Nitric oxide production is increased in the spermatic veins of adolescents with left idiophatic varicocele

BACKGROUND/PURPOSE

The existence of an excessive release of nitric oxide (NO) within dilated spermatic veins has been recorded in adults with varicocele suggesting a high oxidative stress. The authors investigated whether NO overproduction is already present in the dilated veins of adolescent varicocele and which enzymatic isoforms in the spermatic vein could be expressed.

METHODS

The study group consisted of 10 adolescent patients affected by left idiophatic varicocele of grade II and III. The increase in NO production was established by determination of serum concentration of L-hydroxyarginine (L-NHA) and Nitrite/nitrate (NOx). Both endothelial and inducible NOsynthase (NOS) were investigated by Western blot analysis and by immunohistochemical localization using specific monoclonal fluorescein conjugated antibodies.

RESULTS

Serum L-NHA levels were significantly greater in the spermatic veins when compared with the peripheral veins 176.8 +/- 32.3 micromol/L versus 3.38 +/- 0.64 micromol/L (P =.0004 Similarly, NOx levels were increased, respectively, 68.2 +/- 16.7 nmol/mL versus 12.9 +/- 2.65 nmol/mL (P =.029). Endothelial NOS was localized in the spermatic vein of varicocele patients, but not overexpressed; the inducible isoform was not detected.

CONCLUSIONS

Adolescents with varicocele already present an increase in NO within dilated veins. The dilated spermatic vein is not the major source for the increase in NO level. These results could have an implication in the natural history of adolescent varicocele and in programming the ideal time for surgical treatment.

New insights in the pathophysiology of mitral and aortic regurgitation in pediatric age: role of angiotensin-converting enzyme inhibitor therapy

This review has been focused on the new insights in the pathophysiology of mitral and aortic regurgitation and on the role of ACE-inhibitor therapy in children with chronic volume overload due to left-sided valvular lesions. Recent clinical studies show that these drugs have favorable effects when administered orally in chronic mitral and aortic regurgitation. Interestingly, the beneficial effects of ACE-inhibition regard the basic anatomic, hemodynamic and adaptive pathologic conditions related to volume overload, namely, the regurgitant orifice area and volume and ventricular remodeling. The heart is a plastic structure, constantly being altered in size, shape and composition in response to chronic volume overload. Thus, modulation of cardiac plasticity by ACE-inhibition raises the possibility of using new therapeutic strategies specifically designed to prevent and/or antagonize the mechanical disadvantages secondary to volume overload-induced cardiac remodeling. The beneficial effects of ACE-inhibition have also been observed in growing children with asymptomatic valvular regurgitation; thus, it appears that the unloading therapy has the potential of influencing the natural history of both mitral and aortic regurgitation and possibly delays surgical valve repair or replacement. These data justify early inhibition of the renin-angiotensin system in children with left ventricular volume overload due to mitral and aortic regurgitation.

Molecules that inhibit T-cell functions: cytochemical localization and shuttling

Adaptive immune responses to antigens are mediated by specific receptors expressed on B cells (BCR's) and T cells (TCR's). Effector cells and memory cells are produced following a proliferative wave that accounts for clonal expansion. If not down-regulated, clonal expansion might lead to uncontrolled lymphoproliferation that would be harmful for the organism. Several mechanisms that account for the down-sizing of activated lymphocyte clones are briefly reviewed here. We next consider in detail one such mechanism that deals with the functional characterization and the immunocytochemical localization of two T-cell inhibitory molecules, namely the Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) and the HP-F1 antigen, both present in all T lymphocytes. CTLA-4 and HP-F1 inhibit CD4+ T-helper cell proliferation and the lytic ability of CD8+ T-cytotoxic cells in non-specific and in antigen-specific cytolytic assays. Interestingly, a clonal distribution exists as for the ability of CTLA-4 and HP-F1 to inhibit T-cell functions. In resting and activated T cells, both molecules are largely confined in the endosomal compartment, as shown by immunofluorescence analyses. However, upon interaction of T cells with Antigen-Presenting Cells (APC's) or with target cells that must be killed, CTLA-4 molecules are transported to the plasma membrane, at the site of cell-to-cell contact where, following interaction with ligands, they trigger inhibitory signals.

