[The application of artificial neural network based on ambiguous function to heart sound classification]

In this study the artificial neural network was applied to heart sound classification. The network input data are ambiguous function, hence the crossterm problem of Wigner distribution is avoided. The simulation result shows that this is an effective technique. A suboptimal network model was proposed by many times of training and checking. The main factors related to network property were also discussed.

Facial and autonomic responses to biological and artificial olfactory stimuli in human neonates: re-examining early hedonic discrimination of odors

Responses of awake and asleep 3-day-old human neonates were recorded to the presentation of artificial (vanillin, butyric acid, formula milks) and biological (breast milk, amniotic fluid) odorants matched on subjective intensity and trigeminal dimensions. The responses included behavioral (facial and oral movements) and autonomic (respiration, differential skin temperature) measures. The neonates reacted with significant facial and respiratory changes to low concentrations of olfactory stimuli during the various behavioral states. The analysis of olfacto-facial configurations revealed that behavioral markers of disgust (nose wrinkling, upper lip raising) discriminated between some odors judged as being pleasant and unpleasant by adult raters (vanillin vs. butyric acid). However, although some early predisposition to process the affective significance of stimuli may be suggested, no convincing evidence was obtained that neonates discriminated the hedonic valence of odors within the same perceptual space as adults. Finally, neonates evinced a differential pattern of respiratory responding to the presentation of milk odors according to the mode of feeding (breast vs. bottle feeding), suggesting that early olfactory discrimination may be mediated by stimuli with high ecological salience.

[Resonance Raman spectra of transition metal Mn(III), Fe(III), Rh(III), Pd(II) porphyrin complexes]

The resonance Raman spectra of Mn(III), Rh(III), Fe(III), Pd(II) protoporphyrin IX-dimethylester (PP) and tetra-phenylporphyrin (TPP) complexes were reported. The difference of their structure-sensitive band frequency was a result of the interaction of different metal ions' outer d electrons with the electrons of the porphyrin ring. As well the effects of different porphyrin rings and their substituts on the structure-sensitive bands were discussed in this paper.

In vitro lactose fermentation by human colonic bacteria is modified by Lactobacillus acidophilus supplementation

Adaptation of the colonic flora to lactose may contribute to lactose digestion in lactose maldigesters, and supplementation with Lactobacillus acidophilus may modify colonic fermentation of lactose and short-chain fatty acid production. We evaluated the capability of colonic bacteria to ferment lactose and the ability of L. acidophilus to modify lactose fermentation by the colonic microflora in vitro. An anaerobic continuous culture was established and inoculated with fresh samples of human feces. Lactose infusion was maintained at 25 g/d and pH at 6.7. L. acidophilus strain LA-1 (1.5 x 10(10) cells) was introduced into the fermenter on d 0 or added daily on d 0 through 4. The control was the continuous culture without the addition of lactobacilli. Rapid adaptation of colonic bacteria to lactose occurred within 1-2 d, with a significant decrease in lactose concentration and increase in beta-galactosidase activity, and lactose concentrations fell below 3 mmol/L by d 7. Supplementation with strain LA-1 resulted in a significantly greater decrease in lactose concentration and greater increase in acetate and propionate production within the first day compared with the control group. However, there was no significant difference between the fermentation treated with L. acidophilus daily and the control after the first day. These data suggest that the colonic bacteria adapt quickly to lactose, causing efficient utilization of lactose. L. acidophilus supplementation may enhance lactose fermentation during early periods when the adaptation is not established in this model.

