An experimental animal model of intestinal obstruction to simulate in utero therapy for jejunoileal atresia

OBJECTIVE

To obtain 'intestinal atresia-like' conditions in the fetal lamb model to subsequently allow in utero surgical repair.

METHODS

Six time-dated pregnant sheep underwent general anesthesia at 75 days of gestation (term 145 +/- 5 days). After maternal laparotomy and hysterotomy, the fetal abdomen was opened. Once the jejunoileal intestinal loop was identified, the mesenteric vessels were isolated, ligated, and sectioned in 2 fetuses, and in the remaining 5 fetuses the bowel loop was ligated. Two further fetuses were used as controls and underwent sole laparotomy. Of the group of 7 fetuses 2 were reoperated at 100-105 days of gestational age and underwent intestinal recanalization. Eight fetuses were delivered at term by cesarean section and the remaining 1 by spontaneous delivery. One newborn underwent neonatal entero-enteric anastomosis.

RESULTS

4 out of 6 fetuses survived, in utero intestinal or vascular ligation having provoked an 'intestinal atresia-like' picture. The animal operated at birth died. The 2 control fetuses and the 2 fetuses with in utero intestinal recanalization survived until term.

CONCLUSION

The present study shows that in utero treatment of intestinal obstruction is possible in an experimental model.

Hyperplasia of the aorticopulmonary paraganglia: a new insight into the pathogenesis of sudden infant death syndrome?

In this study, the Authors search for morphologic alterations in the aorticopulmonary paraganglia (APP) of sudden infant death syndrome (SIDS) victims when compared with age-matched controls. Morphometric studies on serial sections of the APP were performed with an image analyzer in combination with a standard microscope attached to a video camera. APP hyperplasia, characterized by an increase in some parameters such as number, mean lobule diameter and total glomic tissue volume when compared with age-matched controls, was observed in 23.8% of SIDS victims. Similar alterations have been reported in peripheral chemoreceptors of animals and human beings who are chronically hypoxemic. In SIDS, it could reflect an abnormal chemoreceptor function, contributing to an altered respiration control.

The Italian version of the Family Assessment Device

The aim of the study was to evaluate in a heterogeneous. Italian sample (n = 340) the psychometric properties of the Italian version of the Family Assessment Device (FAD), a 60-item questionnaire assessing family functioning. The questionnaire was administered to psychiatric (n = 116), medical (n = 114) and non-clinical samples (n = 110). In a sample of 30 non-clinical subjects the temporal stability of the FAD was investigated. The results showed a good temporal stability for Problem Solving, General Functioning. Communication, and Affective Responsiveness scales, and a good internal reliability of the scale. Factor analysis of the Italian version provided discrepancies with the hypothesized structure of the instrument, leading to the identification of seven slightly different dimensions. The proposed seven-factor model of the instrument did not provide a good fit to our data. The results of our study suggest the need for a major improvement in the adaptation of the FAD in the Italian setting.

Analysis of lung damage induced by trichloroethylene inhalation in mice fed diets with low, normal, and high copper content

Copper is both an essential nutrient required for the activity of several enzymes and a toxic element able to catalyze free radical formation. Trichloroethylene (TCE) is a xenobiotic that generates epoxidic intermediates by bioactivation through the cytochrome P-450 system. In this study, the influence of a dietary copper imbalance on the TCE-induced lung damage was investigated. Weaning mice were fed copper-deficient, copper-sufficient, and copper-excessive diets. After 4 wk, mice were exposed for 30 min to 6,500 ppm of TCE and euthanatized 48 hr later. Lung damage in the TCE-treated mice consisted of vacuolations of Clara cells and was quantitatively evaluated by counting the vacuolated cells per micrometer of basal lamina. At the ultrastructural level, vacuolations appeared as the result of hydropic swelling of the endoplasmic reticulum cisternae. The copper-deficient mice presented the highest number of vacuolated Clara cells. These mice also showed alteration of the capillary endothelium and interstitium and decreased pulmonary copper-zinc-superoxide dismutase activity. Occurrence of oxidative stress in lungs of both copper-sufficient and copper-deficient mice following TCE treatment was indicated by a decrease in reduced glutathione and an increase in its oxidized form.

