DDT Polymorphism and the Lethality of Crystal Forms.

DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane), a contact insecticide with a rich and controversial history since its activity was discovered in 1939, has long been thought to be monomorphic. Herein we report the discovery and characterization of a second polymorph, designated Form II, which can be isolated as single crystals, but converts very slowly at room temperature to the form reported previously, now designated as Form I. Computations based on an evolutionary algorithm for crystal structure prediction revealed that Forms I and II are among the four lowest energy crystal structures of fifty calculated. A preliminary study of the contact insecticidal activity toward fruit flies (Drosophila melanogaster) indicates that Form II is more active, suggesting opportunities for more effective solid-state formulations that would allow reduced amounts of DDT, thereby minimizing environmental impact.

Glycerol-enhanced mini-polyacrylamide gel electrophoresis for the separation of differentially expressed DNA fragments in cDNA representational difference analysis.

Representational difference analysis (RDA) is a widely used technique in molecular biology. However, in practice, its efficiency depends on a rapid and reliable separation of the RDA fragments prior to cloning. To achieve this, we have compared and combined the separation efficiencies of conventional and MetaPhor agarose gel electrophoresis (MAGE) with a glycerol-enhanced mini-polyacrylamide gel electrophoresis (PAGE) system (Gem-PAGE). As anticipated, MetaPhor agarose provided significantly improved resolution over conventional agarose electrophoresis, but the latter remains useful to rapidly confirm the presence of RDA-enriched difference products and direct the concentration of MetaPhor agarose subsequently used for further fragment separation. Additional improvements in resolution were possible by using the Gem-PAGE system. The effect of glycerol on band definition of PAGE was most noticeable as the acrylamide to glycerol ratio (A:G) approached 1:2. Gels in which the A:G ratio was significantly above or below this resulted in both poor morphology and impaired resolution of the bands. By exploiting sequentially agarose-based and Gem-PAGE electrophoresis, the goal in RDA of "one band one product" is now realizable.

A novel speech controller for radio amateurs with a vision impairment.

This paper describes a portable speech controller system for persons with a vision impairment to adjust the channel frequency of a radio set via speech commands. The speech commands are recognized on a general-purpose digital signal processor using a hidden Markov model (HMM), and are used to remotely control radio channel changes.

Effects of intracranial hypertension on steady and pulsatile haemodynamics in dogs.

1. Intracranial hypertension (ICH) tends to elicit various cardiovascular changes. Previous studies on the haemodynamic responses to ICH have been confined mainly to measurements of arterial pressure (AP), cardiac output (CO) and total peripheral resistance (TPR). In the present study, we used the technique of arterial impedance analysis for a complete assessment of steady and pulsatile haemodynamics in ICH. 2. In anaesthetized dogs, aortic pressure and flow waves were obtained with high-fidelity Millar sensors. The pressure and flow waves were subjected to Fourier transformation (frequency analysis) for an analysis of impedance spectra. Intracranial pressure (ICP) was elevated by inflation of an epidural balloon. At an ICP of 50 mmHg, the changes in steady and pulsatile haemodynamics were slight. 3. Haemodynamic changes became evident at an ICP of 100 mmHg. The mean AP was elevated by 31 mmHg (+32%) and heart rate (HR) was reduced by 25 b.p.m. (-18%). There was also a significant decrease in CO by 27% and large increase in TPR by 82%. With respect to pulsatile haemodynamics, an elevation of ICP to 100 mmHg caused significant increases in characteristic impedance by 45% and wave reflection by 53%. Arterial compliance was reduced by 50%. The ventricular oscillatory work was increased without a significant change in steady work. 4. The results indicate that ICH causes constriction of resistance vessels to affect AP and TPR. Because the pulsatile haemodynamics reflect mainly the Windkessel functions, ICH also induces stiffness of the large vessels to affect arterial impedance, pulse wave reflection and ventricular oscillatory work.

Hemodynamic and neurohumoral changes after abdominal aortic constriction in rats.

