Mechanism of preservation of myocardial calcium channel function by pyruvate cardioplegic solution

We evaluated the effects of adding pyruvate to a cardioplegic solution on the preservation of the dihydropyridine-sensitive calcium (Ca2+) current responses to beta-adrenergic stimulation in rabbit cardiac myocytes by measurement of single-channel open probability. Single ventricular myocytes were isolated and stored in St. Thomas' solution with or without pyruvate at 4 degrees C for 2, 6, 12, or 24 hours, and cell-attached single Ca2+ channel currents recordings were made at 20 degrees to 22 degrees C after each storage period. When 0.1 micromol/L isoproterenol (ISO) was applied to the cells, the percent mean open probability of the Ca2+ channels tested in freshly isolated cells was 181% +/- 27% (n = 12) of control values. These responses decreased with an increasing duration of the hypothermic storage and were only 112% +/- 22% (n = 5) of control values after 24 hours of storage in the absence of pyruvate. Conversely, the responses were significantly preserved, to as much as 143% +/- 17% (n = 7), in the presence of 10 mmol/L pyruvate in the storage solution. The application of forskolin to stimulate adenylate cyclase or a membrane-permeable cyclic adenosine monophosphate mimicked the effects of ISO when the myocytes were stored with pyruvate. Pyruvate did not alter the open-channel kinetics or single-channel conductance and lacked any apparent direct effect on the Ca2+ channel activity. We suggest that pyruvate added to the hypothermic storage solution preserves the high-energy phosphates in myocytes that are responsible for Ca2+ channel phosphorylation via beta-adrenergic stimulation. (J Lab

Growth hormone (GH) replacement reduces total body fat and normalizes insulin sensitivity in GH-deficient adults: a report of one-year clinical experience

The effects of GH replacement on body fat composition and insulin sensitivity were assessed in GH-deficient adults. The patients were randomized into a double-blind, placebo-controlled study of human recombinant GH replacement therapy for 6 months (period 1), followed by an open phase of GH for another 6 months (period 2). Anthropometric variables, body fat composition (fat %), and biochemical parameters were measured during the trial. Measurements of in vivo insulin sensitivity were carried out at the commencement of the study and on completion of the trial by modified insulin suppression test. The modified insulin suppression test was performed both in the morning (AM) and in the afternoon (PM) to further evaluate the PM-AM steady-state plasma glucose (SSPG) pattern. We found that the GH-deficient adults had more body fat and were insulin resistant. Significant reduction in fat % and total body fat mass was found in the active arm of period 1 without alteration of body weight. Besides, we demonstrated, for the first time, the GH replacement for 6 months did not alter the insulin sensitivity, but replacement for a longer period (12 months) normalized not only the AM SSPG level but also the PM-AM SSPG pattern. We also found a positive correlation between SSPG (regardless of AM vs. PM) and fat % and total body fat mass. In conclusion, normalization of insulin sensitivity in GH-deficient adults after replacement of GH may be related to the reduction of total body fat.

Altered antigenicity of 'a' determinant variants of hepatitis B virus

The 'a' determinant of hepatitis B virus (HBV) surface antigen (HBsAg) is the most important target for diagnosis and immunoprophylaxis. Several HBV variants with point mutations within the 'a' determinant have been identified among fully vaccinated children in Taiwan. We investigated the effect of each of these mutations on the antigenic nature of the S protein by cloning and expression of the mutant S antigens in Pichia pastoris. Four variants, Ser-126, His-129, Arg-129 and Arg-145, all exhibited various degrees of altered binding of HBsAg to several monoclonal antibodies. Arg-145, a well-characterized immune escape mutant, and Arg-129 had the lowest binding capacities to all monoclonal antibodies as compared with other variants. Similar to Arg-145, the Arg-129 variant could be isolated from both vaccinated children and unvaccinated adults, thus representing a naturally occurring mutant with an altered 'a' determinant. Whether these 'a' determinant variants with altered antigenicity might gradually become major circulating strains, as a consequence of the immune pressure against the wild-type HBV created by vaccination, remains to be monitored.

Peritoneal inclusion cysts and their relationship to the ovaries: evaluation with sonography

PURPOSE

To evaluate with sonography the relationship of the ovary to the peritoneal inclusion cyst.

MATERIALS AND METHODS

The medical records, sonograms, and sonographic reports of 15 premenopausal women with surgically proved peritoneal inclusion cysts were examined. Twelve of these cases were examined prospectively. In another prospectively evaluated case, the sonogram was interpreted as revealing a peritoneal inclusion cyst; however, hydrosalpinx was confirmed with surgery. Thirteen women with peritoneal inclusion cysts had undergone pelvic surgery before sonography. Additional examination with computed tomography was performed in three women and with magnetic resonance imaging in another.