Intrauterine growth retardation: evidence for the activation of the insulin-like growth factor (IGF)-related growth-promoting machinery and the presence of a cation-independent IGF binding protein-3 proteolytic activity by two months of life

Thirty-seven children with intrauterine growth retardation (IUGR) were enrolled in a 3-mo longitudinal study. Weight, length, and knee-heel length (by knemometry) were measured at birth and at 7, 14, 30, 60, and 90 d. GH, IGF-I, IGF binding protein (BP)-3, IGFBP-1, and C-peptide were measured at birth and at 2 mo. IGFBP-3 Western immunoblotting and proteolytic activity assay were also performed. Twenty-five newborns with birth weight appropriate for gestational age were chosen as controls. At birth IUGR newborns showed levels of GH and IGFBP-1 significantly higher, and IGF-I, IGFBP-3, and C-peptide significantly lower than control subjects. At 2 mo GH and IGFBP-1 levels decreased, whereas IGF-I, IGFBP-3, and C-peptide rose, attaining the concentrations found in control subjects at birth. Baseline peptide levels as well as their 2-mo variations did not correlate with the gain in weight, supine length, and knee-heel length recorded at 3 mo. Fourteen of nineteen IUGR cord blood samples showed the presence of the intact approximately 42-39-kD IGFBP-3 doublet and the major approximately 29-kD fragment. At 2 mo the IGFBP-3 band pattern was characterized by the predominance of a approximately 18-kD fragment in 6 of 19 tested IUGR infants. The incubation of 2-mo IUGR samples with normal adult serum induced the appearance of the approximately 18-kD band, which was not modified by the addition of EDTA. These results suggest that: 1) the IGF-related growth-promoting mechanism is impaired in IUGR children at birth but is fully restored at 2 mo; 2) the cord blood levels of GH, IGF-I, IGFBP-3, IGFBP-1, and C-peptide are not predictive of the weight and length gain during the first 3 mo of life; 3) IUGR children have at least two different IGFBP-3 proteases, one cation-dependent protease that is present at birth and able to yield the major approximately 29-kD IGFBP-3 fragment and a second one, with a different activation timing, which exhibits cation independence and induces the formation of a approximately 18-kD IGFBP-3 form.

Decrease of cytochrome c oxidase protein in heart mitochondria of copper-deficient rats

Copper deficiency has been reported to be associated with decreased cytochrome c oxidase activity, which in turn may be responsible for the observed mitochondrial impairment and cardiac failure. We isolated mitochondria from hearts of copper-deficient rats: cytochrome c oxidase activity was found to be lower than in copper-adequate mitochondria. The residual activity paralleled copper content of mitochondria and also corresponded with the heme amount associated with cytochrome aa3. In fact, lower absorption in the alpha-band region of cytochrome aa3 was found for copper-deficient rat heart mitochondria. Gel electrophoresis of protein extracted from mitochondrial membranes allowed measurements of protein content of the complexes of oxidative phosphorylation, revealing a lower content of complex IV protein in copper-deficient rat heart mitochondria. The alterations caused by copper deficiency appear to be specific for cytochrome c oxidase. Changes were not observed for F0F1ATP synthase activity, for heme contents of cytochrome c and b, and for protein contents of complexes I, III and V. The present study demonstrates that the alteration of cytochrome c oxidase activity observed in copper deficiency is due to a diminished content of assembled protein and that shortness of copper impairs heme insertion into cytochrome c oxidase.

Use of an algorithm for administering subcutaneous heparin in the treatment of deep venous thrombosis

BACKGROUND

Despite the widespread use of subcutaneous heparin in the initial treatment of deep venous thrombosis, there are no guidelines for achieving adequate anticoagulation with this drug.

OBJECTIVE

To implement a weight-based algorithm for the administration of subcutaneous unfractionated heparin after an intravenous loading dose.

DESIGN

Prospective cohort study.

