Effects of the neuropeptide thyrotropin-releasing hormone on GABAergic synaptic transmission of CA1 neurons of the rat hippocampal slice during hypoxia

Because thyrotropin-releasing hormone (TRH) has been suggested to improve recovery of brain neurons from hypoxia, which strongly impairs GABAergic synaptic transmission, the present electrophysiological study used intracellular recording from CA1 neurons of the rat hippocampal slice to examine the cellular mechanisms underlying this phenomenon. Hypoxia induced by superfusion with a medium devoid of oxygen evoked typical membrane hyperpolarization, fall in input resistance, and strong depression of monosynaptic, GABAA receptor-mediated fast inhibitory postsynaptic potentials (IPSPs). The depression of fast IPSPs during hypoxia was found to be due to a combination of factors such as shift in the IPSP reversal potential and membrane hyperpolarization. GABAB receptor-mediated slow IPSPs were comparatively less sensitive to hypoxia. TRH (10 microM), applied 1 min prior to hypoxia, selectively accelerated recovery of membrane potential and delayed return of fast IPSPs to control amplitude without changing the mechanisms responsible for depression of GABAergic transmission. In conclusion, despite a slower recovery of IPSPs, TRH facilitated earlier return of neuronal excitability after the hypoxic period.

Ifosfamide and vinorelbine as first-line chemotherapy for advanced non-small cell lung carcinoma

We evaluated the efficacy and toxicity of the novel combination of ifosfamide (IFX) and vinorelbine (VNB) as first-line chemotherapy in patients with stage IIIB and IV non-small cell lung cancer (NSCLC). Between March 1993 and November 1994, 44 patients (17 stage IIIB; 27 stage IV) received a regimen consisting of IFX, 2 g/m2 in a 1-h infusion, days 1-3; mesna, 400 mg/m2 in an i.v. bolus at hours 0 and 4 and 800 mg orally at hour 8, days 1-3; and VNB, 35 mg/ m2 in a 20-min infusion, days 1 and 15. During the first course only, a half dose of VNB (17.5 mg/m2) was administered on days 8 and 22. Courses were repeated every 28 days. Forty patients were fully evaluable for response, and 44 were assessable for toxicity. Objective regression was recorded in 13 of 40 patients (33%). No patient achieved a complete response. Thirteen patients presented a partial response (33%); 17 (42%) had no change; and progressive disease was observed in 10 (25%). The median duration of response was 10 months, and the median time to treatment failure for the whole group was 4 months. Median survival was 11 months. The dose-limiting toxic effect was myelosuppression. Leukopenia occurred in 25 patients (57%) and was grade 3 or 4 in 8 patients (18%). Twelve patients (27%) developed peripheral neurotoxicity, while five had mild IFX-induced CNS toxicity. Phlebitis was observed in 15 of 30 patients (50%) who did not have central implantable venous systems. The IFX-VNB combination exhibited an activity against NSCLC that was among the highest reported for non-cisplatin-containing regimens, with a toxicity profile that was easily managed.

Occurrence and properties of the hyperpolarization-activated current If in ventricular myocytes from normotensive and hypertensive rats during aging

BACKGROUND

Cellular electrophysiological alterations may contribute to arrhythmogenesis in cardiac hypertrophy. An L-like current occurs in left ventricular myocytes (LVMs) isolated from the hypertrophied heart of old spontaneously hypertensive rats (SHR). Factors that influence L occurrence during development of cardiac hypertrophy were studied by determining its presence, amplitude, characteristics, and beta-adrenoceptor modulation.

METHODS AND RESULTS

Patch-clamped LVMs from young (2 to 3 months old) or old (18 to 24 months old) normotensive Wistar-Kyoto rats (WKY) and SHR were used. A diastolic depolarization phase was present in old SHR. An If-like current occurred in > 90% of LVMs from old SHR and WKY and in approximately = 15% of LVMs from young rats (P < .05). Activation curves of If were similar in old rats, with the midpoint at -92.9 +/- 2.9 mV in WKY (n = 42) and -88.1 +/- 1.5 mV in SHR (n = 25); maximal specific conductance was 54.4 +/- 1.7 in SHR and 20.1 +/- 0.5 picosiemens/picofarad in WKY (P < .05). In WKY, If amplitude was linearly related to membrane capacitance, an index of cell size (r = .53, P < .001). This relation was absent in SHR, in which a significant positive correlation was found between the heart weight to body weight ratio and I(f) density. In both old WKY and old SHR, 0.1 mumol/L (-)-isoproterenol increased I(f) amplitude by shifting its activation curve toward more positive potentials.