RESULTS

The ovary was detected on sonograms in 12 of 15 women with peritoneal inclusion cysts. In nine of the 12 women, the ovary was demonstrated to be inside the cyst. Ten of 12 ovaries appeared normal. Cyst diameter ranged from 7.5 to 17.4 cm (mean, 11.6 cm). Sonograms of two cysts demonstrated internal echoes. Septa were seen in 11 of the 15 cysts. Cysts were ovoid in six women and irregular in nine; they were defined by adjacent pelvic structures.

CONCLUSION

In premenopausal women with a history of pelvic surgery, the appearance on sonograms of the ovary inside a large, ovoid or irregular, anechoic cyst is characteristic of a peritoneal inclusion cyst.

Functional assessment for shoulder impingement syndrome after anterior acromioplasty

BACKGROUND

Impingement syndrome is a common cause of shoulder pain. Conservative treatment should always be initially considered. But for those patients with persistent symptoms, open acromioplasty is a reliable method to relieve pain and improve function.

METHODS

From May 1989 to September 1994, a series of 36 anterior acromioplasties for impingement syndrome of the shoulder in 34 patients was retrospectively analyzed. Among them, rotator cuff tear was found in 25, and concomitant cuff repair was performed in 20. Five shoulders were not repaired because of a massive tear with marked cuff retraction. Neer's functional criteria and Constant's functional score were used to evaluate the results of anterior acromioplasty. The postoperative evaluation included patient satisfaction, relief of pain, range of motion and full use of the shoulder.

RESULTS

Thirty-four patients with an average follow-up of 34 months were available for assessment. The average Constant's functional score was 94.7 points in the excellent group (55.5%), 77.2 points in the good group (30.5%) and 58.6 points in the poor group (13.9%).

CONCLUSIONS

Overall there was an 86% satisfactory rate by Neer's criteria. Anterior acromioplasty appears to be an effective procedure for shoulder impingement syndrome.

Experimental investigation of pulsatile flows in tubes

Based on cam-piston-valve arrangement, a mechanical pulsatile flow generator is designed to investigate sinusoidal flow and other types of pulsatile flow in straight rigid tube. Measurement reveals the relation between pressure gradient and flow rate. Numerical simulation using the k-epsilon turbulence model are carried out to compare the pulsatile flow produced by the generator with a sinusoidal flow and a physiological flow in a rigid tube. The results show that the pulsatile flow generated has similar dynamic properties to the physiological flow. Hence, the present setup can be used for in-vitro investigation of biofluid phenomena.

Observations of metabolite formation and variable yield in thiodiglycol biodegradation process : impact on reactor design

The complete microbial degradation of thiodiglycol (TDG), the primary hydrolysis product of sulfur mustard, by Alcaligenes xylosoxydans ssp. xylosoxydans (SH91) was accomplished in laboratory-scale stirredtank reactors. An Andrews substrate inhibition model was used to describe the cell growth. The yield factor was not constant, but a relationship with initial substrate concentration has been developed. Using a substrate-inhibition and variable-yield kinetic model, we can describe the cell growth and substrate consumption in batch and repeated batch fermentations. Several reactor-operating modes successfully degrade TDG concentration to below 0.5 g/L. According to the experimental results, the two-stage repeated batch operation has the best degradation efficiency, and it also can degrade 500 mM TDG (= 60 g/L) to 5 mM (= 0.7 g/L) in <5 d. A hypothesis for explaining variable-yield and byproduct formation based on the capacity and utilization of metabolic loads is presented.

Misdiagnoses in a Chinese narcoleptic patient with delayed onset of cataplexy

Narcolepsy is a chronic condition that usually afflicts the patient for decades. It is more common than is generally appreciated. However, it is likely to be misdiagnosed because doctors are unfamiliar with some of the symptoms. Its significant socioeconomic impact on the patient's quality of life warrants prompt medical attention.