SETTING

University hospital.

PARTICIPANTS

70 outpatients with proximal venous thrombosis.

INTERVENTION

An intravenous bolus of heparin followed by a subcutaneous injection of heparin in doses adjusted for body weight. Subsequent adjustments of the subcutaneous heparin dose were scheduled twice daily according to the algorithm; the activated partial thromboplastin time (aPTT) was measured in the mid-interval (target range, 50 to 90 seconds).

RESULTS

The therapeutic threshold aPTT (> or = 50 seconds) was achieved in 61 patients (87%) within 24 hours and in 69 patients (99%) within 48 hours. In 7 patients (10%), a supratherapeutic aPTT lasted more than 12 hours. No major bleeding episodes or cases of heparin-induced thrombocytopenia were seen. Three patients (4.3% [95% CI, 0.9% to 12.0%]) had recurrent thromboembolism during 3 months of follow-up.

CONCLUSION

The administration of subcutaneous heparin according to a weight-based algorithm allows the rapid achievement of effective and safe anticoagulation in patients with deep venous thrombosis.

Interaction of the DNA modifying proteins VirD1 and VirD2 of Agrobacterium tumefaciens: analysis by subcellular localization in mammalian cells

Interaction between Agrobacterium tumefaciens and plants provides a unique example of interkingdom gene transfer. Agrobacterium, a plant pathogen, is capable to stably transform the plant cell with a segment of its own DNA called T-DNA (transferred DNA). This process depends, among others, on the specialized bacterial virulence proteins VirD1 and VirD2 that excise the T-DNA from its adjacent sequences. Subsequent to transfer to the plant cell, the virulence protein VirD2, through its nuclear localization signal (NLS), is believed to guide the T-DNA to the nucleus. The T-DNA then is integrated into the plant genome. Although both of these proteins are essential for bacterial virulence, physical interaction of them has not been analyzed so far. We studied associations between these proteins by expressing them in mammalian cells and by testing for intracellular localization and colocalization. When expressed in human cells [HeLa, human embryo kidney (HEK) 293], the VirD2 protein homogeneously distributed over the nucleoplasm. The presence of any of two NLSs, on the N and C termini of VirD2, was sufficient for its efficient nuclear localization whereas deletion of both NLSs rendered the protein cytoplasmic. However, this double NLS mutant was translocated to the nucleus in the presence of wild-type VirD2 protein, implying VirD2-VirD2 interaction. The VirD1 protein, by itself localized in the cytoplasm, moved to the nucleus when coexpressed with the VirD2 protein, suggesting VirD1-VirD2 interaction. This interaction was confirmed by coimmunoprecipitation tests. Of interest, both proteins coimported to the nucleus showed a similar, peculiar sublocalization. The data are discussed in terms of functions of the VirD proteins. In addition, coimport of proteins into nuclei is suggested as a useful system in studying individual protein-protein interactions.

Erythrocyte engineering for drug delivery and targeting

A new procedure for the encapsulation of non-diffusible drugs into human erythrocytes was developed. With as little as 50 ml of blood and by using a new apparatus, it was possible to encapsulate a variety of biologically active compounds into erythrocytes in 2 h at room temperature and under blood-banking conditions. The process, which is based on two sequential hypotonic dilutions of washed red cells followed by concentration with a haemofilter and resealing of red cells, allows a 35-50% cell recovery and approx. 30% encapsulation of added drugs. The resulting processed erythrocytes have a normal survival in vivo and can be modified further, with the same apparatus, to increase their recognition by tissue macrophages to perform as a drug-targeting system. The new equipment designed and built for this procedure was named 'Red Cell Loader'.