CONCLUSIONS

In LVMs from both WKY and SHR, the occurrence of I(f) increases with aging. Density appears linearly related to the severity of cardiac hypertrophy and increases with beta-adrenoceptor stimulation, which suggests that I(f) may contribute to an increased propensity of the hypertrophied heart for arrhythmias.

Nuptiality, fertility, use of contraception, and family policies in Uzbekistan

With more than 22 million inhabitants, Uzbekistan is the most populous of the Central Asian republics of the former USSR. Using data from a retrospective survey conducted in 1992 among women of reproductive age, the paper examines fertility trends and determinants during the twentieth century. The analysis shows that the absence of a government-supported birth control programme and the strong pro-natalist policies of the Soviet authorities during most of the century did not affect either the onset, nor the progress of the fertility transition. The results indicate, however, that the social development programmes undertaken by the Soviet government did play a very active part in the transition as shown by the impact of education on reproductive behaviour, as well as on the very specific contraceptive mix adopted by the population after the mid-1970s.

Beta-adrenoceptor subtypes in young and old rat ventricular myocytes: a combined patch-clamp and binding study

1. We used electrophysiological and binding techniques to assess the presence of beta 1- and beta 2-adrenoceptors (beta 1AR and beta 2AR) in rat cardiac myocytes and to determine their ratio during aging. Experiments were performed in left ventricular myocytes enzymatically dissociated from the heart of 3-(young) or 22-month-old (old) Wistar Kyoto rats. 2. In patch-clamp experiments, myocytes from old rats showed a prolonged action potential duration (at -20 mV: 41.7 +/- 3.6 vs 26.2 +/- 3.1 ms; at -60 mV: 154.4 +/- 17.7 vs 87.1 +/- 6.9 ms, P < 0.05) and an augmented membrane capacitance (an index of cell size) (271.7 +/- 20.2 vs 164.3 +/- 14.6 pF, P < 0.05) compared to young rats. beta 2AR stimulation, achieved by superfusing myocytes with the selective beta 2AR agonist, zinterol (10 microM) or with (-)-isoprenaline (1 microM) in the presence of the selective beta 1AR antagonist, CGP 20712A (0.1 microM), significantly increased L-type calcium current (ICa,L) in rat ventricular myocytes. The percentage increase was similar in both young and old rats, either with zinterol (26.9 +/- 3.6% and 24.2 +/- 2.8%, respectively) or isoprenaline plus CGP 20712A (30.4 +/- 3.7% and 22.4 +/- 4.1%, respectively). Isoprenaline alone (beta 1AR and beta 2AR stimulation) caused a much smaller increase in ICa,L in old rats (58.4 +/- 12.1%) than in younger ones (95.3 +/- 8.1%) (P = 0.067). 3 The number of ,BAR mg-' protein, measured with saturation binding assays of the non selective ,betaAR antagonist [3H]-CGP 12177 was 1989.4+/-189.5 for 3- and of 1580.7 +/-161.5 for 22-month-old rats.Competition for [3H]-CGP 12177 binding by CGP 20712A gave biphasic curves which demonstrated two classes of binding sites. Densities (as percentages of total PAR density), and affinities for the two binding sites were: 80.4 +/- 2.2% (Ki = 6.6 +/- 1.3 nM) betaAR and 19.6 +/- 2.2% (Ki = 6.9 +/- 2.2 microM) beta2AR in young rats and 66.1 +/- 1.2% (Ki=8.3+/- 1.1 nM) beta1 AR and 33.9+/- 1.2% (Ki=5.2+/-0.6 PM) P2AR in old rats. Thebeta1AR/beta2AR ratio was significantly (P<0.01) reduced in old rats with respect to the younger ones.4 By combining electrophysiological and binding measurements, we calculated beta1AR and beta2ARdensities as number of receptors per microM2 of cell surface. In old rats, beta1 density was significantly decreased compared to young rats (8.4+/-2.0 vs 15.4+/-3.7 receptors microM-2, P<0.05), while beta2AR density remained unchanged at both 3 and 22 months (3.8 +/- 0.7 and 4.2+/-1.1 receptors microM-2, respectively).5 Our results demonstrate that both beta1AR and beta2AR are functionally present in rat ventricular myocytes of young and old rats. The decreased responsiveness to betaAR stimulation during aging appears to be associated with a selective reduction in the density of beta1AR.