Clinical implication of transient hyperglycemia in childhood

The incidence of insulin-dependent diabetes (IDDM) in Chinese is much lower than for Western persons. The study was designed to determine whether Chinese children with transient hyperglycemia would develop diabetes as frequently as Western children. Ten children presenting with transient hyperglycemia were investigated using glucagon stimulation test, oral glucose tolerance test (OGTT) and i.v. glucose tolerance test (IVGTT) to estimate pancreatic insulin secretory function. They were followed up for one to three years. Islet cell antibodies and insulin autoantibodies were also measured. During the follow-up period, 2 of the 10 children developed diabetes at 1 month and 1 year, respectively, after the occurrence of transient hyperglycemia. Both of them had lower C-peptide peak level to glucagon stimulation, decreased first phase insulin release to IVGTT and a diabetic sibling. Islet cell antibodies and insulin autoantibodies were all negative except in one of the two children who later developed diabetes. Although it is still premature owing to the small sample size to conclude that Chinese children with transient hyperglycemia are less likely to develop diabetes than Western children, it is advisable to closely follow up those with a family history of IDDM who seem to be at the greatest risk.

Active transposition in zebrafish

We have identified a new family of Tc1-like transposons in the zebrafish, Danio rerio. The sequence of a candidate active transposon, deduced from sample Tzf elements, shows limited resemblance to the previously described Tdr1 elements of zebrafish. Both the Tzf and the Tdr elements are extremely abundant in zebrafish. We describe here a general strategy for detecting transposition events in a complex genome and demonstrate its utility by selectively monitoring hundreds of potentially active Tzf copies in the zebrafish genome against a background of other related elements. We have followed members of a zebrafish pedigree, using this two-dimensional transposon display strategy, to identify the first examples of active transposition of such elements in vertebrates.

Expression pattern of nuclear p53 is unique in COS-1 cells

As p53 is transcriptionally inactive in COS-1 cells, we felt it would be interesting to study the relative time course of expression of nuclear p53 and the onset of S phase. Our results indicated that the expression of nuclear p53 lagged behind the onset of S phase in COS-1 cells. In addition, rapid nuclear expression of p53, probably resulting from nuclear translocation, occurred immediately after the addition of serum into COS1 cells. No such phenomena were found in B104-1 and BHK cells.

Prevalence estimate of elevated pediatric blood leads: two Air Force bases

After the occurrence of several cases of lead poisoning at Offutt and Randolph Air Force Bases, a cross-sectional study on all children of age 12 or younger was initiated to identify those children with possibly undue lead exposure. A total of 1102 and 784 children at these two bases, respectively, were tested for blood lead values. The aim of this study was to estimate the prevalence of elevated blood lead levels of young children living in on- or off-base housing at the two air force bases. To account for analytical errors and the within-person variability in blood lead measurements, a bivariate lognormal model was employed to estimate the true blood lead values of those children whose initial measurements were 10 micrograms/dL or greater. As a result of accounting for the analytical errors and within-person variance in blood lead measurements, many cases of elevated blood lead levels turned out to be false positives. It was also shown that the relative risk for young children at the two bases having elevated blood leads was the same regardless of where they lived and how old they were. By pooling together the cases, a point estimate for the prevalence of elevated blood leads among young children was 4.2 per 1000 children, with a 95% confidence interval of 1.8 to 8.4 children per 1000 children.

Genetic susceptibility to Marek's disease virus of local chickens in Taiwan

Marek's disease is a contagious disease in chickens caused by Marek's disease virus (MDV) infection. Invasion of very virulent MDV (vvMDV) was considered to be a major cause of vaccine break, resulting in a large economic loss in the poultry industry. Two strains of the vvMDV (strains LTB-1 and LTS-1) have been reported in Taiwan, causing early mortality and formation of lymphoid tumors in broilers and layers. In this study, we report the susceptibility of local chickens in Taiwan to inoculation with strains LTB-1 and LTS-1 at 1 day of age. Five lines of Taiwanese local chickens (lines B, D, L2, KM, and BG) were used to compare the susceptibility to vvMDV. The chicks were inoculated via intraperitoneal route at 1 day of age. All MDV-inoculated chickens showed atrophy of various lymphoid organs. Protection tests were also conducted in local chickens, using vaccine of herpesvirus of turkey (HVT) at 1 day of age followed by vvMDV challenge at 10 days of age. Among the vaccinated chickens, 0-20.0% showed early mortality, and tumor occurrences in visceral organs and in peripheral nerves were 66.7%-100% and 0-27.2%, respectively. From these results, it could be concluded that local chickens in Taiwan have different susceptibilities to vvMDVs. Furthermore, vaccination with HVT showed no protective effect against Taiwanese vvMDV isolate challenge in this experiment.