Hypoglycemia, hypoxia, and ischemia in a corticostriatal slice preparation: electrophysiologic changes and ascorbyl radical formation

Experimental and clinical data suggest that oxygen and/or glucose deprivation alters electrical transmission in the brain and generates free radicals, which may mediate neuronal death. We have analyzed the effects of oxygen and/or glucose deprivation on both excitatory transmission, by measuring field potential amplitude, and free radical production, by using electron spin resonance (ESR) spectroscopy, in a corticostriatal slice preparation. Combined oxygen and/or glucose deprivation (ischemia) lasting 10 to 20 minutes induced a long-term depression of field potential amplitude. The ascorbyl radical could only be detected in brain slices during the reperfusion-phase after 30 minutes of ischemia. It appeared in the early minutes after the washout of ischemic medium and remained stable throughout the reperfusion phase. This radical was never detected in the external medium. Ischemia induced only a slight, but progressive, release of lactate dehydrogenase (LDH) into the external medium during the reperfusion phase. In contrast, exposure of slices to hypoxia or hypoglycemia alone resulted in transient depression of field potential amplitude, and no generation of ascorbyl radicals was observed on reperfusion. We propose that the long-lasting loss of electrical signals is the early sign of neuronal damage during ischemia. On the other hand, ascorbyl radical formation may be considered an indicator of neuronal injury after prolonged energy deprivation.

[Sudden cardiac death in acromegaly. Anatomopathological observation of a case]

Involvement of the cardiovascular system in patients affected by acromegaly is an important factor in morbidity and mortality. The diagnosis in these subjects is acromegalic cardiomyopathy with cardiac decompensation, arrhythmias and sudden death. The pathologic substrate has rarely been described. The present study reports the findings in a case of sudden death in a 54-year-old man, affected by acromegaly. Subsequent diagnostic investigation revealed the characteristic aspects of acromegalic cardiomyopathy in the common myocardium and the presence of hyperacute myocardial infarct of the antero-septal wall of the left ventricle. Examination of conduction tissue revealed slight fibrolipomatosis and dispersion of the atrio-ventricular node (AVN), which extended to the His bundle and bifurcation. The right branch was prematurely intramural with sclerosis and lipomatosis. This location in atrio-ventricular conduction system has seldom been reported in the literature and if so, with different lesions from those found in the case we investigated. The results of microscopic examination convalidate the hypothesis of electrical instability in the heart, as confirmed by the subject's history of ventricular extrasystoles, left branch block and attacks of angina after effort. Death was correlated to hyperacute myocardial infarction of the anteroseptal wall of the left ventricle, in a subject with history of angina, affected by acromegalic cardiomegaly and electric instability. In this case, sudden death could also be considered arrhythmogenic in relation to the additional workload by persistent hormonal stimulation.

Screening of gestational diabetes in Tuscany: results in 2000 cases

According to the guidelines of the "Third international workshop conference on GDM", we have examined 2000 pregnant women. The glucose challenge test (GCT) was positive in 408 cases (20.4%) and negative in 1592 (79.6%). The OGTT (Carpenter and Coustan's criteria) was performed in 647 pregnant women. GDM and IGGT prevalence was of 6.25% and 5.5% respectively and normal glucose tolerance (NGT) 88.25%. The GCT effectiveness for GDM and IGGT diagnosis is: sensibility 75.1%, specificity 44%, positive predictive value 46.4% and negative predictive value 74%. GDM and IGGT compared with NGT women were significantly older (p < 0.05) and prepregnancy BMI was higher (p < 0.01); the prevalence of previous macrosomia (p < 0.01), previous gestational diabetes (p < 0.01) and family history for diabetes mellitus (p < 0.05) was greater in GDM and IGCT. The prevalence of preterm delivery was higher in both GDM and IGCT (GDM 12.5% and IGGT 15.4% vs NGT 6%; p < 0.01), as well as the prevalence of cesarean sections (GDM 31.6% vs IGGT 23.5% and NGT 20.3%; p < 0.02), and the occurrence of macrosomia (GDM 27.6%, IGGT 16.6% and NGT 16.2%). In addition a higher prevalence (p < 0.01) of hyperbilirubinaemia, hypoglycemia and hypertrophy cardiomyopathy was observed in newborns from GDM women. Our data show that: GCT has a good specificity for GDM diagnosis, prevalence of GDM in our population is about 6%, GDM is still correlated to an elevated maternal and neonatal morbility.