Cardiac after-load, neurohumoral reaction and the secondary cardiac hypertrophy were studied in six groups of Sprague-Dawley (SD) rats with abdominal aortic constriction. We found that abdominal aortic constriction above the renal arteries decreased the heart rate and cardiac output, and increased the pulse pressure. These abnormalities would return to normal after constriction ended. Captopril, propranolol and prazosin could reduce the increase of pulse pressure but still had decreased in cardiac output of rats with abdominal constriction. Aortic constriction also increased the aortic impedance and cardiac load but decreased aortic compliance. These changes could also be lessened by captopril, propranolol and prazosin. We have confirmed that aortic constriction can induce secondary cardiac hypertrophy, but the pathogenesis might be due to multiple factors.

ATP-sensitive potassium-channel-opening activity of CL-065, a 3-[(substituted-carbonyl)amino]-2H-1-benzopyran, in the rat.

The pharmacological activity of CL-065 (trans-3-acetamido-2,2-dimethyl-4-hydroxy-3,4-dihydro-2H-1-benzopyran-6- carbonitrite) was investigated in anaesthetized spontaneously hypertensive rats (SHR) and isolated thoracic aorta of Sprague-Dawley rats. The intravenous administration of CL-065 [0.1-2.0 mg kg(-1)] to anaesthetized SHR induced a dose-dependent reduction of mean arterial pressure (MAP) with maximum effect approximately 5 min after injection and which persisted for over 3 h. CL-065 also induced a reflex tachycardia which seemed to parallel the time course of the hypotensive effect. The hypotensive effect of CL-065 was blocked by pretreatment with glibenclamide [5 mg kg(-1), i.v.], a specific ATP-sensitive potassium (KATP) channel blocker. Moreover, CL-065 (0.01-10 microM) resulted in dose-dependent vasodilatory effects on phenylephrine (0.3 microM)-induced vasoconstriction in isolated thoracic aorta. The vasorelaxation elicited by CL-065 was antagonized competitively by pretreatment with glibenclamide (0.1-1.0 microM; pA2 = 6.90+/-0.09; slope = 1.03+/-0.18). Similarly, the other two KATP-channel openers cromakalim (1.0 nM-1.0 microM) and nicorandil (0.1-30 microM) also induced vasorelaxation in thoracic aorta. The EC50 of cromakalim, CL-065 and nicorandil (i.e. the doses having half the maximum effect) were approximately 0.083, 0.17, and 4.5 microM, respectively, for phenylephrine (0.3 microM)-induced vasoconstriction in isolated thoracic aorta. Moreover, increased extracellular potassium levels (20-60 mM) resulted in concentration-dependent attenuation of the vasodilator effect of CL-065. In conclusion, CL-065 induces a depressor effect via activation of KATP channels.

Acute effects of nitric oxide blockade with L-NAME on arterial haemodynamics in the rat.