Exogenous pulmonary surfactant replacement therapy in a neonate with pulmonary hypoplasia accompanying congenital diaphragmatic hernia--a case report

Pulmonary hypoplasia(PH) commonly occurs in association with oligohydramnios and other congenital anomalies, especially congenital diaphragmatic hernia (CDH). Pulmonary hypoplasia is an important factor, as persistent pulmonary hypertension, in the prognosis of CDH. In some reports, there is a decrement of pulmonary surfactant in PH accompanying CDH. Recently, there are some reports that exogenous pulmonary surfactant therapy is effective in experimental animal model and neonatal respiratory distress with PH. We report a case of a 5 day-old male neonate, who had shown dyspnea and diagnosed as left pulmonary hypoplasia accompanying CDH. The CDH was surgically treated and the ipsilateral PH, with intratracheal administration of exogenous pulmonary surfactant postoperatively. After exogenous pulmonary surfactant application, the left lung volume was increased on chest roentgenogram and lung perfusion scan findings, and there was an improvement in oxygenation and clinical manifestations. We suggest that postoperative exogenous pulmonary surfactant replacement therapy is effective in the case of PH and further trials are needed to clarify the optimal dose and timing of supplementation of surfactant for treatment of infants with PH accompanying CDH.

Dual vasoactive effects of tolazoline on rabbit pulmonary arteries

OBJECTIVES

To determine the vasoactive effects of tolazoline on isolated rabbit pulmonary arteries.

DESIGN

Prospective, in vitro, randomized, controlled trial.

SETTING

Experimental laboratory in a university-affiliated hospital.

PARTICIPANTS

New Zealand White Rabbits.

INTERVENTIONS

The pulmonary artery rings were obtained via thoracotomy. Their vasoactive responses were assessed in the presence and absence of intact endothelium and with or without precontraction by norepinephrine (NE, 3 x 10(-6) M) or potassium chloride (KCl, 3 x 10(-2) M). Using a tissue bath preparation, cumulative concentration response curves of tolazoline were obtained at different concentrations (10(-9) to 10(-4) M) after a period of stabilization.

MEASUREMENTS AND MAIN RESULTS

Tolazoline caused vasoconstriction of isolated pulmonary arteries without any pretreatment. The magnitude of the constriction was dose related and reached 300 g/g wet tissue at a concentration of 10(-4) M. On KCl-precontracted pulmonary arteries, tolazoline caused significant dose-related vasoconstriction. On the NE-precontracted vessel rings, it elicited significant dose-dependent vasodilation up to 60% relaxation at 10(-5) M. All the above effects were endothelium independent.

CONCLUSIONS

Tolazoline has dual endothelium-independent vasoactive effects, causing vasoconstriction on isolated rabbit pulmonary arteries, either untreated or precontracted with KCl, and vasodilation on those precontracted with NE. Tolazoline may act as a competitive alpha-adrenoceptor blocking agent.

A case of unrelenting pursuit of castration

OBJECTIVE

Explore the limitations of the classification of body dysmorphic disorder.

CLINICAL PICTURE

A chinese male relentlessly pursued castration to relieve painful erections which were never substantiated. The testes and corporaspongiosum had been removed. No psychotic symptom was prominent.

TREATMENT

Cognitive therapy and psychotropics were tried.

OUTCOME

The remaining corpora cavernosa was removed subsequently.

CONCLUSION

The distorted somatic perception and secondary cognitive amplification (painful erections) could represent a variant of body dysmorphic disorder involving internal body image; diagnostic classifications should accommodate such a category.

Comparison of antihypertensive effects of nicardipine with nitroglycerin for perioperative hypertension

BACKGROUND

To compare the efficacy of intravenous (iv) nicardipine with nitroglycerin for the treatment for patients with perioperative hypertension.

METHODS

Forty patients with perioperative hypertension randomly divided into two groups were treated with intravenous calcium entry blocker, nicardipine, or vasodilator, nitroglycerin. Haemodynamic measurements including mean arterial and pulmonary arterial pressure, central venous and pulmonary capillary wedge pressure, and cardiac output were recorded; peripheral and pulmonary vascular resistance were calculated.

RESULTS

Both medications were effective in reducing blood pressure and controlling haemodynamics. During the maintenance by continuous iv infusion, nicardipine controlled hypertension more rapidly than nitroglycerin (nicardipine 10.5 +/- 2.5 min and nitroglycerin 18.7 +/- 2.8 min, p < 0.05) without significant alteration in heart rate. The total frequency of dose adjustments required to achieve therapeutic response was significantly less in the nicardipine-treated group (2.5 +/- 0.3 for nicardipine and 6.2 +/- 1.4 for nitroglycerin, p < 0.05). Incidence of hypotensive episodes during the infusion were observed in both groups [nicardipine 5% (1/20) and nitroglycerin 30% (6/20), p < 0.05].