IGF-I and IGF-binding protein-1 are related to cortisol in human cord blood

OBJECTIVE

To assess cortisol concentrations in cord blood and investigate their relationships with the IGF system.

STUDY DESIGN

Fifteen newborns with birth weight appropriate for gestational age (AGA) and 30 children with intrauterine growth retardation (IUGR) were studied. Serum samples were collected from umbilical cord blood and cortisol, IGF-I and IGF-binding proteins (IGFBPs)-1 and -3 were measured. IUGR infants were followed up for 3 months with repeated measurements of weight, supine length and knee-heel length (by knemometry).

RESULTS

IUGR newborns showed significantly greater concentrations of IGFBP-1 (P<0.0001) and lower concentrations of IGF-I (P< 0.0001) and IGFBP-3 (P< 0.0001) than did controls. In AGA children, cortisol correlated inversely with IGF-I (r=-0.75, P< 0.002) and directly with IGFBP-1 (r=0.52, P <0.05), whereas no correlation between cortisol and IGF system-related variables was observed in IUGR. Finally, in IUGR children an inverse correlation was found between length gain in the first trimester of life and cortisol concentrations at birth (r=-0.54, P < 0.005).

CONCLUSIONS

Cortisol might be a physiological regulator of fetal growth, at least in the last part of pregnancy, by modulating IGF-I and IGFBP-1 release under conditions of fetal stress. In IUGR children, a rearrangement of this growth control mechanism seems to occur. The close inverse relationship of cortisol with linear growth, if confirmed by large-scale studies, suggests cord blood cortisol to be potentially predictive of early postnatal catch-up growth in IUGR infants.

Macrophage protection against human immunodeficiency virus or herpes simplex virus by red blood cell-mediated delivery of a heterodinucleotide of azidothymidine and acyclovir

Human herpesvirus (HSVs) are distributed worldwide and are among the most frequent causes of viral infection in HIV-1-immunocompromised patients. Hence, therapeutic strategies able to inhibit HSV-1 and HIV-1 replication are sorely needed. Until now, the most common therapies against HSV-1 and HIV-1 infectivity have been based on the administration of nucleoside analogs; however, to be active, these antiviral drugs must be converted to their triphosphorylated derivatives by viral and/or cellular kinases. At the cellular level, the main problems involved in the use of such drugs are their limited phosphorylation in some cells (e.g., antiretroviral drugs in macrophages) and the cytotoxic side effects of nucleoside analog triphosphates. To overcome these limitations, a new heterodinucleotide (AZTp2ACV) consisting of both an antiretroviral and an antiherpetic drug, bound by a pyrophosphate bridge, was designed and synthesized. The impermeant AZTp2ACV was encapsulated into autologous erythrocytes modified to increase their recognition and phagocytosis by human macrophages. Once inside macrophages, metabolic activation of the drug occurred. The addition of AZTp2ACV-loaded erythrocytes to human macrophages provided effective and almost complete in vitro protection from HIV-1 and HSV-1 replications, respectively. Therefore, AZTp2ACV acts as an efficient antiviral prodrug following selective targeting to macrophages by means of loaded erythrocytes.

In vivo evidence of apoptosis in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary heart muscle disease characterized by progressive atrophy of the right ventricular myocardium with fibro-fatty replacement and the risk of electrical instability and sudden death. The disease is often familial and the aetiopathogenesis is still unknown. Recently apoptosis (genetically determined cell death) was postulated to account for progressive loss of myocardium. To establish whether apoptosis is present in ARVC, right ventricular endomyocardial biopsies from 20 patients with clinical and histological diagnosis of ARVC were examined by electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling method (TUNEL). Apoptotic index was calculated as the percentage of positive nuclei in sections stained by TUNEL. Cell proliferation activity was also assessed by argyrophilic staining of the nucleolar organizer region (AgNOR) and MIB-1 antibody analysis. Twenty biopsies taken from patients during monitoring of cardiac transplantation (grade 0 rejection) served as control. Occurrence of apoptosis was correlated with clinical history duration and the presence of acute symptoms and signs like angina, pyrexia, erythrocyte sedimentation rate and creatine phosphokinase elevation, as well as ST segment elevation on basal electrocardiogram. Electron microscopy and TUNEL revealed presence of apoptotic myocytes in seven cases (35%) with a mean apoptotic index of 24.4+/-9.8. The remaining 13 patients and all of the 20 controls were negative both at the electron microscopy and TUNEL. Presence of apoptosis appeared to be significantly related to clinical history duration of less than 6 months (P < 0.001) and presence of acute symptoms and signs (P = 0.007). AgNOR staining and MIB-1 antibody analysis ruled out cell proliferation activity. In conclusion, apoptosis is present in endomyocardial biopsies of patients with ARVC, especially in the early symptomatic phase of disease. Myocardial destruction with replacement by fat may be episodic rather than gradual and continuous.

