New trends in the development of oral antidiabetic drugs

A large number of oral antidiabetic agents are available today. This article provides a short review of the pharmacology and some clinical aspects of various oral antidiabetic drugs. It focuses mainly on the newest developing drugs (therapy of the near future) and on the most commonly used older groups for the common approach of every-day practice (sulphonylureas). The primary goal of this review is to compare the electrophysiological effects of glibenclamide in isolated normal and streptozotocin induced diabetic rats and alloxan induced rabbits ventricular preparations, while on the other hand to differentiate the hypoglycaemic sulphonylureas (0.1-1000 mmol/kg) according to their cardiovascular activity in healthy and diabetic animals. In vitro (1-100 micromol/l) as well as chronically treated (5 mg/kg for 10 weeks) glibenclamide prolonged the action potential duration in normal but failed to affect it in diabetic ventricular preparations. Our results suggest that the sensitivity to glibenclamide of K(ATP) channels in diabetic ventricular fibers is drastically decreased. The effects of different sulphonylureas (tolbutamide, glibenclamide, gliclazide, glimepiride) on ventricular ectopic beats as well as the duration of ventricular fibrillation induced by 10 min ischemia/50 min reperfusion in healthy and diabetic rats were compared. Tolbutamide and gliclazide dose-dependently enhanced both parameters both in healthy and diabetic groups. Glibenclamide in healthy rats increased, while in diabetic rats it decreased the arrhythmogenicity. Glimepiride depressed the arrhythmogenicity in both healthy and diabetic animals. Glimepiride proved to dose-dependently enhance the myocardial tissue flow in dog in contrast to glibenclamide. These results confirm that glimepiride has less cardiovascular actions than other sulphonylureas. From the newest oral antidiabetics this review tries to emphasize the most important basic pharmacological properties, mechanism of action, therapeutic use.     

3H]Dopamine release in striatum in response to cortical stimulation in a corticostriatal slice preparation

A new method has been developed to investigate corticostriatal glutamatergic influence on [3H]dopamine release in striatum in complex corticostriatal slice preparation in vitro. Horizontal slices containing the striatum and the adjacent prefrontal cortex of rat brain were cut in a plane that maintains corticostriatal connections. After incubation with [3H]dopamine, slices were submerged in a two-compartment bath so that the cortical region was contained entirely in one compartment, corpus callosum passed through a silicone greased slot, and the striatal region was contained in the other compartment. A cannula was placed just above the striatal part of the slice and effluent was collected with a peristaltic pump, released tritiated materials were counted with a liquid scintillation counter. Electric field stimulation of cortex increased the release of [3H]dopamine in the striatum. Bicuculline (1 mM) increased the basal and stimulated release of [3H]dopamine in the striatum in response to cortical stimulation of cortex indicating the GABAergic control on dopamine release. This method allows investigation of the effect of cortical stimulation on glutamate-dopamine-GABA interactions in the striatum in vitro that might help to understand better the neurochemical background of schizophrenia or Parkinson's disease.     

Dalteparin sodium treatment during resuscitation inhibits hemorrhagic shock-induced leukocyte rolling and adhesion in the mesenteric microcirculation

BACKGROUND: Ischemia/reperfusion-induced polymorphonuclear neutrophil leukocyte (PMN) adhesion and extravasation are pivotal for the development of postinjury multiple organ failure. We hypothesized that the deleterious microcirculatory consequences of hemorrhagic shock (HS) could be altered by low-molecular-weight heparin (LMWH) therapy. Our aim was to investigate the effects of dalteparin sodium on leukocyte-endothelial cell interactions when LMWH treatment was initiated before HS or during resuscitation. METHODS: Anesthetized dogs underwent HS (40 mm Hg mean arterial pressure for 60 minutes) and resuscitation either with shed blood or with lactated Ringer's (LR) solution. LMWH or conventional heparin sodium pretreatment was administered subcutaneously before hemorrhage; or LMWH was given intravenously during resuscitation. Mesenteric postcapillary venules were observed by intravital video microscopy before and after HS, and 60 minutes, 120 minutes, and 180 minutes after resuscitation, and leukocyte rolling and firm adherence were determined. RESULTS: HS significantly increased PMN rolling and adhesion in the mesenteric microcirculation. LMWH, but not heparin sodium pretreatment, significantly inhibited both primary and secondary interactions. LMWH treatment was also effective when initiated during resuscitation. LMWH exerted the same inhibitory effect regardless of the type of resuscitation. CONCLUSION: LMWH treatment during resuscitation effectively inhibits PMN rolling and adhesion.     

