Cardioprotective effect of the Hibiscus rosa sinensis flowers in an oxidative stress model of myocardial ischemic reperfusion injury in rat

Background  

The present study investigates the cardioprotective effects of Hibiscus rosa sinensis in myocardial ischemic reperfusion injury, particularly in terms of its antioxidant effects.     

Management of chylous ascites following laparoscopic presacral neurectomy

Chylous ascites is an extremely rare complication of laparoscopic presacral neurectomy (LPSN), and treatment is still controversial. Four patients undergoing LPSN for dysmenorrhoea or chronic pelvic pain were complicated with chylous ascites. Two were successfully treated with bipolar cauterization and one, after the failure of initial treatment by bipolar cauterization, was then effectively managed by compression with Gelform and closure of the peritoneum of the presacral area by suture through laparoscopy. The fourth patient had persistent chyle leakage from the drainage tube after electrocauterization and was finally cured by conservative management including removal of the drainage tube and a low-fat diet for 3 weeks. Chylous ascites has not been reported in laparoscopic presacral neurectomy. Management that is quick, effective and subjects the patients to the least amount of suffering is still unresolved. Repeated laparoscopy can be considered to identify the possibility of injury to lymphatic vessels, to relieve abdominal distention due to chyle accumulation, and to apply electrocauterization or compression with Gelform and closure of the peritoneum. Conservative treatment with a low-fat diet may need a longer time. The use of a drainage tube may provide negative pressure allowing a continuous leakage of chyle. However, more controlled study is required to identify the most proper and effective management.      

The von willebrand factor domain-mediating botrocetin-induced binding to glycoprotein IB lies between Val449 and Lys728

Botrocetin, a component of Bothrops jararaca venom, induces von Willebrand factor (vWF)-dependent platelet agglutination and has been proposed as an alternative agent to ristocetin for evaluating vWF function. However, important differences between the vWF-platelet interactions induced by these two agents have suggested that different regions of vWF and the platelet may be involved in the interactions induced by the two agonists. We have recently demonstrated that binding of vWF to the platelet glycoprotein (GP) Ib receptor, either induced by ristocetin or as occurs spontaneously with asialo-vWF or vWF from IIb von Willebrand disease, is mediated by a domain residing on a 52/48- kilodalton (kD) tryptic fragment of vWF. This fragment extends from amino acid residue Val (449) to Lys (728). We have now found that this 52/48-kD fragment blocks botrocetin-induced binding of vWF to platelets and completely inhibits botrocetin-induced platelet agglutination. These results provide evidence that the vWF domain-mediating, botrocetin-induced platelet agglutination lies within the region delimited by this fragment and is therefore close to or identical with that which mediates ristocetin-induced binding and spontaneous binding of vWF to platelet GPIb. Anti-GPIb monoclonal antibodies also blocked agglutination, which showed that botrocetin, like ristocetin, induces binding of vWF to the GPIb receptor.     

Synergistic effects of butyrate on platelet responses to arachidonate, A23187, PGE1, and forskolin

With eukaryotic cells, butyrate is known to induce a series of morphological and biochemical changes that mimic cellular differentiation. With platelets, we have found that butyrate (10 mmol/L) caused an approximately threefold increase in sensitivity to calcium ionophore A23187 and arachidonate. Maximum aggregation was observed at agonist concentrations of 3 mumol/L and 170 mumol/L, respectively, as compared with required concentrations of 10 mumol/L and 400 mumol/L in the absence of butyrate. Similar effects were seen with isobutyric acid, and about one-half the effect was shown with valerate and caproate, but lower homologues showed no synergistic effect. No ultrastructural changes were observed in platelets incubated with butyrate, and the aggregation effects were reversible and returned to normal on removal of butyrate. Membrane fluidity was unchanged by butyrate as measured by changes in the fluorescence depolarization of diphenylhexatriene. Butyrate caused a 60% to 70% increase in the uptake of 3H-arachidonate. Butyrate also potentiated the inhibition of platelet function by prostaglandin E1 and forskolin and uptake of 3H- forskolin was increased approximately 20%. In contrast, platelet response to other agonists (ADP, epinephrine, collagen, thrombin, and platelet-activating factor) was essentially unaffected by butyrate. These results suggest that butyrate may increase the uptake of certain hydophobic agonists and antagonists by platelets. Similar mechanisms for uptake of endogenous effectors may explain the response of eukaryotic cells to butyrate in culture.     

