 37-45%. Pretreatment with prazosin did not abolish the decrease in coronary blood flow. After administration of 10 mg.kg-1 of cocaine, five of 14 animals developed myocardial ischaemia and cardiogenic shock, culminating in ventricular fibrillation and death.

CONCLUSIONS

In anaesthetised Yorkshire swine, cumulative intravenous doses of cocaine caused a significant reduction in coronary blood flow resulting in myocardial ischaemia, which cannot be attributed to epicardial vasoconstriction alone. This suggest that cocaine-induced coronary ischaemia may result from microvascular constriction, which is only partially prevented by alpha 1 blockade. In addition, direct toxic effects of cocaine on the myocardium may also contribute to the development of cardiogenic shock.

Cellular mechanism of the positive inotropic effect of hydralazine in mammalian myocardium

1. The purpose of this study was to elucidate the cellular mechanism of the positive inotropic effect of hydralazine, a vasodilator widely used for afterload reduction in patients with heart failure that has also been reported to have positive inotropic effects on the heart. After isolation, right ventricular papillary muscles from the ferret were maintained in bicarbonate-buffered salt solution (30 degrees C). A concentration-response relationship was obtained for hydralazine (10(-6) to 10(-3) M). In order to mimic different levels of catecholamine release found in heart failure, we utilized two methods of stimulation: (a) threshold punctate pulses and (b) suprathreshold punctate stimulation with voltage approximately 10% above threshold. 2. In a first group of muscles (n = 16), a maximally effective concentration of hydralazine (10(-3) M) increased peak isometric tension by 39 +/- 9% (P < 0.05). Doses lower than 10(-5) M had no significant effect. The bioluminescent Ca2+ indicator, aequorin, was loaded into a subset of these muscles (n = 7). A significant increase in peak light (i.e., intracellular Ca2+) developed, concurrently with an increase in peak tension (38 +/- 5% to 66 +/- 8%). This inotropic response was associated with a decrease in time to peak tension (ms), 221 +/- 7 to 186 +/- 5 (P < 0.05), and time to peak light, 65 +/- 4 to 52 +/- 2 (P < 0.05). These effects were markedly attenuated by pretreatment with autonomic blocking agents. 3. In a second group of muscles (n = 12), histamine was used to stimulate cyclic AMP production in the presence of propranolol. Hydralazine (3 x 10-4 M) led to a shift in the pD2 (i.e. the negative log of the concentration of histamine producing 50% of the maximal response) from 6.1 +/- 0.1 to 5.9 +/- 0.1(P <0.05), thus increasing the sensitivity of the muscles to histamine. Hydralazine also increased maximum tension from 160 +/- 77% to 195 +/- 57% (P <0.05) above baseline. Thus, hydralazine altered the potency and efficacy of histamine despite the presence of beta-adrenoceptor blockade.4. A third group of muscles were chemically skinned to examine the effects of hydralazine on myofilament Ca2+ responsiveness. Pretreatment of ferret papillary muscles with hydralazine (10-3 M)before skinning did not shift the force-pCa curve after skinning (n = 16). However, hydralazine added to previously skinned fibres desensitized the myofilaments, as indicated by a rightward shift of the force-pCa curve (n = 12). Maximum tension development was not changed.5. The pharmacological effects of hydralazine are characteristic of inotropic drugs that act mainly via cyclic AMP; however, the increase in peak tension demonstrated with histamine in the presence of hydralazine also suggests an effect on cyclic AMP-independent second messenger pathways. These data are consistent with reports that large doses of hydralazine may increase cellular levels of cyclic AMP, as well as other second messengers, by direct cardiac and indirect neuronal mechanisms.

[Effect of different preparation crafts on the content of baicalin in shuanghuanglian (SHL) injection]

The content of baicalin is stable when baicalin is added quantitatively in preparation. The time of extraction of the effective components of SHL with alcohol and the concentration of alcohol have little effect on the content of baicalin. The components can be extracted once, and the content of alcohol is preferably 85%. The pH level has greater influence on the content of baicalin, and should be controlled between 7.0 to 8.0. 0.2% activated carbon is suitable in preparation.

Randomized clinical trial of perioperative cefoxitin in preventing maternal infection after primary cesarean section

To determine the efficacy of perioperative cefoxitin in preventing infections after primary cesarean section, a randomized placebo-controlled, double-blind clinical trial was performed. Among 266 participants, those who received three perioperative 2 gm doses of cefoxitin (138) had significantly fewer serious infections (19.5% vs. 4.3%), fewer urinary tract infections (10.7% vs. 4.4%), less standard febrile morbidity (9.4% vs. 3.6%), and fewer courses of antibiotics postoperatively (23.4% vs. 11.6%). There was no reduction in the length of hospitalization. Use of perioperative cefoxitin umbilical cord is clamped are safe and efficacious in preventing infection after primary cesarean section.

Bacteriuria and subsequent mortality in women

The relation of bacteriuria to subsequent mortality was investigated in population-based cohort data from women living in Jamaica and Wales. Three surveys were done in each location over a 13-year period. Women with 10(5) or more gram-negative bacilli per millilitre of urine in three consecutive cultures over a 3-week span were considered bacteriuric for that survey. Mortality was determined at the second and third surveys. Bacteriuria was associated with increased mortality both in the crude data and in life-table analyses adjusted for the confounding effects of age and weight. The adjusted risk ratio for death between the first and third surveys was 1.5 for women bacteriuric at the first survey compared with non-bacteriuric women. For deaths between the second and third surveys, the adjusted risk ratio was highest (2.0) in women who were bacteriuric at both of the first two surveys. The adjusted risk ratio for death between the second and third surveys for women who were bacteriuric at one of the first two surveys but not at the other was 1.6.

Rationale and methods for a statewide, prospective surveillance system for the identification and prevention of nosocomial infections

Review of current methods of surveillance for nosocomial infection indicates that prospective surveillance of patients on a daily basis is the most accurate and valid method. In this paper, we detail such a method. Samples of hospitalized patients for surveillance are based on a fixed period of observation in each patient-care area. Data are collected on a detailed, standardized daily log that emphasize the recording of primary clinical data. Such a system is practical and is acceptable to infection control practitioners. Representative samples of patients are obtained. The utility of such a system for identifying preventable risk factors for the development and evaluation of programs of prevention is being tested in 12 acute-care hospitals in Rhode Island.

Bacteriuria in a population-based cohort of women

A survey for bacteriuria was conducted in a community-wide, unselected population of women 16--69 years old. The overall prevalence of bacteriuria was 3.5%. The prevalence of bacteriuria increased with age with a linear trend, but with a significant nonlinear component as well. Bacteriuria was associated with parity after correction for the effects of age. Current symptoms of dysuria and a history of previous urinary tract infection were slightly but significantly more common in women with bacteriuria. The population described should serve as an adequate base for continuing studies of the possible consequences of bacteriuria.