Popliteal traumatic arteriovenous fistulas

BACKGROUND: The purpose of this report is to analyze the clinical presentation, diagnosis, and outcome of surgical treatment in patients with popliteal arteriovenous fistulas (AVFs) in order to make trauma surgeons aware of the various issues patients with popliteal AVFs might present. METHODS: From 1991 to 2000, 49 patients were treated for traumatic AVF. Among these patients, seven suffered from popliteal AVF of various durations. The patients were men and ranged in age from 17 to 27 years, with a mean age of 22.4 years. The time from injury to admission to our institutions varied from 5 days to 2 years. A diagnosis of popliteal AVF was made after clinical examinations revealed thrill and bruit over the injury sites. The diagnosis was confirmed in four of the patients after they underwent angiography. Patients with long-standing popliteal AVF underwent cardiology examinations to check for signs of heart failure. All patients with popliteal AVF received surgical treatment. Five patients had major blood vessels reconstructed, one patient had a minor blood vessel ligated, and another patient had a minor blood vessel reconstructed. RESULTS: Five of the seven patients experienced no postoperative difficulties. No serious heart failure occurred; however, there were signs of cardiac overload in three of the five patients. The two remaining patients of the seven underwent leg amputations. However, one of the two patients had a gangrenous foot at admission to our institution, and vascular reconstruction on the other patient was unsuccessful. For all seven patients, the average hospital stay in the vascular surgery department was 16.2 days and the follow-up ranged from 2 to 44 months, with a mean of 21.5 months. CONCLUSION: Trauma of the popliteal space requires special attention, since blood vessel injuries in that zone might result in serious complications. Popliteal traumatic AVFs result in a high rate of leg amputation and long-standing fistulas produce cardiac overload. The presence of thrill and bruit over the injury site should alert the examiner to consider the existence of AVF. Angiography is a reliable diagnostic tool, and should be used in all vitally stable patients. Surgical or nonsurgical closure of AVF will prevent local and systemic complications that might be irreversible in long-standing fistulas.     

Late reconstructive surgery for cloaca malformations

The rarity of cloacal anomalies, the wide range of anatomical variants, and the number of different operations mean that successful management of a patient (neonate or child) with this condition is one of the greatest challenges for paediatric surgeons. The authors describe the complex corrections of 3 patients with cloacal malformation (age 10-13 years). The cloacal malformations were not diagnosed at neonatal age and therefore only the anorectal agenesis was corrected at the first stage. The authors strongly recommend that all components of this anomaly (urethra, vagina and anorectum) should be managed in one step. Because of the rarity and complexity of cloacal malformations, the anomaly should be operated on only in specialised centres.     

Results of mammographic screening at the Mammary Center of Debrecen in 1999 and 2000

INTRODUCTION: The screening mammography decreases the mortality of female breast cancer. METHODS: A complex, independent centre of screening mammography has been operating in Debrecen since 1999. RESULTS: The number of the examinations were 10,399 in 1999 and 13,800 in 2000. The number of explored breast cancer cases were 43 (0.41%) in 1999 and 62 (0.45%) in 2000. CONCLUSION: Although the mortality reduction can be exactly measured after several years, we are convinced that the chances for a better life of these 107 women operated on with breast cancer in early state increased thanks to our project. The results of the breast cancer screening program in Debrecen fulfilled the professional requirements of mammographic service-screening.     