Ultrastructural study of the conjunctival epithelium in the Mongolian gerbil (Meriones unguiculatus)

The conjunctival epithelium of the Mongolian gerbil (Meriones unguiculatus) was studied using the transmission and scanning electron microscopy. The superficial cells of the conjunctival epithelium were isoprismatic in shape and were covered, on their luminal surface, with microplicae. They were connected with the adjacent cells by junctional complexes and desmosomes. Some of the superficial cells were partially or completely detached from the underlying intermediate cells: this morphological pattern was interpreted as an expression of cellular renewal of the conjunctival surface. Goblet cells were either isolated or gathered in clusters: in any case, they were firmly connected with the adjacent epithelial cells. The apical part of the goblet cells was covered with a great number of long microvilli: they showed a variety of morphological aspects, which were interpreted as occurring in a sequential pattern during the secretory process. The Mongolian gerbil can be considered among the laboratory animals used for ophthalmic research.

Anatomy of the immune system: facts and problems

In the introductory section of this report, the anatomy of the immune system, from organs and tissues to molecules, will be reviewed briefly. Cell proliferation and differentiation in the central lymphoid organs (thymus and bone marrow) yield a repertoire of T- and B-cell clones that seed into peripheral lymphoid organs (spleen, lymph nodes and Mucosa-Associated Lymphoid Tissue, MALT), where humoral and cell-mediated antigen-specific immune responses occur. The stringent process of clonal selection in the central lymphoid organs implies deletion of inappropriate cells via apoptosis. In the peripheral lymphoid organs, the potential of unlimited activation and expansion of lymphocytes in response to antigens is primarily regulated by apoptosis and anergy. These events, on the one hand, are relevant to prevent autoimmunity and lymphoproliferative disorders; on the other hand, clonal deletion and anergy provide a detrimental escape to immune recognition of malignant cells. Two major inhibitory mechanisms of the immune response have emerged recently. One is linked to the existence of bona fide suppressor cells and cytokines; the other relies on the existence of inhibitory molecules expressed by T, B and NK cells, as well as by other leukocytes. In the studies herein reported, emphasis will be given to surface membrane molecules that down-regulate T-cell-mediated immune responses. These molecules control interactions between T cells and antigen presenting cells (APC's) or target (virus-infected or mutated) cells that have to be killed. Two sets of molecules exist that either upregulate (coactivation molecules) or down-regulate (inhibitory molecules) T-cell mediated responses. The latter aspect of the immune regulation, i.e. molecules that limit the expansion of T-cell clones following specific recognition of antigens will be considered in depth. Two inhibitory molecules, CD152 (CTLA-4) and CD85/LIR-1/ILT2 are expressed in all T cells, being largely confined within intracellular compartments of these lymphocytes when they are in a resting state, but ready to be shuttled to and from the plasma membrane when cells are activated following encounter with antigen. Membrane expression of the two inhibitory molecules is transient and is regulated by an internalization process directed to endosomal compartments and to receptor degradation and/or recycling. CTLA-4 and CD85/LIR-1/ILT2 play a pivotal role in T-cell homeostasis that follows any cell-mediated immune response; their localization and functional role will be thoroughly analyzed. In the last part of this study a major question will be faced, i.e. is the containment of the possibly unlimited expansion of the immune system due to a blockade of the cell cycle? Or, else, could be apoptosis the sole mechanism responsible? Experimental data in support of the latter contention will be provided.