Use of nonvolatile buffers in liquid chromatography/mass spectrometry: advantages of capillary-scale particle beam interfacing

The use of nonvolatile buffers like phosphate and citrate is usually incompatible with mass spectrometric detection or may heavily interfere with ion generation. In the case of conventional HPLC flow rates, the continuous buffer deposition produces fouling of the mass spectrometer ion source and may worsen the performance of any LC/MS interface as well. Our research group demonstrated that reducing the mobile phase flow rate in a particle beam interface improves the nebulization and enhances the overall performance. We have also assumed that such a modification may better handle potentially instrument harmful solvents or nonvolatile HPLC buffers. Since the presence of salts does not interfere with the electron ionization process, the particle beam interface can be considered, in principle, particularly suitable for those chromatographic separations that benefit from nonvolatile buffers. The microscale flow rate interface, developed in our laboratory, generates an aerosol from 1 microL/min of mobile phase flow rate. Under these conditions, the absolute amount of a nonvolatile buffer actually introduced into the system is approximately 1/1000 of that carried by a conventional HPLC column, slowing its deposition. This assumption was verified with a real-world application requiring the use of a phosphate buffer at a maximum concentration of 10 mM. It involved the determination of dexamethasone, an anti-inflammatory drug, in human blood after its administration to a patient. Several crucial mass spectral and chromatographic parameters were monitored during a 35-day period of intense use. Neither appreciable signal modification nor evident buffer deposition was observed during the test period, with only a normal and limited run-by-run and day-by-day variation of the instrument response.

[Evaluation by bioelectric impedance of body fluid compartments and body mass in cardiosurgical patients before and after total cardiopulmonary bypass]

BACKGROUND

To evaluate the influence of extracorporeal circulation (ECC) on fluid compartments and body mass using impedance measurements.

METHODS

A prospective study was performed in 20 consecutive patients undergoing ECC during heart surgery at the Department of Heart Surgery of Verona Hospital. Resistance or reactance measurements at 1-5-10-50-100 KHz were performed in 20 patients undergoing heart surgery for valvular or coronary pathologies in class NYHA I or II, preoperatively and on day 1, 3 and 6 in order to evaluate total body water (TBW), intracellular water (ICW), extracellular water (ECW), thin and fat body mass. Weight, fluid-electrolytic balance and hematochemical parameters relating to electrochemical phenomena and the distribution of volumes in the various compartments, namely sodium, potassium and plasmatic osmolarity, were measured at the same times. Comparisons were made both between the data and during ECC.

RESULTS

It was found that there was a mean postoperative weight gain of 2 kg in terms of total body water. Subsequently, this finding tended to decrease to basal values by day 6. Immediately after ECC, the water gain appeared to be predominantly extracellular, whereas the intracellular increase peaked on day 1. The change in total body water was correlated with the weight and fluid balance, but electrical measurements showed values above the corresponding weight gain. The duration of ECC was significantly correlated with bioelectric parameters, but not with absolute weight values.

CONCLUSIONS

The method proved useful for the purpose, especially with regard to the overall population examined rather than individual patients. The dual-compartment electric model appears to be more suitable than the single-compartment model for exploring the different compartments. The trend of weight and total body water, which were correlated in pattern but not in absolute values, may be interpreted as a redistribution of fluids, also suggested by changes in electric parameters relating to compartmental distribution.