1. We employed the technique of impedance spectral analysis to investigate the role of endogenous nitric oxide (NO) in the regulation of steady and pulsatile haemodynamics in Wistar Kyoto rat (WKY). 2. A total of 12 WKYs was anaesthetized with pentobarbitol sodium (40 mg kg-1, i.p.) and artificially ventilated with an animal respirator. The aortic pressure wave was monitored with a high fidelity Millar sensor, and aortic flow wave with an electromagnetic flow probe. The pressure and flow waves were subjected to Fourier transform for the analysis of impedance spectra. 3. The baseline cardiovascular parameters were mean arterial pressure (APm) 95 +/- 9 mmHg, heart rate (HR) 338 +/- 9 b.p.m., stroke volume (SV) 0.23 +/- 0.01 ml, cardiac output (CO) 77.8 +/- 1.6 ml min-1, total peripheral resistance (TPR) 98 +/- 11 (x10(3)) dyne s cm-5, characteristic impedance (Zc) 2046 +/- 141 dyne s cm-5, arterial compliance at mean AP (Cm) 3.78 +/- 0.22 microliters mmHg-1 and backward pulse wave (Pb) 12.9 +/- 0.6 mmHg. 4. An NO synthase inhibitor, NG-nitro-L-arginine monomethyl ester (L-NAME) was administered at graded intravenous doses. This agent caused dose-dependent increases in AP and TPR with decreases in HR. At an accumulative dose of 10 mg kg-1, APm was increased by 29 +/- 3 mmHg (+31%) and TPR by 49 +/- 6 (x10(3)) dyne s cm-5 (+50%), while HR was reduced by 37 +/- 5 b.p.m. (-11%) and CO by 10.4 +/- 0.8 ml min-1 (-14%). The pulsatile haemodynamics including Zc and Pb were slightly increased by 14-15%. Cm was decreased by 1.09 microliters mmHg-1 (-29%). L-NAME also did not significantly affect the ventricular work including the steady, oscillatory and total work. 5. Aminoguanidine, a specific inhibitor for inducible NO synthase (iNOS), in dose 10-60 mg kg-1 i.v. did not alter the AP, HR and other parameters. The result indicated that blockade of constitutive NOS, but not iNOS is involved in these changes. 6. Angiotensin II (Ang) in various infusion doses was used to produce a profile of AP increase similar to that caused by L-NAME. Ang remarkably increased Zc, while TPR was moderately elevated. The pattern of haemodynamic changes was different from that following L-NAME. 7. The results suggest that blockade of the endogenous NO affects predominantly the arterial pressure and peripheral resistance. The Windkessel functions such as arterial impedance and pulse wave reflection are slightly increased. Ventricular works are not significantly altered.

Endogenous nitric oxide on arterial hemodynamics: a comparison between normotensive and hypertensive rats.

Endogenous nitric oxide (NO) plays an important role in maintaining a vasodilator tone. In the present study, we compared the effects of NO blockade on the steady and pulsatile components of arterial hemodynamics between spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto strain (WKY), 22-26 wk of age. In the first series of experiments, various doses (1-30 mg/kg i.v.) of N(G)-nitro-L-arginine methyl ester (L-NAME) were administered to block the NO release in anesthetized WKY and SHR. In both WKY and SHR, L-NAME caused a dose-dependent increase in arterial pressure (AP) with a decrease in heart rate (HR). The maximal effects of L-NAME on AP and HR occurred at a dose of 10 mg/kg. Both the AP increase and HR decrease were higher in SHR (AP, +38 +/- 4 mmHg; HR, -49 +/- 5 beats/min) than WKY (AP, +22 +/- 3 mmHg; HR, -33 +/- 5 beat/min). In other series, the technique of impedance spectral analysis was employed to investigate the effects of L-NAME (10 mg/kg i.v.) on the arterial hemodynamics. The aortic pressure and flow waves were recorded and subjected to Fourier transform for the analysis of impedance spectra. Both in WKY (n = 12) and in SHR (n = 12), L-NAME significantly increased AP and total peripheral resistance (TPR). The pulsatile and frequency-dependent hemodynamics including characteristic impedance, wave reflection, and ventricular work were only slightly altered. Despite higher resting values of AP and TPR in SHR (mean AP, 154 +/- 7 mmHg; mean TPR, 204 +/- 17 x 10(3) dyn x s x cm(-5)) than WKY (mean AP, 94 +/- 6 mmHg; mean TPR, 98 +/- 12 x 10(3) dyn x s x cm(-5)), the magnitudes of AP and TPR increments after NO blockade were significantly higher in SHR (AP, +37 +/- 3 mmHg; TPR, +124 +/- 16 x 10(3) dyn x s x cm(-5)) than in WKY (AP, +24 +/- 3 mmHg; TPR, +45 +/- 7 x 10(3) dyn x s x cm(-5)). The continuous formation of endogenous NO affects predominantly the AP and peripheral resistance in both WKY and SHR. The windkessel functions, such as impedance spectra, pulse-wave reflection, and ventricular work, are less affected after NO blockade. In addition, the effects of NO release on the AP and TPR appear to be enhanced in rats with established hypertension.

The effect of glycolic acid on the treatment of acne in Asian skin.