Improvement of lactose digestion by humans following ingestion of unfermented acidophilus milk: influence of bile sensitivity, lactose transport, and acid tolerance of Lactobacillus acidophilus

The influence of bile sensitivity, lactose transport, and acid tolerance of Lactobacillus acidophilus on in vivo digestion of lactose was investigated. Four strains of L. acidophilus exhibiting varied degrees of lactose transport, beta-galactosidase activity, and bile sensitivity were used to prepare unfermented acidophilus milks. Lactose malabsorption was evaluated by measuring breath H2 excretion off 11 lactose maldigesting subjects following ingestion of four acidophilus test milks. Test meals were fed in a randomized double-blind protocol. Consumption of acidophilus milk (2% fat) containing strains B, N1, and E significantly reduced mean total H2 production compared with that of the control reduced-fat (2% fat) milk, but milk containing strain ATCC 4356 did not differ from the control. Acidophilus milk containing L. acidophilus N1 was the most effective of the four acidophilus milks in improving lactose digestion and tolerance. Strain N1 exhibited the lowest beta-galactosidase activity and lactose transport but the greatest bile and acid tolerance of the four strains. The results indicated that bile and acid tolerance may be important factors to consider when L. acidophilus strains are selected for improving lactose digestion and tolerance.

Beta 2-adrenergic receptors enhance contractility by stimulating HCO3(-)-dependent intracellular alkalinization

Previous studies established that beta 2-adrenergic receptors enhance the amplitude, without abbreviating the kinetics, of the twitch in adult rat ventricular myocytes. The present study was designed to identify the dominant signaling mechanism mediating this response. Myocytes from adult rat ventricles were loaded with the pH-sensitive fluorophore 2',7'-bis(carboxyethyl)-5(6')-carboxyfluorescein, and simultaneous measurements of intracellular pH and contraction were performed during electrical field stimulation under basal conditions and after stimulation with isoproterenol or the selective beta 2-receptor agonist zinterol. Inhibition of protein kinase A with H-7 completely inhibited the isoproterenol-dependent, but not the zinterol-dependent, positive inotropic response. The effect of zinterol to increase twitch amplitude was associated with an alkalinization of 0.07 +/- 0.02 pH unit, which was not prevented by inhibition of the Na+/H+ exchanger with hexamethylene-amiloride. Rather, removal of bicarbonate from the extracellular buffer prevented the beta 2-receptor-dependent alkalinization as well as the positive inotropic response. These results indicate that beta 2-adrenergic receptors induce a positive inotropic response in adult rat ventricular myocytes via a adenosine 3',5'-cyclic monophosphate-independent mechanism that involves intracellular alkalinization due to activation of a bicarbonate-dependent intracellular pH regulatory mechanism.

Synergies and coincidence requirements between NO, cGMP, and Ca2+ in the induction of cerebellar long-term depression

Parallel fiber synapses onto Purkinje neurons in acute cerebellar slices undergo long-term depression (LTD) when presynaptic activity coincides with postsynaptic depolarization. These electrical inputs can be respectively replaced by nitric oxide (NO) and Ca2+ photolytically released inside the Purkinje neuron, showing that these two messengers are sufficient for LTD induction. NO acts via cGMP production because inhibitors of guanylate cyclase prevent LTD but can be circumvented by photoreleased cGMP combined with Ca2+ elevation. Three inhibitors of cGMP-dependent protein kinase, Rp-8Br-PET-cGMPS, KT5823, and a novel pseudosubstrate peptide, all block LTD. LTD induction permits <10 ms gap between NO release and Ca2+ elevation, whereas 200-300 ms is allowed between uncaged cGMP and Ca2+ increase. This surprising difference in timing precision can be explained either by tighter localization and faster decay of cGMP when generated by NO rather than uncaging, or by two independent coincidence detectors in series.

Functional consequences of acute collagen degradation studied in crystalloid perfused rat hearts

OBJECTIVES

The impact of acute collagen disruption by the disulfide donor, 5,5'-dithio-2-nitrobenzoic acid (DTNB) on ventricular properties was tested in rat hearts.

METHODS

Collagen was degraded acutely in 13 isolated, isovolumically contracting rat hearts by perfusion with 1 mM DTNB added to Krebs-Henseleit solution for 1 hour followed by 2-hour perfusion with normal solution. Another 13 hearts were perfused with normal solution for 3 hours (Control).

