Synthesis and conformational study in solution and in solid state of oligopeptides containing l-leucine and glycine

The synthesis and conformational studies of the oligopeptide N-tert.-butyloxycarbonyl-l -Leu-(l -Leu-Gly)_n-OBzl (n = 1, 3, 5) and N-tert.-butyloxycarbonyl-(l -Leu-Gly)₂-OBzl are described. The peptides were synthesized by stepwise and fragment condensation techniques using dicyclohexylcarbodiimide as the condensing agent in solution. The conformational study of the oligopeptides was carried out using CD, u.v. and i.r. spectra. The conformation in solution was examined in trifluoroethanol, hexafluoroisopropanol. hexafluoroacetone trihydrate, and methanol. CD spectra in trifluoroethanol exhibited a gradual variation with increasing peptide chain length. This can be interpreted as a formation of an ordered structure which is already present in the heptapeptide and, to a greater extent, in the undecapeptide. The results obtained from the CD profiles and i.r. spectra showed the presence of β structure with antiparallel chains in the heptapeptide and undecapeptide. Finally, CD spectra revealed in trifluoroethanol-water solution the binding of Ca²⁺ to heptapeptide and undecapeptide together with a contemporaneous conformational change. This change is probably due to the formation of β-turns. No change in the CD profiles was obtained by using Mg²⁺, K⁺, Na⁺, and Li⁺ ions instead of Ca²⁺.     

Allogeneic bone marrow transplantation versus chemotherapy in high-risk childhood acute lymphoblastic leukaemia in first remission

We compared the outcome of children with high-risk acute lymphoblastic leukaemia (HR-ALL) in first complete remission (first CR) treated with chemotherapy (CHEMO) or with allogeneic bone marrow transplantation (BMT) in a multicentre study.   All children treated by the Italian Paediatric Haematology Oncology Association for HR-ALL in first CR between 1986 and 1994 were eligible for the study. 30 children were given BMT at a median of 4 months from first CR, with preparative regimens including total-body irradiation ( n  =25/30). 130 matched controls for BMT patients were identified among 397 HR-ALL CHEMO patients. Matching on main prognostic factors and duration of first CR was adopted to control the selection and time-to-transplant biases. The comparative analysis was based on the results of a stratified Cox model. The estimated hazard ratios of BMT versus CHEMO at 6 months, 1 year and 2 years after CR were 1.38 (CI 0.59–3.24), 0.69 (CI 0.27–1.77) and 0.35 (CI 0.06–1{\raise 5mu ..91), with an overall non-significant difference between the two groups ( P  = 0.34). With a median follow-up of 4 years, the disease-free survival was 58.5% (SE 9.3) in the BMT group and 47.7% (SE 4.8) in the CHEMO group, at 4 years from CR. Non-leukaemic death occurred in 4% of CHEMO and 10% of BMT patients. In the BMT group the estimated cumulative incidence of relapse at 1.5 years from CR was 31.5% (SE 8.8) and did not change thereafter, whereas in the CHEMO group the corresponding figure was 29.2% (SE 4.1) and the incidence continued to increase thereafter (48.2% (SE 4.8) at 4 years from CR).   The results of this study suggest that, with respect to the CHEMO group, the higher risk of early failure in the BMT group is outweighed by the lower risk of relapse after 1 year. Results prompt the need for a prospective study, in order to demonstrate the likely advantage of BMT in HR childhood ALL in first CR.     

The cells of the rabbit meniscus: their arrangement, interrelationship, morphological variations and cytoarchitecture

Four major morphologically distinct classes of cells were identified within the adult rabbit meniscus using antibodies to cytoskeletal proteins. Two classes of cell were present in the fibrocartilage region of the meniscus. These meniscal cells exhibited long cellular processes that extended from the cell body. A third cell type found in the inner hyaline-like region of the meniscus had a rounded form and lacked projections. A fourth cell type with a fusiform shape and no cytoplasmic projections was found along the superficial regions of the meniscus. Using a monoclonal antibody to connexin 43, numerous gap junctions were observed in the fibrocartilage region, whereas none were seen in cells either from the hyaline-like or the superficial zones of the meniscus. The majority of the cells within the meniscus exhibited other specific features such as primary cilia and 2 centrosomes. The placement of the meniscal cell subtypes as well as their morphology and architecture support the supposition that their specific characteristics underlie the ability of the meniscus to respond to different types of environmental mechanical loads.     

In vitro interactions of opioid peptides with phospholipids

The interaction of leu-enkephalin with phosphatidylserine has been studied with ultraviolet and circular dichroism spectroscopy methods as well as with fluorescence anisotropy techniques. The data reported hereunder confirm the existence of binding between the two species, and also support the hypothesis that not only the tyrosine, but also the phenylalanine residue in the leu-enkephalin molecule is involved in peptide-lipid interaction. In addition, ultraviolet and CD evidence, taken together, tend to suggest that both aromatic residues are bound, with a different degree of involvement, to the same region of the lipid molecule. The data reported are discussed in terms of the interaction model previously proposed by us.     