In vitro antioxidant properties of pentoxifylline, piracetam, and vinpocetine

Oxygen-free radicals play an important role in several physiologic and pathophysiologic processes. In pathologic circumstances, they can modify and damage biologic systems. Because oxygen-free radicals are involved in a wide range of diseases (cerebrovascular, cardiovascular, etc.), scavenging these radicals should be considered as an important therapeutic approach. In our in vitro study, we investigated the antioxidant capacity of three drugs: pentoxiphylline (Sigma Aldrich, St. Louis, MO, USA) piracetam (Sigma Aldrich), and vinpocetine (Richter Gedeon RT, Budapest, Hungary). Phenazine methosulphate was applied to generate free radicals, increasing red blood cell rigidity. Filtration technique and potassium leaking were used to detect the cellular damage and the scavenging effect of the examined drugs. According to our results, at human therapeutic serum concentration, only vinpocetine (Richter Gedeon RT) had significant (p < 0.01) scavenging activity with a protective effect that increased further at higher concentrations. Pentoxiphylline (Sigma Aldrich) and piracetam (Sigma Aldrich) did not have significant antioxidant capacity at therapeutic concentrations, but increasing their concentrations (pentoxiphylline at 100-times, and piracetam at 10-times higher concentrations) led to a significant (p < 0.01) scavenger effect. Our findings suggest that this pronounced antioxidant effect of vinpocetine and even the milder scavenging capacity of pentoxiphylline and piracetam may be of value in the treatment of patients with cerebrovascular disorders, but merits further investigations.     

Oestrogen-dependent tracing in the rat CNS after pseudorabies virus infection

This study examines the hypothesis that neuronal infectivity and the spreading of the pseudorabies virus (PRV) through the synapses in the central nervous system (CNS) are influenced by the oestrogen levels. The arcuate nucleus (ARC) and the subfornical organ (SFO) were chosen as models for analysis; the neurons in both structures possess oestrogen receptors and are mutually connected. A genetically engineered pseudorabies virus (Ba-DupLac) was used as a transneuronal tract tracer. This virus is taken up preferably by axon terminals, and transported very specifically through the synapses in a retrograde manner. Ba-DupLac was injected into the ARC of rats, followed by monitoring of the PRV-immunoreactivity (PRV-IR) in the SFO 72 h following inoculation. We found no PRV immunolabelling in the SFO of ovariectomized (OVX) rats, or in those OVX animals that received oestrogen shortly (4 h) before PRV infection (OVX + E 4 h). In contrast, in those OVX animals that received oestrogen 12 h before PRV infection (OVX + E 12 h), and also in intact control animals, PRV-IR was demonstrated in the SFO in all cases. Surprisingly, a reverse labelling was observed in the OVX rats; PRV-IR appeared in the pyriform cortex, whereas PRV-IR could not be detected in the control and OVX + E 12 h animals. As far as we are aware, this is the first study to demonstrate that transneuronal PRV labelling depends on the effects of oestrogen on certain CNS structures and connections.     

Short-term hypobaric hypoxia enhances visual contrast sensitivity

The effect of hypoxia on early visual functions remains a controversial area of research. To explore this question, we measured static and dynamic visual contrast sensitivity in 14 healthy volunteers at a simulated altitude of 5500 m. In comparison with the baseline condition (mean arterial oxygen saturation: 98.4%), contrast sensitivity significantly increased after 5, 10 and 15 min of hypoxic exposure (saturation: 82.9%, 77.0%, 74.3%, respectively). After 10 min, this enhancement was markedly pronounced under dynamic conditions. Returning to the baseline altitude (saturation: 97.7%), contrast sensitivity recovered, mostly at the lower spatial frequencies. There was a significant negative relationship between arterial oxygen saturation and contrast sensitivity values at low and medium spatial frequencies (0.5-4.8 c/deg). These results suggest that early visual processing may be enhanced during short-term hypoxic challenge.