In vivo cell kinetics in head and neck squamous cell carcinomas predicts local control and helps guide radiotherapy regimen

PURPOSE

To determine whether pretherapy cell kinetics can predict local control for patients affected by head and neck squamous cell carcinomas (HN-SCCs) to be treated by primary radiotherapy and, moreover, guide to a choice between conventional and accelerated radiotherapy.

PATIENTS AND METHODS

Between 1989 and 1993, 83 patients with stage II to IV HN-SCC entered the study. Multiple primary tumor biopsies were obtained 6 hours after in vivo infusion of bromodeoxyuridine (BrdUrd). In vivo S-phase fraction labeling index (LI), duration of S phase (Ts), and potential doubling time (Tpot) were obtained by analysis of multivariate flow-cytometric data. Between April 1989 and January 1991, 49 patients were treated by conventional radiotherapy (70 Gy in 35 fractions over 7 weeks), whereas, afterwards, 34 patients entered an accelerated radiotherapy regimen with the concomitant boost technique (75 Gy in 40 fractions over 6 weeks).

RESULTS

Univariate analysis showed that, among patients treated by conventional radiotherapy, local control probability was affected by tumor stage (P = .02), Tpot (P < .001), and LI (P = .04). Similarly, among patients treated with accelerated radiotherapy, we found that local control probability was related to tumor stage (P = .03) and primary tumor site (P = .05). For the subgroup of patients with tumors characterized by fast growth (Tpot < or = 5 days), accelerated radiotherapy gave a better local control rate than conventional radiotherapy (P = .02). Cox multivariate analysis of the total number of patients showed that the only significant independent prognostic factors related to local control were tumor stage (P = .002) and Tpot (P = .004). Moreover, when the Cox analysis was restricted to the subgroup of patients treated with conventional radiotherapy, Tpot was the most significant factor to predict local outcome (P < .01).

CONCLUSION

Pretreatment tumor Tpot appears to be an important independent prognostic factor for local control of HN-SCC treated by primary radiotherapy.

[Odontogenic sinusitis with cutaneous fistulization. A case report]

A 70-year-old male patient presenting with a cutaneous node of the genal region that was first diagnosed as basal cell carcinoma is described. Owing to the following observation, the authors were prompted to a diagnosis of cutaneous odontogenic sinusitis: a) examination of the lesion which emitted pus upon gentle squeezing; b) presence in the vestibular fornix of a large fibrous cord; c) the serious conditions of the mouth and the radiologic results of homolateral sinusitis. The importance of the sinusitis picture, and the necessity to completely remove all bacteria foci prior to surgery on the abdominal aorta the patient was scheduled to undergo, prompted the authors to avulse the cutaneous lesion with tooth extraction, after a "Caldwell-Luc" operation of the homolateral paranasal sinus. Full restitutio ad integrum was achieved.

Synthesis of N1-substituted benzamidines. Effects on blood coagulation, platelet aggregation and antiarrhythmic activity

A series of N1-substituted-4-alkoxybenzamidines was synthesized and tested in vitro for their inhibitory effects on blood coagulation and agonist induced platelet aggregation. The antiarrhythmic activity against chloroform-induced arrhythmias in mice was also evaluated. The biological activity of the title compounds is reported in comparison with that of procainamide; among the new products described, IVi and IVe were found to have the most potent anti-platelet and antiarrhythmic activity, respectively. The structure-activity relationships are discussed.