RESULTS

Collagen content was 3.5 +/- 0.5% of ventricular dry weight in control group compared with 2.1 +/- 0.4% in DTNB group (decrease by 40%, p < 0.01). Scanning electron micrographs revealed loss of the delicate collagen network surrounding muscle fibers in DTNB treated hearts. Developed pressure at a fixed volume decreased to 86 +/- 17% of the baseline value after 3-hour perfusion in the control group, whereas in DTNB treated hearts developed pressure fell to 68 +/- 13% (p < 0.01). End-diastolic pressure was set at 5 mmHg at the beginning of the experiment and rose to 15 +/- 8 mmHg in control and 30 +/- 13 mmHg (p < 0.01) in the treated hearts. Concomitantly, wet-to-dry weight ratio increased from 5.63 +/- 0.26 in control to 6.07 +/- 0.11 (p < 0.05) in the DTNB treated hearts. A separate set of experiments on isolated myocytes excluded the possibility of a direct effect of DTNB on myocyte contractile function.

CONCLUSIONS

These data suggested that with 40% collagen disruption by DTNB there is a significant increase in tissue edema that results in a decrease in chamber capacitance; in addition, there is a significant decrease in systolic performance which reflects the combined effect of edema and loss of collagen.

[Effects of extract of Cortex Ilicis Rotundae on cardiovascular pharmacology]

In thes paper, the effects of Cortex Ilicis Rotundae (CIR) on Cardiovascular Pharmacology are studied. The results show that ethyl alcohol extract of CIR can reduce coronary blood flow, weaken myocardial contractility, slow down heart rates, prolong survival time of mice and prevent arrhythmias, the roles of CIR decoction are similar to ethyl alcohol extract, but it is not markable on heart rates and myocardial contractility.

Surveillance for polio eradication in the People's Republic of China

A case-based virus surveillance system for wild poliovirus in China was developed. By 1993, all 30 provincial immunization units and, by 1994, all 29 provincial laboratories were sending computerized data to the national level. In 1993, a county-level, computerized map was operationalized that permitted visual monitoring of the progress of the polio eradication program every month by county. In 1993, wild poliovirus type 1 was detected in 8 provinces. Wild poliovirus mainly caused clusters of polio cases identified by a surveillance system that detected primarily clinical polio in children <5 years old (1 stool sample was collected on approximately 50% of reported cases). By 1995, the surveillance system had reached certification-like levels (80% of acute flaccid paralysis [AFP] patients with 2 stool specimens and AFP case rate of 1/100,000 children <15 years old). No indigenous wild poliovirus was detected in 1995. This general case-based model can be applied to measles and other important diseases, and may then lead to a more rapid decrease in adverse health outcomes.

Crystal structure of R-phycoerythrin from Polysiphonia urceolata at 2.8 A resolution

The structure of R-phycoerythrin (R-PE) from Polysiphonia urceolata was determined at 2.8 A resolution. The crystals belong to space group R3 with unit cell dimensions of a = b = 189.8 A, c = 60.1 A. The subunit composition of R-PE is (alpha 2 beta 2)3 gamma. The three-dimensional structure of R-PE was solved by the multiple isomorphous replacement method. After several cycles of model building and refinement, the crystallographic R-factor of the final model is 18.0% with data from 10.0 to 2.8 A resolution. The four phycoerythrobilin chromophores alpha 84, alpha 140a, beta 84 and beta 155 in an (alpha beta) unit are each covalently bound to a cysteine residue through ring A. The phycourobilin chromophore is bound to cysteine beta 50 by ring A and bound to cysteine beta 61 by ring D. The ring A and ring D of phycourobilin deviate from the conjugate plane formed by ring B and ring C and the four rings form a boat-shaped structure. R-PE contains a 34 kDa gamma subunit that is assumed to lie in the central channel of the molecular disc (alpha 2 beta 2)3. The energy transfer and relationship between cysteine residues and chromophores are discussed.

Endovascular embolization of intracranial aneurysms with self-made tungsten coils in a dog model

OBJECTIVE

To evaluate the embolization effects and the long-term histologic changes, including the ultrastructure of the neoendothelium, in experimental canine aneurysms obliterated with self-made tungsten microcoil.