Management of Nucleus and IOL Drop

Background

Thirty six cases of lenticular nucleus drop following phacoemulsification and 43 cases of posterior dislocation of intraocular lens (IOL) inclusive of two paediatric cases were managed by a modified vitrectomy procedure without using perfluorocarbon liquid (PFCL).

Methods

In these cases the incision was placed inferotemporally at pars plana. The limbal sites of the earlier cataract surgery were utilised as the other two ports. In either case adequate vitrectomy was performed first. In cases of nuclear drop, the nucleus was impaled (speared) with a micro vitreo retinal blade and brought into the anterior chamber from where it was delivered out. In cases of IOL drop the same was picked up by an intra-vitreal forceps.

Result

Of the 77 adult cases treated 57 (74%) of the eyes had a visual recovery of 6/18 or more.

Conclusion

Prompt surgical management in cases of nuclear drop or posterior dislocation of IOL yields good results.Key Words: Phaco-emulsification, Intraocular lens drop, Nucleus drop, Vitrectomy     

Evidence that calpains and elastase do not produce the von Willebrand factor fragments present in normal plasma and IIA von Willebrand disease

Recent evidence suggests that proteolysis plays an important role in some forms of inherited and acquired von Willebrand disease (vWD). Because calpains and one or more enzymes released from polymorphonuclear leukocytes are known to proteolyze von Willebrand factor (vWF) in vitro with resultant loss of large multimers similar to that seen in IIA vWD, they have been suggested as being responsible for the proteolysis in vivo. Using monoclonal epitope mapping, we have examined the proteolysis of the vWF subunit by porcine calcium- activated neutral proteases (calpains) and human leukocyte elastase to determine whether they produce the vWF proteolytic cleavage products seen in normal individuals and IIA vWD. Purified vWF was digested with porcine calpains I and II. We found no difference in the size, location, and quantity of the fragments produced by calpain I v calpain II. New fragments were detected of approximately 200, 170, 150, and 125 Kd. There was no evidence for generation of the native 140 and 176 Kd fragments. Some loss of the native fragments was seen, which suggests that they were further cleaved. Epitope mapping of the 170- and 150-Kd calpain-cleaved fragments revealed them to be from different parts of the molecule than the regions from which the native 176- and 140-Kd fragments derived. This was further supported by determination of the amino-terminal sequence of the calpain-cleaved 170- and 150-Kd fragments. Digestion of vWF with human leukocyte elastase produced new fragments at 210/205, 190, 170/165, 145/140, and 130/125 Kd. No generation of native fragments was detected. Monoclonal epitope mapping of the 145/140-Kd elastase-cleaved band proved that it derived from the carboxyl-terminal portion of the vWF molecule, whereas the native 140- Kd fragment is derived from the amino-terminal end. Neither calpains nor human leukocyte elastase produced the proteolyzed fragments present in normal and IIA vWD and, therefore, probably do not cause the loss of large multimers that is seen in that disorder.     

Switching of the nonallelic forms of fetal hemoglobin during late gestation

The gamma chains of human fetal hemoglobin occur in two nonallelic forms, designated G gamma and A gamma, which differ from one another in having either glycine or alanine as their 136th residue respectively. In newborns, G gamma comprises about 75% of the total gamma chains, while in adults, G gamma comprises about 40% of the total gamma chains. The timing of the switching events that lead to the alteration of the rates of production of G gamma and A gamma are still unknown. Umbilical cord red blood cells from term infants were separated by density gradient fractionation into four age-dependent fractions. Red blood cell size and reticulocyte content decreased and the percent fetal hemoglobin increased with increasing gradient densities, confirming age- dependent density separation. The percent G gamma was determined by two methods on fractionated cord red blood cells to determine if the switch in the production ratio of the nonallelic forms of gamma chains began during late gestation. The G gamma content of fetal hemoglobin was found to decrease with decreasing red blood cell age, demonstrating that the switch from predominately glycine-containing gamma chains to predominately alanine-containing gamma chains begins during late gestation.     