Cell stress and ribosome crystallization

New methods of inducing ribosome crystals in chick embryos are described, and it is shown that a close relationship exists between cell stress and ribosome crystallization. The formation of ribosome crystals in the nucleus and/or in the cytoplasm depends on the type of treatment and on the temperature of incubation, but in all cases the key event that produces crystallizable ribosomes appears to be a damage to the ribosome transport system. This prevents the movement of messenger-free ribosomes towards their destination sites, and accumulates a pool of potentially crystallizable ribosomes in restricted areas of the cell. This mechanism accounts for the fact that ribosome crystallization occurs in chick embryos in the widely different conditions such as those induced by cooling, anoxia, heat-shocks and programmed cell death.

Cellular electrophysiological aspects of myocardial protection

Oxygen radicals (OR) generated at the time of reflow of the ischaemic myocardium may cause 'reperfusion injury'. To protect myocardium from this injury, it is important to understand how OR cause their deleterious effects on myocytes. Here we describe the basic electrophysiological alterations caused by OR in patch-clamped ventricular myocytes isolated from the rat heart. Oxygen radicals generated by dihydroxyfumarate (DHF) caused a lengthening of action potential duration (APD) and the appearance of arrhythmogenic alterations such as early and delayed afterdepolarizations. Prolongation of APD was accompanied by a reduction in calcium and potassium currents. When intracellular calcium levels were kept constantly low by 500 microM EGTA in the pipette solution, the effects of DHF on action potential duration and the occurrence of early afterdepolarizations were largely prevented. It is concluded that exposure to OR may induce electrophysiological alterations in isolated myocytes. They are related to changes in specific ionic currents and in levels of intracellular calcium.

Immunocytochemical detection of phosphatidylinositol 4,5-bisphosphate in Epon embedded specimens

A comparison between the time-consuming freeze-substitution Lowicryl HM 20 embedding procedure with the Epon embedding method for the immunocytochemical detection of phosphatidylinositol 4,5-bisphosphate (PIP2) by means of a monoclonal antibody is described. The results indicate that the intracellular localization of the phospholipid and the efficiency of its identification are similar, opening the possibility of performing the immunoreaction also on samples that are routinely processed for pathological investigations.

Immunocytochemical detection of the intranuclear variations of phosphatidylinositol 4,5-bisphosphate amount associated with changes of activity and amount of phospholipase C beta 1 in cells exposed to mitogenic or differentiating agonists

The intracellular localizations of phosphatidylinositol 4,5-bisphosphate (PIP2) and of its hydrolyzing enzyme phospholipase C (PLC; in this case the beta 1 isoform) have been evaluated by electron microscope immunocytochemistry in cells exposed to mitogenic or differentiating agents. These cells have been previously demonstrated to present a signal transduction system based on the polyphosphoinositide hydrolysis localized at the nuclear level, which can be specifically modulated by agonists. The results demonstrate that in Swiss 3T3 mouse fibroblasts mitogenically stimulated by insulin-like growth factor I (IGF-I), a rapid and transient decrease of the PIP2 detectable by immunogold labeling occurs at the nuclear interior. This effect appears due to the activation of the PLC beta 1 isozyme already present in the nucleus, since no significant variations of the enzyme amount and distribution can be detected by immunolabeling. However, after 30 min of exposure to IGF-I, when the PLC beta 1 activity is returned to basal level, a slight but significant increase of the enzyme amount is detected both in the nucleus and in the cytoplasm. On the other hand, an increased accumulation of PIP2 in the nucleus, accompanied by a decrease of the intranuclear amount of PLC beta 1 isozyme, have been observed in mouse erythroleukemia Friend cells, induced to erythroid differentiation by dimethylsulfoxide (DMSO). These results indicate that quantitative immunocytochemistry represents an increment in the available methodologies to investigate the complex regulation of nuclear PI-signalling.