The CD85/LIR-1/ILT2 inhibitory receptor is expressed by all human T lymphocytes and down-regulates their functions

The inhibitory molecule CD85/LIR-1/ILT2 has been detected previously on the surface of a small proportion of T lymphocytes. In this study, evidence is provided that, although only a fraction of CD3+ cells are stained by mAb specific for CD85/LIR-1/ILT2 on their surface, this inhibitory receptor is present in the cytoplasm of all T lymphocytes, and that it is detectable on the surface of all T cell clones by the M402 mAb. Biochemical analyses further demonstrate that CD85/LIR-1/ILT2 is present in all T clones analyzed, and that the protein is tyrosine-phosphorylated. Expression of mRNA coding for CD85/LIR-1/ILT2 has been assessed by RT-PCR. Notably, in the NKL cell line and in one T cell clone, amplification of the messenger required 30 cycles only, whereas, in other T cell clones, an amplification product was detected by increasing the number of cycles. CD85/LIR-1/ILT2 inhibits CD3/TCR-mediated activation in both CD4+ and CD8+ clones, and it down-regulates Ag recognition by CD8+ cells in a clonally distributed fashion. Addition of anti-ILT2 HP-F1 mAb in the cytolytic assay enhances target cell lysis mediated by Ag-specific CTL. This could be due to interference of the mAb with receptor/ligand interactions. In contrast, HP-F1 mAb cross-linking triggers inhibitory signals that reduce cytotoxicity. CD85/LIR-1/ILT2 also controls responses to recall Ags and, in low responders, its engagement sharply increases T cell proliferation. The inhibitory function of the molecule is also confirmed by its ability to reduce CD3/TCR-induced intracellular Ca2+ mobilization.

[Treatment of fluid overload and kidney failure with periotoneal dialysis after heart surgery]

BACKGROUND

Infants undergoing cardiac surgery with prolonged cardio-pulmonary bypass are particularly exposed to the risk of acute renal failure for renal hypoxia due to low cardiac output.

METHODS

To limit fluid overload deriving from oligo-anuria and low cardiac output we have recently adopted an early peritoneal dialysis protocol, positioning the peritoneal catheter during the intervention and performing early exchanges at first signs of inadequate diuretic response and/or "leaky capillary syndrome" with diffuse edema. From 1-1 to 31-12-1997 12 patients (8 males), of median age of 65.5 days (range 1-350 days) and median weight of 3463 g (range 2380-6550 g) were treated with peritoneal dialysis (automated exchanges of 10 ml/kg body weight of 1.5% glucose, dwell time 20 minutes). Cardiac pathologies included complex hearth malformations. Cardiopulmonary bypass lasted a mean of 202 minutes (range 102-372 minutes). The children were treated for a minimum of 1 to 42 peritoneal dialysis sessions. The infusional therapy included human albumin and fresh frozen plasma to substitute losses and furosemide at the dose of 4 mg/kg/day to reduce the "leaky capillary syndrome".

RESULTS

The results were very satisfactory: only 3 children died in the first 30 days after surgery. Renal function was normal at the end of the observation in 8/12 cases, and 2 cases presented chronic renal failure.

CONCLUSIONS

Since similar series report a mortality rate of 33-79%, it is suggested that early peritoneal dialysis may have positively influenced the final survival rate.

Echocardiographic assessment of ventricular filling pressure during the second and third trimesters of gestation

AIMS

To confirm changes in the atrioventricular diastolic flow velocities (peak E, peak A, E/A ratio) with gestational age and to define whether these changes genuinely reflect variations in filling pressure in the fetal heart.

METHODS

Fifty normal pregnancies were studied between the 13th and the 37th weeks of gestation. The fetal flow velocity patterns were evaluated by pulsed-wave (PW) Doppler and the annular velocities of the atrioventricular valves by PW-Doppler tissue imaging (DTI).