BACKGROUND: Glycolic acid has become important and popular for treating acne. OBJECTIVE: To evaluate the efficacy and safety of serial glycolic acid peels with glycolic acid home care products on facial acne lesions and other associated skin problems. METHODS: We collected 40 Asian candidates with moderate to moderately severe acne. They were divided into two groups according to the degree of greasiness of their facial skin. The two groups' members were treated with four series of 35% and 50% glycolic acid peels, respectively. They also used 15% glycolic acid home care products during this study period. The improvement of acne as well as other associated problems were assessed by both the physicians and the patient themselves. RESULTS: Significant resolution of comedones, papules, and pustules was found. The skin texture of each candidate was dramatically rejuvenated. Consistent and repetitive treatment with glycolic acid was needed for the apparent improvement of acne scars and cystic lesions. The follicular pores also became comparatively smaller. Furthermore, most of the candidates had much brighter and lighter looking skin. Only small percentage of patients (5.6%) developed side effects. CONCLUSION: Glycolic acid has considerable therapeutic value for acne with minimal side effects even in Asian skin. It may be an ideal adjunctive treatment of acne.

Nitric Oxide in Systemic and Pulmonary Hypertension.

Endothelium-derived nitric oxide (NO) is an important gas molecule in the regulation of vascular tone and arterial pressure. It has been considered that endothelial dysfunction with impairment of NO production contributes to a hypertensive state. Alternatively, long-term hypertension may affect the endothelial function, depress NO production, and thereby reduce the dilator action on vasculatures. There were many studies to support that endothelium-dependent vasodilatation was impaired in animals and humans with long-term hypertension. However, results of some reports were not always consistent with this consensus. Recent experiments in our laboratory revealed that an NO synthase inhibitor, N(G)-nitro-L-arginine monomethyl ester (L-NAME) caused elevation of arterial pressure (AP) in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). The magnitude of AP increase following NO blockade with L-NAME was much higher in SHR than WKY. In other experiments with the use of arterial impedance analysis, we found that L-NAME slightly or little affected the pulsatile hemodynamics including characteristic impedance, wave reflection and ventricular work. Furthermore, these changes were not different between SHR and WKY. The increase in AP and total peripheral resistance (TPR) following NO blockade in SHR were significantly greater than those in WKY, despite higher resting values of AP and TPR in SHR. In connection with the results of other studies, we propose that heterogeneity with respect to the involvement of NO (impairment, no change or enhancement) in the development of hypertension may exist among animal species, hypertensive models and different organ vessels. Our study in SHR provide evidence to indicate that the effects of basal release of NO on the arterial pressure and peripheral resistance are not impaired, but enhanced in the hypertensive state. The increase in NO production may provide a compensatory mechanism to keep the blood pressure and peripheral resistance at lower levels. The phenomenon of enhanced NO release also occurs in certain type of pulmonary hypertension. We first hypothesized that a decrease in NO formation might be responsible for the pulmonary vasoconstriction during hypoxia. With the measurement of NO release in the pulmonary vein, we found that ventilatory hypoxia produced pulmonary hypertension accompanying an increase in NO production. Addition of NO inhibitor (L-NAME), blood or RBC into the perfusate attenuated or abolished the NO release, while potentiating pulmonary vasoconstriction. During hypoxia, the increased NO formation in the pulmonary circulation similarly exerts a compensatory mechanism to offset the degree of pulmonary vasoconstriction.

Beta-Adrenergic Mechanisms in Arterial Hemodynamics: A Comparison between Normotensive and Hypertensive Rats.