Characterization of the hyperpolarization-activated current, I(f), in ventricular myocytes isolated from hypertensive rats

1. Left ventricular myocytes isolated from the heart of young (2-month-old) and old (18- to 20-month-old) spontaneously hypertensive rats (SHRs) were studied in the whole-cell configuration. Since multicellular preparations from old SHRs show a diastolic depolarization phase, we performed experiments to test whether it was associated with the presence of a hyperpolarization-activated If-like current. 2. In control Tyrode solution, a time-dependent increasing inward current activated by hyperpolarization was recorded in myocytes from old SHRs showing a diastolic depolarization phase. A barium-insensitive, caesium-sensitive, time-dependent inward current was recorded in a minority (4 of 33) of cells from young SHRs (membrane capacitance, 160 +/- 7 pF) but in 93% (25 of 27, P < 0.01) of myocytes from old SHRs (membrane capacitance, 355 +/- 19 pF, P < 0.01). 3. The current was fully activated at -120 mV and voltage of half-maximal activation was -88.1 +/- 1.5 mV; it was blocked by extracellular CsCl (4 mM) in a voltage-dependent manner. Reducing [K+]o from 25 to 5.4 mM caused a shift of the reversal potential from -17.3 +/- 3.8 to -25.7 +/- 2.7 mV and a 60% decrease of current conductance. 4. These findings suggest that an If-like current is present in rat ventricular myocytes from old SHRs, where it might favour the occurrence of spontaneous action potentials.

Use of specific antibody and circulating antigen serum levels in the hydatid immunodiagnosis of asymptomatic population

Levels of specific antibodies (Ab) and circulating antigens (CAg) were tested by ELISA in sera from 115 surgically confirmed hydatid patients, 41 individuals exhibiting other parasitic and unrelated diseases and 69 healthy subjects. Addition of CAg data to Ab detection in this sera collection increased sensitivity from 85% (only Ab) to 89% (Ab + CAg). Combination of ultrasonography with Ab and CAg serology for diagnosis of asymptomatic population in endemic areas was analyzed. One field survey (163 persons) involved both blood extraction and ultrasonography to all the population. Three people exhibited cyst images and all of them were Ab positive, while 6 Ab and 1 CAg positive individuals exhibited no cyst image. Another survey (1620 persons) involved a selection of 85 subjects for serology according to ultrasound data and record of family hydatid history. Twelve per cent exhibited no hydatid image being serologically positive and 14% were serologically negative but exhibited cyst image. Ultrasonography and serology (Ab and CAg) should be used in combination to maximize the diagnostic yield in asymptomatic population.

Minoxidil (Mx) as a prophylaxis of doxorubicin--induced alopecia

BACKGROUND

Minoxidil (Mx) is known to induce hair growth in men with male-pattern baldness. Based on this potential, the effectiveness of Mx 2% topical solution was evaluated in cancer patients (pts) to prevent doxorubicin-induced alopecia.

PATIENTS AND METHODS

48 female pts with different types of solid tumors treated with doxorubicin-based chemotherapy in a dose range of 50-60 mg/m2/cycle were randomly assigned to receive Mx 2% topical solution or placebo.

RESULTS

88% and 92% of pts in both arms showed severe alopecia (p = ns). No adverse effects were observed.

CONCLUSION

In this study Mx 2% topical solution was non-toxic but was not effective in the prevention of chemotherapy-induced alopecia.

Ionic basis of action potential prolongation of hypertrophied cardiac myocytes isolated from hypertensive rats of different ages

OBJECTIVE

The aim was to determine the ionic basis of action potential lengthening associated with cardiac hypertrophy.

METHODS

Action potentials and ionic currents of left ventricular myocytes isolated from normal and hypertrophied hearts were recorded with patch pipettes. Since cardiac hypertrophy is a time dependent process, myocytes isolated from hearts of spontaneously hypertensive rats (SHR) of different ages (3 and 18 months old) were compared with those of age matched normotensive controls (Wistar Kyoto rats, WKY).