METHODS

Twenty-eight experimental aneurysms were microsurgically created in 14 mongrel dogs by using end-to-side jungular carotid anastomosis. The aneurysms were obliterated with either self-made tungsten microcoil alone or the microcoil plus micro direct current electrocoagulation, with preservation of the parent vessel. The animals were kept in observation. 48 hours, 4 weeks, and 4 months after the embolization of the aneurysms, repeated carotid arteriography was performed to assess the potential recanalization of the aneurysms. The animals were then respectively killed and submitted for autopsy. The carotid artery and the embolized aneurysms were resected and studied with light and electron microscopy.

RESULTS

A total of 14 obliterated aneurysms were completely excluded from the parent circulation by an endothelialized layer of connective tissue. The fundus of the aneurysm was completely obliterated by heavy reactive fibrous tissue surrounding the microcoils with very minimal inflammatory reaction.

CONCLUSIONS

Tungsten microcoils are a relatively ideal embolic material at present for endovascular treatment of aneurysms. Microcoils plus micro direct current electrocoagulation yield more reliable, accurate, and safer embolic effects than microcoils alone for the obliteration of aneurysms.

Proliferation index and vascular density of giant cell tumors of bone: are they prognostic markers?

BACKGROUND

The proliferation index (PI) and vascular density (VD) in giant cell tumors (GCT) of bone were studied to assess then value as prognostic markers.

METHODS

Formalin fixed, paraffin embedded tissue from 7 nonrecurrent (NR-GCT) and 13 recurrent (R-GCT) tumors were stained with MIB-1, a monoclonal antibody against Ki-67 (nuclear proliferation antigen), and QBEND-10, a monoclonal antibody against CD34 (endothelial antigen). A minimum of ten fields/case were analyzed on the SAMBA 4000 Image Analyzer. Only mononuclear cell nuclei were analyzed for MIB-1 staining.

RESULTS

Mean values +/- 1 Standard deviation (SD) for PI (stained nuclear area/total nuclear area) were: NR-GCT, 10.98 +/- 3.70; R-GCT (initial presentation), 8.94 +/- 3.57; and R-GCT (first recurrence), 9.25 +/- 3.52. In addition, the mean PI +/- 1 SD for mononuclear round-ovoid cells was 8.71 +/- 3.47 and was 9.16 +/- 10 for mononuclear spindle cells. The mean values +/- 1 SD for VD (stained area/total area of structures) were: NR-GCT, 10.61 +/- 6.37; R-GCT (initial curettage), 9.40 +/- 4.94; and R-GCT, (first recurrence), 12.56 +/- 5.88. Comparing the means for PI and VD for both groups of tumors using Student's t test showed no statistically significant differences (P = 0.34). In one case of histologically benign GCT that metastasized to the lungs, the PI of the metastatic tissue was not significantly different from the primary tumor.

CONCLUSIONS

This study presents evidence that the degree of tumor cell proliferation and vascularity are not useful parameters to predict the recurrence of GCT of bone and that there are no significant differences between the PI of mononuclear round-ovoid cells and mononuclear spindle cells.

Improvement of lactose digestion in humans by ingestion of unfermented milk containing Bifidobacterium longum

Fifteen lactose malabsorbers were studied to evaluate the effects of consumption of milk containing different strains of Bifidobacterium longum on lactose digestion. Influences of different growth substrates, bile sensitivity, and lactose transport on lactose digestion by bifidobacteria were also investigated. Lactose malabsorption was determined by measuring breath hydrogen excretion of subjects fed four different test milks (three of which contained 5 x 10(8) cfu/ml of B. longum) on 4 different d using a randomized, double-blinded trial. Test milks included 1) 400 ml of lowfat milk (control), 2) 400 ml of milk containing B. longum B6 that had been grown with lactose, 3) 400 ml of milk containing B. longum B6 grown with lactose plus glucose, or 4) 400 ml of milk containing B. longum ATCC 15708 grown with lactose. beta-Galactosidase activity was highest in milk containing B6 grown with lactose but was extremely low in milk containing B6 grown with lactose and glucose. Consumption of milk containing B6 grown with lactose resulted in significantly less hydrogen production and flatulence than occurring after consumption of control milk or the milk containing B6 grown with both lactose and glucose. Hydrogen production after ingestion of 15708 was also significantly lower than hydrogen production after ingestion of the control milk. We concluded that milks containing B. longum might reduce breath hydrogen response and symptoms from lactose malabsorption when the culture is grown in a medium containing only lactose to induce a higher beta-galactosidase level and increase rate of lactose uptake.