ANTIPYRINE CLEARANCE IN CONGENITAL ADRENAL HYPERPLASIA

Antipyrine (AP) metabolism was studied in four adult patients with congenital adrenal hyperplasia (CAH) due to classical 21-hydroxylase deficiency and in four (adult) patients with CAH due to non-classical 21-hydroxylase deficiency. This investigation was prompted by the known biochemical and functional similarities between drug- and steroid-metabolizing enzymes. We hypothesized that a common genetic mechanism may regulate the expression and activity of both the adrenal and hepatic cytochrome P450 enzymes. AP half-lives (T1/2, mean +/- SD) were 10.7 +/- 2.1 h in classical CAH patients, 10.1 +/- 0.4 h in the nonclassical CAH patients and 10.9 +/- 2.2 h in the control group, suggesting that there was no significant difference in AP metabolism among the three groups. Similarly, no significant differences were found in the AP apparent volume of distribution (aVd) and metabolic clearance rate (MCR) among the three groups. These results indicate that despite the deficiency of adrenal cytochrome P450 in patients with 21-hydroxylase deficiency CAH, these individuals have normal hepatic drug metabolizing activity for the biotransformation of AP.     

Synthesis of human angiotensinogen (1-17) containing one of the putative glycosylation binding sites and its hydrolysis by human renin and porcine pepsin

The N-terminal heptadecapeptide of human angiotensinogen (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu-Val-Ile-His-Asn-Glu-Ser-Thr-NH₂), with the C-terminal carboxyl group amidated, was synthesized in order to study the role of Asn-Glu-Ser, a putative carbohydrate binding site, on the hydrolysis by human renin. The synthesis was performed by fragment condensation using the Honzl and Rudinger azide procedure. In our conditions for azide segment condensation, histidine racemization was demonstrated to be negligible for most of the condensation reactions. Human renin liberates angiotensin I from h-angiotensinogen (1-17)-NH₂ with a K_m value of 3.4 × 10^?5m , at pH 7.3 and 37° being similar to h-angiotensinogen (1-13), an analog without the carbohydrate binding site. However, the V_max value of 4.1 × 10^?9mol/G.U. min is one order of magnitude higher. Porcine pepsin was demonstrated to cleave preferentially Leu¹⁰-Val¹¹ bond and, surprisingly, His⁹-Leu¹⁰ as well.     

Atrial Arrhythmias in Long-QT Syndrome under Daily Life Conditions: A Nested Case Control Study

Background: The long-QT syndromes (LQTS) are inherited electrical cardiomyopathies characterized by prolonged ventricular repolarization and ventricular arrhythmias. Several genetic reports have associated defects in LQTS-causing genes with atrial fibrillation (AF). We therefore studied whether atrial arrhythmias occur in patients with LQTS under daily-life conditions.
Methods: We systematically assessed atrial arrhythmias in LQTS patients and matched controls using implanted defibrillators or pacemakers as monitors of atrial rhythm in a nested case-control study. Twenty-one LQTS patients (3 male; 39 ± 18 years old; 18 on β blocker, ICD therapy duration 6.3 ± 2.7 years; 4 LQT1, 6 LQT2, 2 LQT3) were matched to 21 control subjects (13 male; 50 ± 19 years old; 3 on β blocker; pacemaker therapy duration 8.5 ± 5.5 years; 19 higher-degree AV block, 2 others). LQTS patients were identified by a systematic search of the LQTS patient databases in Münster and Munich.
Results: One-third (7 of 21) of the LQTS patients developed self-terminating atrial arrhythmias (atrial cycle lengths <250 ms). Only one control patient developed a single episode of postoperative AF (P < 0.05 vs LQTS).
Conclusions: LQTS patients at high risk for ventricular arrhythmias may develop short-lasting atrial arrhythmias under daily-life conditions, suggesting that prolonged atrial repolarization may contribute to the initiation of AF.     

Anomalous Mitral Arcade: Echocardiographic and Color Flow Findings

A patient with surgically confirmed anomalous mitral valve arcade was noninvasively studied. Two-dimensional echocardiography clearly visualized the "arcade" shape and Doppler color flow mapping was useful in assessing hemodynamics. (ECHOCARDIOGRAPHY, Volume 8, November 1991)     

Thin Primary Cutaneous Melanoma in Childhood and Adolescence: Report of 12 Cases

Abstract:  Approximately, 1–4% of all new melanoma cases occur in patients younger than 20 years. The clinical presentation of melanoma in the young is often challenging. We report the experience of the Melanoma Unit of University Hospital Spedali Civili of Brescia, Italy. Study subjects were drawn from 1470 patients with histologically confirmed melanoma. From this group, melanoma developed in 12 patients younger than 19 years. For each melanoma diagnosed, histologic characteristics, treatment, and outcomes were evaluated. Of the 12 patients described in this study, four were men and eight were women. The average age was 15.6 years ranging from 11 to 18 years. Regarding invasive melanomas, Breslow thickness ranged from 0.15 to 0.66 mm with a mean thickness of 0.36 mm. Primary treatment of 12 patients included wide local excision of their primary lesions. In many cases reported in literature lesions are amelanotic, nodular, and resemble pyogenic granuloma. From our case studies it was found that the clinical characteristics detected in melanomas diagnosed in childhood and adolescence have been the same as those described in adults and that the ABCDE clinical criteria may be helpful basics of melanoma.