RESULTS

Membrane capacitance, an index of cell size, was significantly higher in SHR than WKY. The degree of action potential prolongation was independently correlated with hypertension and its duration, resulting in a statistically significant lengthening of action potential in 18 month old SHR compared to age matched WKY and to 3 month old SHR. ICa,L density was not significantly modified in hypertrophied myocytes compared to normal controls. Depolarising steps positive to -40 mV activated an outward current, which was composed of both transient (ItO) and maintained components (Ilate) and played a major role in controlling repolarisation in rat ventricular myocytes. Ito density was significantly reduced in SHR myocytes compared to age matched WKY and was also smaller in 18 month old compared to 3 month old SHR. Ilate was not statistically different in 3 and 18 month old SHR and WKY. Current-voltage relationships for IK1 were completely superimposable in all groups.

CONCLUSIONS

Prolongation of action potential in the hypertrophied heart of SHR is due to specific alterations in the repolarising potassium current Ito. The phenomenon is directly related to the duration of hypertension.

Electrophysiological basis for the enhanced cardiac arrhythmogenic effect of isoprenaline in aged spontaneously hypertensive rats

We used normotensive (WKY) and spontaneously hypertensive rats (SHR) of 2, 6 and 18 months of age to get insight into the mechanisms responsible for the increased incidence of ventricular arrhythmias in hypertensive heart disease. We studied: (1) isoprenaline-induced spontaneous activity in isolated papillary muscle; (2) action potential characteristics; (3) beta-adrenoceptor and A1-adenosine receptor number and affinity; and (4) intracellular cyclic AMP (cAMP) levels. The saturation binding assay was performed in enzymatically isolated ventricular myocytes using the hydrophilic antagonist 3H-CGP 12177 for beta-adrenoceptors and 3H-DPCPX for A1-adenosine receptors. cAMP was measured by a competitive binding assay in myocytes before and after exposure to isoprenaline. Intracellular action potential was recorded from papillary muscles by means of 3 M KCl-filled glass microelectrodes. The presence of isoprenaline-induced automaticity was assessed by interrupting the electrical stimulation periodically. In isolated papillary muscles, isoprenaline (10 nM) induced spontaneous activity more frequently in 18-month-old SHR (90.0%) than in 6-(25.0%, P < 0.05) and 2-month-old SHR (0%, P < 0.001). No age-related statistically significant differences in isoprenaline-induced automaticity were observed in WKY. The incidence of isoprenaline-induced automaticity was higher in 18-month-old SHR than in age-matched WKY (22.2%, P < 0.05). KD and Bmax for beta-adrenoceptors and A1-receptors were not significantly modified in different groups. cAMP levels before and after isoprenaline stimulation were significantly lower in 18-month-old SHR than in age-matched WKY. Action potential duration (APD) was markedly prolonged in both normotensive and hypertensive rats during aging. APD was significantly prolonged in 18-month-old SHR compared to the WKY. A "diastolic depolarization", caused by the presence of delayed after-depolarizations, became apparent in the oldest animals. The slope of the delayed after-depolarization was increased by isoprenaline (1-10 nM) in 18-month-old SHR and this effect was significantly greater than that observed in 18-month-old WKY (P < 0.05). In conclusion, beta-adrenergic responsiveness is enhanced in hypertensive rats during aging, resulting in a greater incidence of abnormal automaticity. This effect does not appear to be related to changes in beta-adrenoceptor or A1-receptor density or affinity; it is likely that the electrophysiological alterations may play a role in this phenomenon.

High performance latex reagent for hydatid serology using an Echinococcus granulosus lipoprotein antigen fraction purified from cyst fluid in one step

A lipoprotein fraction from fertile bovine hydatid cyst fluid (FBHCF) was isolated by affinity chromatography on acrylic-heparin. The heparin-binding lipoprotein fraction (HBLF) was proved to be free from host immunoglobulins and albumin. Immunoblotting with confirmed human hydatid sera showed that the major relevant diagnostic bands in FBHCF were also present in HBLF. HBLF or FBHCF were used to sensitize polystyrene latex particles. HBLF-latex showed both higher reactivity with positive hydatid human sera and higher batch-to-batch reproducibility than FBHCF-latex. Titration of sera from 119 surgically confirmed hydatid patients, 48 with other parasitic diseases, 6 with unrelated diseases and 37 healthy subjects was performed using HBLF-latex and conventional ELISA (using FBHCF). Sensitivity and specificity were 83 and 87% for ELISA and 87 and 88% for HBLF-latex. These results indicate that, while being simpler and faster to perform, the HBLF-latex has a similar diagnostic value to that of the conventional ELISA test.