CONCLUSIONS

Intravenous nicardipine is as effective as nitroglycerin in the treatment of perioperative hypertension. Specific advantages have been identified such as stable dose-response effect, less hypotensive and tachycardial effects during the use of iv nicardipine in treatment of hypertensive patients.

Long-term propofol infusion and airway management in a patient with Goldenhar's syndrome

A 2-year-old patient of Goldenhar's syndrome received an operation for corneal transplantation. Difficult endotracheal intubation from the congenital anomaly was treated with laryngeal mask airway and pediatric fiberoptic laryngoscope. Long-term propofol infusion (> 10 h) for anaesthetic maintenance in this small child was used with rapid and smooth recovery.

Comparative vasoactive effects of amrinone on systemic and pulmonary arteries in rabbits

Amrinone has been increasingly used in management of low cardiac output syndrome during anesthesia, particularly when associated with right heart failure and pulmonary hypertension. This in vitro study was performed to determine and compare the direct vasoactive effects of amrinone on isolated rabbit systemic and pulmonary arteries. Responses of aortic and pulmonary artery rings from New Zealand white rabbits were assessed in the presence and absence of intact endothelium and with or without precontraction by norepinephrine (NE, 3 x 10(-6)M) or potassium chloride (KCl, 3 x 10(-2)M). Using a tissue bath preparation, cumulative concentration response curves of amrinone were obtained at different concentrations after a period of stabilization. Amrinone caused a dose-related vasodilation of NE-precontracted aortic and pulmonary arteries. It elicited about 65% and 90% relaxation, respectively, at a concentration of 300 mumol/L. Amrinone also induced a dose-related vasodilation of KCl-precontracted aortic and pulmonary arteries but to a lesser degree. All these effects were endothelium independent. By comparison, amrinone caused more relaxation in both NE- and KCl-precontracted pulmonary artery than aortic rings. In conclusion, amrinone has significant endothelium-independent, direct vasodilatory effects on isolated rabbit systemic and pulmonary arteries, more pronounced in the latter, particularly NE-precontracted vessels. Amrinone may have some calcium channel-blocking effect.

A Bayesian framework for understanding texture segmentation in the primary visual cortex

This paper presents a mathematical theory for understanding the computations involved in texture segmentation in the primary visual cortex. We propose that texture segmentation is a part of the early visual system's overall strategy to infer surfaces of objects in a visual scene. Based on this insight, we use the Bayesian inference paradigm to formulate the texture segmentation problem into a maximum a posteriori surface inference problem. The dynamical system for finding the optimal solution of this problem can be characterized by two concurrent and interactive processes: a gradual sharpening of the boundary signals and a simultaneous smoothing of the surface signals. The behavior of these dynamical processes was studied using both analytical and computational methods. We present some computational results and mathematical predictions. This theory suggests a novel framework for understanding the functional roles of the complex cells in the primary visual cortex.

Simultaneous in vivo comparison of two-versus three-wavelength mixed venous (Svo2) oximetry catheters

OBJECTIVE

Venous oximetry catheters provide useful realtime information about mixed venous hemoglobin saturation (Svo2). Currently available systems utilize either two or three wavelengths of light to obtain these measurements. Previous animal and clinical studies have attempted to compare the accuracy of these two devices under similar circumstances. However, the relative accuracy of the two-wavelength versus three-wavelength systems has never been assessed under identical conditions. For this purpose, we designed an animal model for simultaneous measurement of Svo2, over a wide range of physiologic and pathologic states.

METHODS

Seven anesthetized swine underwent simultaneous placement of two- and three-wavelength catheters. Paired data points consisted of values obtained from a reference oximeter and from each of the catheters. Observations were obtained every 15 min during the following manipulations: (1) eucarbic hypoxia induced by reducing FiO2 to 0.18, 0.15, and 0.12 for 15 min each; (2) stimulated surgical manipulation; and (3) hypovolemic shock produced by hemorrhage to a mean arterial pressure of 50 torr for 1 hr. Data were analyzed by calculation of mean error (bias) and precision for each system in comparison with the oximeter.

RESULTS

The overall error of the two-wavelength system was +0.15%, with a precision of +/- 2.52%. The three-wavelength system had an overall error of +3.71%, with a precision of +/- 2.30%. Overall correlation between catheter Svo2 and oximeter values was the same for both devices (r = 0.99).

CONCLUSIONS

Both currently available in vivo spectrophotometric systems are capable of producing satisfactory results over wide ranges of Svo2. In contradistinction to older reports, we found that the two-wavelength Svo2 system produced results equivalent to those obtained from the three-wavelength device. In this regard, there is no detectable advantage in accuracy to measuring in vivo Svo2 with three rather than with two wavelengths.