Thrombin receptor actions in neonatal rat ventricular myocytes

Previous studies established that thrombin stimulates phosphoinositide hydrolysis and modulates contractile function in neonatal rat ventricular myocytes. The present study further defines the signaling pathways activated by the thrombin receptor and their role in thrombin's actions in cardiac myocytes. The thrombin receptor-derived agonist peptide (TRAP, a portion of the tethered ligand created by thrombin's proteolytic activity) stimulates the rapid and transient accumulation of inositol bis- and tris-phosphates (IP2 and IP3, respectively), which is followed by the more gradual and sustained accumulation of inositol monophosphate (IP1). TRAP elicits a larger and more sustained accumulation of IP1 than does thrombin. Thrombin and TRAP also activate mitogen-activated protein kinase (MAPK) in cultured neonatal rat ventricular myocytes. Differences in the kinetics and magnitude of thrombin- and TRAP-dependent inositol phosphate (IP) accumulation are paralleled by differences in the kinetics and magnitude of thrombin- and TRAP-dependent activation of MAPK. Pretreatment with phorbol 12-myristate 13-acetate (PMA) to downregulate protein kinase C (PKC) attenuates thrombin- and TRAP-dependent activation of MAPK, although small and equivalent effects of thrombin and TRAP to stimulate MAPK persist in PMA-pretreated cells. These results support the notion that the thrombin receptor activates MAPK through PKC-dependent pathways and that the incremental activation of MAPK by TRAP over that induced by thrombin is the consequence of enhanced activation through the PKC limb of the phosphoinositide lipid pathway. TRAP also increases the beating rate of spontaneously contracting ventricular myocytes and elevates cytosolic calcium in myocytes electrically driven at a constant basic cycle length. The effects of TRAP to modulate contractile function and elevate intracellular calcium are not inhibited by tricyclodecan-9-yl-xanthogenate (D609, to block TRAP-dependent IP accumulation) or pretreatment with PMA (to downregulate PKC). The TRAP-dependent rise in intracellular calcium also is not inhibited by verapamil or removal of extracellular calcium but is markedly attenuated by depletion of sarcoplasmic reticular calcium stores by caffeine. Patch-clamp experiments demonstrate that TRAP elevates intracellular calcium in cells held at a membrane potential of -70 mV. Taken together, these results support the conclusion that the thrombin receptor modulates contractile function by mobilizing intracellular calcium through an IP3-independent mechanism and that this response does not require activation of voltage-gated ion channels.

Endothelin-dependent actions in cultured AT-1 cardiac myocytes. The role of the epsilon isoform of protein kinase C

The consequences of endothelin receptor activation were examined in atrial tumor myocytes derived from transgenic mice (AT-1 cells). Endothelin-1 (endothelin) stimulates phosphoinositide hydrolysis in a dose-dependent manner. Endothelin also induces the rapid and transient translocation of protein kinase C (PKC)-epsilon immunoreactivity from the soluble to the particulate cell fraction. The subcellular distributions of PKCalpha and PKCzeta (also expressed by AT-1 cells) are not influenced by endothelin. Using quantitative fluorescence microscopy with fura 2, we examined the effects of endothelin on intracellular calcium. In electrically driven myocytes, endothelin induces a rapid and transient increase in the amplitude of the calcium transient. This is blocked by both phorbol 12-myristate 13-acetate (PMA) pretreatment to downregulate PKC and the PKC inhibitor chelerythrine, arguing that PKCepsilon plays a critical role in endothelin receptor-dependent increases in intracellular calcium. Endothelin also stimulates mitogen-activated protein kinase (MAPK). MAPK activation is markedly attenuated by pretreatment with PMA or pertussis toxin (PTX, to activate susceptible G protein alpha subunits); it is completely prevented by combined pretreatment with PMA and PTX. In contrast, it is not attenuated by chelation of intracellular calcium with BAPTA. These findings indicate that the pathway for endothelin receptor stimulation of MAPK involves PKCepsilon and PTX-sensitive G protein(s). Thus, these studies identify a functional role for PKCepsilon as a mediator of endothelin receptor-dependent increases in cytosolic calcium and MAPK activity in AT-1 cells. Accordingly, the AT-1 cell system should provide a uniquely useful model to identify the intracellular targets for PKCepsilon and investigate their function in the regulation of intracellular calcium homeostasis and the induction of the growth response in cardiac myocytes.