The purpose of this study was to determine whether beta-adrenergically mediated cardiovascular functions such as arterial pressure (AP), heart rate (HR), stroke volume (SV), cardiac output (CO), peripheral resistance (R(p)), arterial impedance (Z(c)), mean arterial compliance (C(m)) and pulse wave reflection (P(b)) were altered in the spontaneously hypertensive rat (SHR) compared to the normotensive Wistar Kyoto rat (WKY). In pentobarbital-anesthetized and artificially ventilated rats, the aortic pressure wave was recorded with a high-fidelity Millar sensor, and aortic flow wave with an electromagnetic flow probe. The pressure and flow waves were subjected to Fourier transform so as to analyze impedance spectra. Acute beta-adrenergic blockade was produced by an intravenous injection of propranolol (nonselective) and atenolol (selective beta(1)-blocker) at doses of 2 and 5 mg/kg, respectively. Steady-state parameters were obtained 15-20 min after intravenous administration. The SHR had higher AP, HR, R(p) and Z(c) than the WKY. SV and CO remained unaltered while C(m) was lower. In response to propranolol, the mean AP was increased by 7 mm Hg in the WKY, but did not change in the SHR. Moreover, significant decreases occurred in HR, CO and C(m) in addition to increases in R(p), Z(c) and P(b). These changes between the SHR and WKY were only slight. Atenolol caused decreases in AP, HR and CO in both SHR and WKY, but did not significantly alter the R(p), Z(c), C(m) and P(b). Again, the atenolol-induced changes in AP, HR and CO did not appear to be significantly different between SHR and WKY. The results indicate that beta-adrenergic effects on the heart, Windkessel and resistance vessels are neither greatly enhanced nor impaired during the development of hypertension. In the hypertensive state, significant beta-adrenergic mechanisms still exert tonic vasodilatory effects on the large and small arterial system. Copyright 1996 S. Karger AG, Basel

Characterization of arterial hemodynamics in rats with established hypertension.

In long-term hypertension, hemodynamic alterations are associated with functional and structural changes in the cardiovascular system. The technique of arterial impedance spectral analysis has long been used to characterize the arterial hemodynamics of steady and pulsatile components in human hypertension. Although rats with spontaneous hypertension (SHR) are the most common model for studies of primary hypertension, characterization of complete hemodynamic parameters has not been accomplished in this animal model. In the present experiment, aortic flow and pressure waves were recorded in anesthetized, open-chest and ventilated rats. Arterial impedance spectral analysis was employed to obtain steady and pulsatile hemodynamic parameters. A total of 26 SHRs (22-24 wk) and 22 age-matched normotensive WKYs was used. The purpose was to provide a comprehensive analysis of arterial hemodynamics in rats with established hypertension. The SHR had higher arterial pressure (50% increase over the control) than WKY. The total peripheral resistance was elevated by 57%. Stroke volume was decreased by 23% and heart rate increased by 18% without a significant change in cardiac output. The characteristic impedance was increased by 43%, while arterial compliance was decreased by 52%. There were also big rises in ventricular work and wave reflection. The results provide quantitative analysis of the alteration in arterial hemodynamics of steady and pulsatile components in rats with established hypertension. In long-term hypertension, the hemodynamics reflect functional abnormalities in the resistance and Windkessel vessels.

The correlation of cardiac mass with arterial haemodynamics of resistive and capacitive load in rats with normotension and established hypertension.

In hypertensive animals and humans, cardiac hypertrophy may occur as a consequence of an external load on the heart. Several studies have suggested that the non-pulsatile components of arterial haemodynamics, such as arterial pressure and vascular resistance, do not adequately represent the ventricular afterload and are not well correlated with the degree of cardiac hypertrophy (CH). The present study was undertaken to analyse the correlation between the degree of CH and various haemodynamic parameters in the spontaneously hypertensive rat (SHR) with established hypertension. A total of 36 SHRs (6-8 months) with a tail-cuff pressure above 190 mm Hg were used. Control data were obtained from 32 age-matched normotensive Wistar Kyoto rats (WKY). Animals were anaesthetized with pentobarbitone sodium (40 mg/kg i.p.) and artificially ventilated with a respirator. A Millar catheter with a high-fidelity pressure sensor was used to record the aortic pressure and an electromagnetic flow transducer to monitor the aortic flow. The pressure and flow signals were subjected to Fourier transformation for the analysis of the arterial impedance spectrum. The left ventricular weight-to-body weight ratio (LVW/BW) was taken as a measure of the degree of CH. The measured haemodynamic parameters in these anaesthetized, open-chest SHRs were systolic pressure (SP) (mean +/- SE) 172 +/- 4 mm Hg, diastolic pressure (DP), 120 +/- 3 mm Hg, pulse pressure (PP) 52 +/- 2 mm Hg, peripheral resistance (Rp) 344,032 +/- 8,012 dyne.s.cm-5, characteristic impedance (Zc) 6,442 +/- 313 dyne.s.cm-5, the impedance modulus at the first harmonic (Z1) 26,611 +/- 1,061 dyne.s.cm-5, mean arterial compliance (Cm) 0.87 +/- 0.04 microliter/mm Hg and LVW/BW 3.092 +/- 0.026 mg/g.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of left ventricular functional status using thermodynamic indices.