A survey of the gastro-intestinal nematodes of roe deer (Capreolus capreolus) in a mountain habitat

Two hundred and twenty one roe deer from a xeric inner-alpine valley in Italy were investigated along four yearly cycles for the presence of gastro-intestinal nematodes. Road kills were the main source of this material. Spiculopteragia spiculoptera and Ostertagia leptospicularis, with their "minor" morphs S. mathevossiani and O. kolchida, were the dominant abomasal species, whereas Nematodirus europaeus was the only dominant species in the small intestine; therefore, species composition was typical of this ruminant host. Nematodes whose prime hosts are domestic and wild Bovids (Rupicapra rupicapra) were found occasionally. Abundances were low (407 nematodes in the abomasum, 209 in the small intestine, 6 in the large intestine) in spite of a high population density. Significant differences in worm counts were observed between seasons (abomasal worm counts peaked in late spring and summer whereas N. europaeus was more abundant in winter), years and between sex and age classes (higher abomasal counts in bucks vs does and in adult individuals vs fawns). Associations between worm counts and the condition of roe deer (five parameters taken into account) could not be demonstrated unambiguously. Based on data, the use of abomasal counts as a herd health index in the study area is not recommended.

Nuclear association of cyclin D1 in human fibroblasts: tight binding to nuclear structures and modulation by protein kinase inhibitors

The association of cyclin D1 with nuclear structures was investigated in normal human fibroblasts by using hypotonic detergent extraction procedures, immunofluorescence quantitation with flow cytometry, and Western blot analysis. About 20% of the total cellular levels of cyclin D1 was found to be tightly bound to nuclear structures, being the complex formation resistant to DNase I treatment and to high salt extraction. Maximal levels of the insoluble form of the protein were found in the middle to late G1 phase of the cell cycle. Cell fractionation and immunoprecipitation techniques after in vivo 32P-labeling showed that both soluble and nuclear-bound forms of cyclin D1 were phosphorylated. Both fractions were reactive to an anti-phosphotyrosine antibody, while only the latter was detectable with an anti-phosphoserine antibody. Treatment with the protein kinase inhibitor staurosporine, which induces a cell cycle arrest in early G1 phase, strongly reduced cyclin D1 phosphorylation. Concomitantly, the ratio of nuclear-bound/total cyclin D1 levels was reduced by about 60%, compared with the control value. The protein kinase A specific inhibitor isoquinoline-sulfonamide (H-89) induced a similar reduction in the ratio, with no significant modification in the total amount of protein. In contrast, both calphostin C and bisindolylmaleimide, specific inhibitors of protein kinase C, consistently increased by 30-50% the ratio of nuclear-bound/total amount of the cyclin protein. These results suggest that, during the G1 phase, formation of an insoluble complex of cyclin D1 occurs at nuclear matrix structures and that this association is mediated by a protein kinase A-dependent pathway.

Poly(ADP-ribose) synthesis: a useful parameter for identifying apoptotic cells

Cell death by apoptosis was analysed in HeLa cells either treated with the antitumoral drug bleomycin or depleted of growth factors by long-term culture without medium change. The interference of apoptosis with normal cell cycle progression was followed by flow cytometry in cells stained with propidium iodide and with antibody to S-phase-related PCNA protein. Bleomycin-treated cells showed a net accumulation in G2/M phase paralleled by the appearance of material with a subdiploid DNA content. Cells with a subdiploid DNA content were also present in growth factor-depleted cultures and were shown to derive from all the cell cycle phases. To identify apoptotic features in HeLa cell cultures, we applied a recently developed assay based on the simultaneous analysis in the single cell of three parameters, namely chromatin condensation, DNA degradation and poly(ADP-ribose) synthesis. Apoptotic cells were visualized by sequential reactions: Hoechst staining, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling assay and immunoreaction with anti-poly(ADP-ribose) monoclonal antibody. Positive reactions were obtained for cells at different stages of the apoptotic programme showing condensed nuclei, fragmented chromatin and apoptotic bodies.