Endovascular embolization with self-made silk segment suspension in a rabbit model

OBJECTIVE

To evaluate the efficacy and the histologic changes caused by self-made silk segment suspension as an agent for endovascular embolization of the external carotid artery of rabbit.

METHODS

Three different silk suspension were used to perform selective endovascular embolization of the external carotid artery in 21 rabbits. Postembolization changes were investigated by angiography, light and electron microscopy, and behavioral and functional examination made in various groups of rabbits.

RESULTS

The vascular changes in the group of simple silk segment were limited. The intima became thinner, while the media and adventitia were intact. However, in groups of ethanol-or estrogen-soaked silk segments, there was evident destruction of all layers of the vascular wall, including the intima, the media and the adventitia.

CONCLUSIONS

Estrogen- or ethanol-soaked silk suspension is ideal and reliable for endovascular embolization, with the former being more effective than the latter. The obliteration caused by the suspension of simple silk segment was due to mechanical packing and compression plus incomplete thrombosis, which is likely to result in recurrence through compensatory collateral circulation.

[Toxicity of cadmium and its mechanism on renal tubular epithelial cells in vitro]

The direct effects of cadmium on the functions and metabolism of renal tubular epithelial cells were observed with radio-immune assay, cytochemical and biochemical methods to study further the mechanism of nephrotoxicity of cadmium. Results revealed uptake of alpha-methyl-D-glucoside (alpha-MG) in renal tubular epithelial cells obviously reduced, outflow of potassium ions increased, c-AMP content reduced and activity of Na+-K+-ATPase was inhibited significantly after exposure to cadmium. Electrochemical gradient of tubular cells maintained by Na+-K+-ATPase played an important role in transference of sodium and glucose, and damage in energy resource system within tubular epithelial cells may be one of the pathogenic mechanisms of kidney injury caused by cadmium. In addition, changes in a group of biological markers and functional enzymes (alkaline phosphatase, AKP; gamma-glutamyltransferase, gamma-GT; lactate dehydrogenase, LDH; glucose-6-phosphate dehydrogenase, G-6-PD; N-acetylglucoside, NAG) were determined in the study, and it was found that they all could reflect better the degree of injury in tubular epithelial cells and their metabolic status and could be used in clinical practice.

The crystal structure of deshexapeptide (B25-B30) insulin at 0.25 nm resolution

The determination of deshexapeptide (B25-B30) insulin (DHI) was divided into two steps. At the first step, the rough structure model of DHI molecule was determined by using the molecular replacement method associated with the molecular close-packing method at 0.30 nm resolution based on the reflection data collected on four-cycle diffractometer. At the second step, the DHI model was adjusted and refined at 0.25 nm resolution based on the data collected on Area Detector. 40 water molecules were determined during the refinement, the final R-factor is 0.185 with R.M.S. deviation of 0.002 nm for bond lengths and 1.9 degrees for bond angles. The differences in conformation and function of DHI with other insulin analogues were compared and discussed.

[Effects of cadmium on calcium homeostasis of isolated epithelial cells of proximal renal tubules]

Changes of intracellular calcium homeostasis in epithelial cell damage of renal tubules caused by cadmium and its relationship with the damage were studied in isolated tubular cells of rabbits. Results showed levels of free calcium (Ca++) in tubular cytoplasm increased significantly with the treatment of cadmium, and a series of cellular ultrastructure were damaged. A calcium channel blocker, phenothiazine, showed blocking and protecting effects on it. This suggested calcium overload played a very important role in kidney damage caused by cadmium.