Proteolytic degradation of von Willebrand factor after DDAVP administration in normal individuals

The infusion of 1-deamino-8-D-arginine vasopressin (DDAVP) in normal individuals is followed by an increase in factor VIII/von Willebrand factor (vWF) in plasma, by an increase in intensity of all sizes of multimers, and by the appearance of larger multimers of vWF than those seen in the resting state. Since the larger multimers are rapidly cleared and proteolysis is known to cause disaggregation of large multimers, we evaluated the degree of vWF proteolysis after DDAVP administration. DDAVP was infused into eight normal adult volunteers, and the relative proportions of the intact 225 kilodalton (kDa) subunit and the 189, 176, and 140 kDa vWF fragments were compared before and at different times after DDAVP infusion. The relative proportion of the 176 kDa fragment was increased, whereas that of the other species was decreased, thereby indicating that proteolytic fragmentation had occurred. However, plasmin did not appear to be responsible because the vWF fragments characteristically produced by this enzyme could not be detected. Concomitant analysis of vWF multimeric structure showed that these changes were accompanied by an increase in the relative proportion of the satellite bands, which suggests that they were proteolytically generated. Proteolysis may explain, at least in part, rapid clearance of larger vWF multimers released by DDAVP.     

High-resolution analysis of von Willebrand factor multimeric composition defines a new variant of type I von Willebrand disease with aberrant structure but presence of all size multimers (type IC)

In Type I von Willebrand disease, the whole series of von Willebrand factor (vWF) multimers is present in plasma, but all are decreased in quantity. No structural abnormality of individual multimers has been demonstrated so far in these patients. We now describe five individuals, from two unrelated families, who had this form of the disease and in whom the complex banding pattern of each vWF multimer was markedly abnormal. Inheritance was autosomal dominant and the clinical expression was mild. A bleeding history was elicited in three of the patients and included recurrent epistaxis, menometrorrhagia, and bleeding following tooth extraction. Replacement therapy had never been required. Although vWF levels in plasma were within the normal range in all of them, the ristocetin cofactor activity was decreased in four, and the bleeding time was prolonged in three. Analysis of vWF multimeric structure by agarose gel electrophoresis, including a newly developed high-resolution technique, demonstrated that the main band of each multimer was present, but a second, well-defined band always seen in normal individuals was missing in the patients. Two additional bands had altered mobility and were less well defined than in normal subjects, and a fifth, less intense band was also undetectable in the patients. Treatment with 1-deamino-8-D-arginine vasopressin (DDAVP) was assessed in two patients. It caused the circulating levels of vWF to increase and correct the bleeding time, but did not alter the structural abnormality. This study describes, therefore, a new variant form of Type I von Willebrand disease with aberrant structure of individual repeating multimers and an associated functional abnormality of vWF. In keeping with previously accepted terminology, the designation of Type IC von Willebrand disease has been adopted for this new variant.     

Type IIB von Willebrand's disease: differential clearance of endogenous versus transfused large multimer von willebrand factor

The abnormal multimeric composition of plasma von Willebrand factor in type IIB von Willebrand's disease is transiently corrected after infusion of 1-deamino-[8-D-arginine]-vasopressin. However, the larger multimers released into the circulation disappear more rapidly in these patients than in type I von Willebrand's disease or normals. We demonstrate that the larger multimers of normal von Willebrand factor transfused into a type IIB patient are cleared from the circulation more slowly than multimers of similar size endogenously released from tissue stores. The rate of disappearance of large von Willebrand factor multimers after infusion of cryoprecipitate is similar in IIB, IIA, and severe homozygous-like von Willebrand's disease. Platelets from the IIB patient exhibited normal ristocetin-induced binding of normal von Willebrand factor. However, like normal platelets, they bound IIB von Willebrand factor at lower ristocetin concentrations than required for normal von Willebrand factor. These findings provide evidence that absence of the larger multimers from IIB plasma is related to a molecular abnormality of von Willebrand factor rather than to enhanced affinity of abnormal tissue or cellular binding sites, as is the case in the recently described "pseudo" von Willebrand's disease and "platelet-type" von Willebrand's disease.