[The prognostic role of the parameters of cellular kinetics in head and neck tumors treated solely by radiotherapy]

Cell cycle and cell population characteristics, as obtained for head and neck cancers by flow-cytometry analysis of a single tumor sample, after in vivo bromodeoxyuridine (Burd) infusion, were proposed for their prognostic value and for their potentials for radiotherapy planning (conventional vs accelerated) and monitoring. DNA ploidy, the S phase fraction labeling index (LI), and duration (Ts) as well as cell population potential doubling time (Tpot) were measured in 42 head and neck squamous cell carcinoma patients and analyzed along with histopathological and clinical data. Twenty-seven patients received standard radiotherapy (70 Gy/35 fractions/7 weeks) whereas 15 patients were treated with the concomitant boost technique (75 Gy/40 fr/6 weeks). The univariate analysis of 31 patients, for whom all the cell kinetic parameters were available, indicated that local control probability was strongly affected by lymph node status (p = 0.05) and by potential doubling time (p = 0.04). Patients having tumor Tpot < 5 days had markedly lower two-year local control rate (13%) than patients with Tpot > 5 days (68%). Furthermore, tumors with Tpot < or = 5 days exhibited a trend toward better local control after concomitant boost regimen compared with the patients treated with standard regimen (p = 0.06). These preliminary results point out that Tpot could play a role as additional prognostic factor influencing disease outcome in head and neck carcinomas treated by radiotherapy. In patients with fast growth-rate tumors (Tpot < or = 5 days) a more aggressive radiotherapy combination or chemo-radiotherapy should be suggested.

[Abdominal visceral lesions in patients with multiple trauma]

The paper describes a series of 385 cases of multiple injuries which were treated between 1987 and 1991 at the Emergency Unit of the Fatebenefratelli Hospital in Milan. Special attention was paid to abdominal trauma and visceral injuries in terms of both diagnosis and treatment.

Prolonged propionyl-L-carnitine pre-treatment of rabbit: biochemical, hemodynamic and electrophysiological effects on myocardium

Recently it has been reported that prolonged treatment with propionyl-L-carnitine, a carnitine derivative, results in a positive inotropic effect. To gain further insight into its mode of action, we pre-treated 253 rabbits for up to 10 days with daily doses of 1 mmol/kg propionyl-L-carnitine or L-carnitine intraperitoneally, using saline-treated animals as control. Twenty-four hours after the last injection, we isolated papillary muscles for electrophysiological investigations. Whole hearts were used in perfusion experiments for biochemical and hemodynamic measurements. In addition, mitochondria were harvested from these hearts for the analysis of their function. Plasma and cardiac levels of free carnitine, along with plasma short-chain acylcarnitines, increased at least two-fold after treatment with carnitine or its propionyl-ester, with concomitant rises in tissue long-chain acylcarnitine and long-chain acyl-CoA. At the time of animal sacrifice, treatment did not increase plasma or tissue propionyl-L-carnitine content. The studies carried out with perfused hearts and isolated mitochondria failed to show an effect of propionyl-L-carnitine pre-treatment on high-energy phosphate metabolism or respiration. Papillary muscles from animals, treated for 10 days, showed a lengthening of the action potential duration from 63 +/- 4 to 102 +/- 6 ms (P less than 0.001) at -10 mV. Perfused hearts from these rabbits displayed positive inotropy, as indicated by an improved pressure development at higher ventricular filling volumes, e.g., from 39 +/- 4 to 60 +/- 3 mmHg (P less than 0.05) at 3.6 ml. Pre-treatment with L-carnitine or saline failed to affect the electrophysiological and hemodynamic variables. Thus, prolonged treatment of rabbits with propionyl-L-carnitine, but not with L-carnitine, improved contractility and lengthened action potential duration in isolated muscle preparations.