Conventional methods to assess cardiac contractility have been focused on the mechanical properties of the myocardium. Many of these have suffered from theoretical and practical drawbacks. In this study, we have attempted to evaluate the left ventricular contractile status using the thermodynamic principle and compared these indices with the conventional index (dP/dt). A total of 8 mongrel dogs were anesthetized and artificially ventilated. A Millar catheter with high-fidelity multiple sensors was inserted into the aorta to record the simultaneous changes in aortic flow and pressure waves. Cardiac inotropy was increased by graded doses (2-32 micrograms/kg/min) of dobutamine. Angiotensin injection (100-300 micrograms) to achieve a blood pressure elevation of 30 mmHg was employed for afterload augmentation. Preload was increased by rapid infusion of 6% dextran solution (20 ml/kg). Several thermodynamic parameters were calculated at steady state during the control period and after drug interventions. These included power-averaged rate of power density generation (ARPD), peak ejection rate of change of power (PREP), energy-averaged power density (APD) and frequency-normalized ARPD (FARPD). PREP and APD were unchanged by afterload increment while FARPD, ARPD and dP/dt decreased significantly with an increase in afterload, ARPD was highly sensitive to an increased preload (p < 0.001), and PREP was also changed significantly by an increase in preload. dP/dt was boarderlinely affected by Dextran infusion (p = 0.05), and APD was independent of preload (P > 0.05). Inotropic stimulation increased ARPD, PREP, APD, FARPD and dP/dt by 139.0 +/- 48.0%, 98.0 +/- 51.4%, 74.0 +/- 49.7%, 60.0 +/- 30.4% and 44.6 +/- 10.4%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of snake venom cardiotoxin (a membrane-disruptive polypeptide) with human erythrocytes.

The action of 7.2 microM cardiotoxin on 0.25% human erythrocytes in a plasma extender solution was studied by the interaction of toxin with intact red blood cells and subsequent hemolysis of the cells. The binding of toxin to cells was completed within 10 min, whereas the membrane rigidity was weakened in a non-lytic period for about 25 min. The toxin molecules bound almost exclusively to the membrane. The bound toxin could not be liberated with either 0.5% Triton X-100 or 0.1 N NaOH. The degree of binding was slightly reduced in the presence of 10 mM mono- and divalent inorganic salts. The action of toxin might weaken the in situ association of several proteins that are linked with band 3 protein of the membrane, thus making the cells fragile and altering the shape of the cell to a smooth sphere.

Membrane disintegration and hemolysis of human erythrocytes by snake venom cardiotoxin (a membrane-disruptive polypeptide).

The action of 7.2 microM cardiotoxin on 0.25% (v/v) human erythrocytes in plasma extender solution was studied by osmotic fragility and hemolysis. The toxin loosened the membrane rigidity without lysis for about 25 min and then the cells hemolyzed for about 6 h at 37 degrees. The membrane was not perturbed at 15 degrees. The hemolysis of cells was optimal at 37 degrees and virtually stopped below 20 degrees. Both events could be suppressed by adding inorganic salts or toxin antibody. Once the membrane was loosened, the addition of phospholipase A2 would potentiate the disintegration of erythrocytes. In contrast, hemolysis of erythrocytes by (Lys)n lacked a non-lytic period and was temperature independent and insensitive towards salts and phospholipase A2.