RESULTS

All indexes evaluated (atrioventricular peak flow and annular velocities) correlated significantly with gestational age. This correlation was stronger for the early diastolic indexes (tricuspid E and EA, 0.69 and 0.78; mitral E and EA, 0.61 and 0.77, respectively) and weaker for the end-diastolic indexes (tricuspid A and AA, 0.46 and 0.37; mitral A and AA, 0.45 and 0.39, respectively). Neither mitral nor tricuspid E/Ea ratio changed significantly with gestational age.

CONCLUSIONS

The lack of correlation between the Doppler-assessed ventricular filling pressures and gestational age suggests absence of significant changes of ventricular compliance during the second and third trimesters of pregnancy, and a progressive enhancement of active relaxation and/or changes in loading conditions.

The ameloblast movement in rat incisor. L.M., S.E.M. and C.L.S.M. study

The internal epithelium of enamel organ and the below enamel surface during growth of the lower incisor, were examinated in ten Wistar rat 12-27 weeks old and weighing between 150/200 gr, by means of immuno histochemical, light and scanning electron microscopy techniques. Our specimens indicate that during the outer enamel secretion the anti-actin positivity goes from distal terminal web to infra nuclear region of cell body. The results of the present study do not support the active movement hypothesis, conversely they support the Warshawsky (1992) hypothesis, i.e. the distal terminal web permits the maintenance and the assembling of ameloblasts during enamel growth. Hence we do agree with Osborn (1970) who reported that, during secretion, ameloblasts move passively in response to secretory forces.

Short-term clinical outcome of patients with acute pulmonary embolism, normal blood pressure, and echocardiographic right ventricular dysfunction

BACKGROUND

The role of echocardiographic right ventricular (RV) dysfunction in predicting clinical outcome in clinically stable patients with pulmonary embolism (PE) is undefined. In this study, we assessed the prevalence and clinical outcome of normotensive patients with RV dysfunction among a broad spectrum of PE patients.

METHODS AND RESULTS

This prospective clinical outcome study included cohort of 209 consecutive patients (age, 65+/-15 years) with documented PE. Acute RV dysfunction was diagnosed in the presence of >/=1 of the following: RV dilatation (without hypertrophy), paradox septal systolic motion, and Doppler evidence of pulmonary hypertension. Four groups were identified: 28 patients presenting with shock or cardiac arrest (13%), 19 hypotensive patients without shock (9%), 65 normotensive patients with echocardiographic RV dysfunction (31%), and 97 normotensive patients without RV dysfunction (47%). Among normotensive patients with RV dysfunction, 6 (10%) developed PE-related shock after admission: 3 of these patients died, and 3 were successfully treated with thrombolytic agents. In comparison, none of the 97 normotensive patients without RV dysfunction developed shock or died as a result of PE.

CONCLUSIONS

A significant proportion (31%) of normotensive patients with acute PE presents with RV dysfunction; these patients with latent hemodynamic impairment have a 10% rate of PE-related shock and 5% in-hospital mortality and may require aggressive therapeutic strategies. Conversely, normotensive patients without echocardiographic RV dysfunction have a benign short-term prognosis. Thus, early detection of echocardiographic RV dysfunction is of major importance in the risk stratification of normotensive patients with acute PE.

Treatment of pulmonary artery stenosis after arterial switch operation: stent implantation vs. balloon angioplasty

The development of pulmonary artery stenosis is a potential complication during the mid- to long-term follow-up after arterial switch operation (ASO) for transposition of the great arteries. Surgical results have been disappointing and conventional balloon dilation yields a fairly important incidence of failures and recurrences. We evaluated our results with implantation of balloon-expandable stents in 5 out of 13 patients with a previously attempted unsuccessful conventional balloon dilation of pulmonary artery branch stenosis after ASO. In two more cases, stents were used as a primary procedure. Balloon angioplasty achieved a 15% increase in mean diameter of the stenosis vs. 124% with the use of stents (P< 0.01), a 10% decrease of the pressure gradient across the stenosis vs. 71% of stents (P<0.01), and a 10% drop in RV/aorta pressure ratio vs. 43% of stents (P<0.01). Compared to conventional balloon angioplasty in our series, stents were more effective in the treatment of patients with peripheral pulmonary artery stenosis after ASO. Balloon dilation should be considered in selected cases unsuitable for treatment with endovascular stents.