Eradication of poliomyelitis: progress in the People's Republic of China

China and the other countries of the Western Pacific Region have a goal of eradication of wild poliovirus by the end of 1995. In this report we examine the progress made toward eradication through the end of 1993. We examined the information about poliomyelitis and wild poliovirus based on the acute flaccid paralysis surveillance system. The number of reported poliomyelitis cases decreased from 4623 cases in 1989 and 5065 cases in 1990, which occurred during a large nationwide poliomyelitis epidemic, to 538 cases in 1993. Mass supplemental immunization sessions were conducted during the 1991 to 1992 and 1992 to 1993 winters. After the two rounds of supplemental immunizations in the 1992 to 1993 winter, wild poliovirus was not detected for the subsequent 21 months in 22 contiguous provinces in central and northern China, in which 980 million persons reside. In 1993 wild poliovirus was detected in only 5 provinces in southern China and in 2 provinces in the remote Western region; these provinces have only 14% of the total population in China. China is close to achieving its 1995 poliomyelitis elimination goal. Mass supplemental immunizations in children 0 to 3 years old can rapidly eliminate wild poliovirus from large, very densely populated areas, low income rural areas and remote mountainous areas. There appears to be no technical obstacle, even in the most difficult areas, to achieving global eradication of wild poliovirus by the year 2000.

Mitochondrial Ca2+ overload in primary cultures of rat renal cortical epithelial cells by cytotoxic concentrations of cyclosporine: a digitized fluorescence imaging study

Cyclosporine (CsA) has been reported to disrupt Ca2+ efflux from mitochondria, which suggests that CsA interference with Ca2+ homeostasis may be related to its nephrotoxicity. Therefore, the purpose of this study was (1) to determine intracellular free Ca2+ concentration ([Ca2+]i) and mitochondrial free Ca2+ concentration ([Ca2+]m) after primary cultures of rat renal cortical epithelial cells were exposed to cytotoxic concentrations of CsA; and (2) to explore the role of disruption of intracellular and mitochondrial Ca2+ homeostasis in CsA-induced cytotoxicity. [Ca2+]i in single kidney cells was examined by digitized fluorescence imaging (DFI) of the Ca2+ fluorescent probe, fura-2, and [Ca2+]m in single cells was observed by DFI of fura-2 entrapped in mitochondria after selective permeabilization of plasma membrane and other non-mitochondrial organelles by digitonin. Mitochondrial membrane potential (delta psi) in single kidney cells was examined by rhodamine 123 (Rh-123) with DFI. Intracellular ATP in kidney cells was determined by a HPLC method. CsA resulted in an elevation in [Ca2+]i and [Ca2+]m, dissipation of delta psi and depletion of ATP in a dose- and time-dependent manner. The elevation of [Ca2+]i and [Ca2+]m and depletion of ATP preceded CsA-induced cytotoxicity in kidney cells as measured by lactate dehydrogenase (LDH) leakage. We conclude that CsA-induced alterations in mitochondrial Ca2+ homeostasis and a subsequent loss of energy supply may play a key role in CsA-induced cytotoxicity in primary cultures of rat renal cortical epithelial cells.

Comparison of the hepatotoxicity of toxin T-514 of Karwinskia humboldtiana and its diastereoisomer in primary liver cell cultures

Toxin T-514 of Karwinskia humboldtiana has been demonstrated to be hepatotoxic in vivo and in vitro. Recently a diastereoisomer of T-514 has been isolated. In the present study we have evaluated and compared the in vitro hepatoxicity of the diastereoisomer of T-514 using primary cultures of rat hepatocytes. Cytotoxicity was evaluated by release of cytoplasmic enzyme lactate dehydrogenase (LDH), and mitochondrial metabolic function (MTT reduction). The diastereoisomer was shown to be almost as hepatoxic in vitro as toxin T-514.