Sudden death in young people with apparently isolated mitral valve prolapse

Ventricular electrical instability and sudden death in mitral valve prolapse (MVP) have been related to mitral valve regurgitation and left ventricular dysfunction, autonomic nervous system abnormalities, or underlying cardiomyopathy. The aim of the present study was to assess the frequency, nature and pathophysiologic significance of histologic myocardial abnormalities in young patients with apparently isolated MVP and sudden cardiac death. Among 163 cases of sudden cardiovascular death in young people, MVP was the only cardiac pathology found at postmortem gross examination in 17 (10%) (12 females and 5 males) aged 14 to 35 years, mean 24. In 12 cases sudden death occurred at rest (during pregnancy in 2). MVP was diagnosed during life in 8 patients, 6 of whom had experienced palpitations and/or syncope, and 3 had premature ventricular beats. In every case, postmortem gross examination revealed "floppy" mitral valve leaflets with marked myxoid degeneration, and no other cardiovascular pathology. Cardiomegaly with left chamber enlargement was observed in 5 cases (mild in 3 and moderate in 2). In 12 cases (70%), histopathologic study disclosed myocardial abnormalities which consisted of focal myocardial atrophy and fatty replacement of the right ventricular wall (mostly the outflow tract) in 9 cases, left ventricular myocardial disarray (without hypertrophy) in 2, and lymphocytic infiltrates in one. "Foetal" dispersion of specialized atrioventricular junction and fasciculoventricular Mahaim's fibers were found in 2 cases. In conclusion, apparently isolated MVP was found in nearly 10% of sudden cardiovascular fatalities in young people. Most young sudden death victims with MVP were asymptomatic females without significant mitral valve regurgitation. In more than two-thirds of the cases, histopathologic examination evidenced underlying silent but potentially arrhythmogenic myocardial substrates, mostly consisting of segmental right ventricular cardiomyopathic changes.

[Sudden cardiac death in non-professional athletes]

Sudden death during sports activities in non-professional athletes is a rare occurrence, however it is of great interest in clinical pathology and forensic medicine. We performed chemico-toxicologic and histopathologic investigations in three cases of sudden cardiac death in non-professional athletes, focusing in particular on the cardiac conduction system. Examination of conduction tissue was performed on sections seriated every 150 microns, stained alternately with hematoxylin-eosin and Heidenhain's trichrome (azan). In all three cases diagnostic evidence showed hyperacute myocardial infarction, due to spasm of coronaries with mild atherosclerosis, and myocardial lesions due to reperfusive necrosis. The pathogenesis of sudden death in young athletes is not related only to ischemic-coronary damage that is not exclusively mechanical, but also a dynamic event (spasm and reperfusion), but also to fatal arrhythmias related to abnormal findings in the conduction system. Such findings can therefore be considered the morphologic substrate of sudden cardiac death.

Purification of a fully metal-depleted Cu, Zn superoxide dismutase from copper-deficient rat liver

A copper-deprived form of the enzyme Cu, Zn superoxide dismutase was identified in the liver of rats made copper-deficient by dietary restriction. In homogenates of such livers Cu, Zn superoxide dismutase presents a dis-homogeneous electrophoretic profile with respect to the native enzyme. When rat liver extracts were treated with exogenous copper an electrophoretic pattern resembling the native one was observed. Enzyme purified by chromatography on DE-52 resin shows two major components, one corresponding to genuine, native enzyme and another one, eluting at higher ionic strength. The latter protein (Fraction II) consists of several isoforms which show the same characteristics of the native superoxide dismutase as far as immunoreactivity and molecular weight are concerned, but with decreased contents of copper and zinc. Its catalytic constant, referring to copper content, was 15 times lower than that obtained for the native enzyme. Moreover, the catalytic power of purified Fraction II was not regained upon incubation with copper. The occurrence of a superoxide dismutase void of metals confirms the hypothesis that this protein plays a dual physiological role: in metal metabolism and in superoxide anion dismutation.