Immunofluorescence distribution of actin-associated proteins in human seminiferous tubules of adolescent testes, normal and pathologic

The aim of our study on human seminiferous tubules of adolescent testes was to study the localization of two actin-associated proteins of the adherens junctions, such as vinculin and talin, and to verify if there were modifications in their pattern in varicocele, a frequent disease of the testis in adolescent age. The study group consisted of 8 biopsies from normal testes (i.e., adolescents operated on for hydrocele or inguinal hernia) and 20 biopsies from pathological testes (i.e., adolescents operated on for idiophatic left varicocele). Biopsies were evaluated by indirect immunofluorescence using anti-human vinculin and anti-human talin antibodies. Observation was recorded with a Leica TCS 4D upright confocal microscope. In the normal testes, there was a strong positive immunoreactivity for vinculin, which was localized in the interstitial cells of Leydig, and both basal pole and lateral cell surface of Sertoli cells; the pattern of talin immunoreactivity was the same except that the lateral cell surface of Sertoli cells was not stained. In the varicocele group the pattern was different. Vinculin immunoreactivity showed small patches of fluorescence only in the cytoplasm of Sertoli cells while talin immunoreactivity showed a scanty distribution at the basal surface of Sertoli cells. These results confirm that, similarly to other tissues, vinculin is expressed at cell-cell and cell-matrix adherens junctions, while talin is present at cell-matrix adherens junctions in human seminiferous tubules of normal adolescents. Varicocele alters the patterns of these two proteins both quantitatively and qualitatively.

Ultrastructural and immunohistochemical study of basal lamina of the testis in adolescent varicocele

OBJECTIVE

To evaluate a possible involvement of the extracellular matrix (ECM) in the testes of adolescents with varicocele.

DESIGN

Cross-sectional study.

SETTING

University-based medical center.

PATIENT(S)

Twenty-four adolescents aged between 13 and 18 years underwent surgical treatment for repair of left idiopathic varicocele.

INTERVENTION

A testis biopsy was performed at time of surgery.

MAIN OUTCOME MEASURE(S)

Transmission electron microscopy study of basal lamina and immunofluorescence studies of collagen type IV and laminin, two major components of basal lamina.

RESULT(S)

Transmission electron microscopy observations showed an uneven profile of the basal lamina with a variable thickness. Immunofluorescence studies showed an irregular immunofluorescent line that appeared interrupted in some observations. Collagen type IV showed some areas of strong immunostaining with other areas with reduced immunoreactivity.

CONCLUSION(S)

Our ultrastructural and immunohistochemical observations highlight focal damage at the level of peritubular basal lamina, but this damage is not as severe as that described in adult varicocele. Initial involvement of basal lamina could represent one of the mechanisms responsible for varicocele-induced histologic alterations of the testes.

[Diabetic foot. Physiopathology, clinical aspects, and recent therapeutic approaches]

Diabetic foot is a complication of diabetes mellitus occurring in 15% of patients that is of specific surgical interest. Over the past few years, preventive measures and the use of new therapeutic resources has reduced the number of patients undergoing demolitive surgery. The authors present a concise but at the same time sufficiently detailed picture of modern knowledge of the physiopathology, clinical aspects and current therapeutic guidelines for diabetic foot. In particular, they analyse the validity of various forms of complementary treatment to surgery, including techniques to stimulate tissue repair processes, hyperbaric oxygen therapy and laser therapy, and they underline the importance of using a multidisciplinary approach to this pathology. To this end, they review all the articles on the subject reported on Medline from 1992 to June 1998, presenting and commenting on the most significant results.