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Biomedical subjects

A Calabro

Publications and source records attributed to A Calabro.

At least 37 records · Page 2Linked to original sources
PubMed1996

Epidermal growth factor modulates pepsinogen secretion in guinea pig gastric chief cells.

BACKGROUND & AIMS: Although epidermal growth factor (EGF) inhibits gastric acid secretion, the effects it exerts on gastric chief cells are unknown. The aim of this study was to investigate whether EGF modulates pepsinogen release and intracellular Ca2+ concentrations ([Ca2+]i) and whether the effect involves mitogen-activated protein (MAP) kinase, eicosanoid generation, and nitric oxide. METHODS: Chief cells were obtained by sequential digestion with collagenase and Ca2+ chelation. [Ca2+]i was measured in cells loaded with Fura-2 and NO generation by the NO coproduct citrulline. RESULTS: In situ hybridization, immunohistochemistry, and immunoblotting showed that EGF receptor and MAP kinases were constitutively expressed in chief cells. EGF caused a concentration-dependent stimulation of pepsinogen secretion and MAP kinase activity and determined a 2.5-7.0-fold increase in [Ca2+]i, inositol 1,4,5-tryphosphate, prostaglandin E2, and leukotriene B4. Tyrosine kinase inhibitors and cyclooxygenase and lipoxygenase inhibitors reduced pepsinogen secretion and eicosanoid generation induced by EGF. EGF increased citrulline generation and guanosine 3',5'-cyclic monophosphate accumulation sixfold; the effect was blocked by NG monomethyl-L-arginine, which is an NO synthase inhibitor. CONCLUSIONS: EGF stimulates pepsinogen secretion by activating eicosanoid generation, tyrosine kinases, MAP kinases, Ca2+, NO, and guanosine 3',5'-cyclic monophosphate.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1996

Clinical pharmacokinetics of amonafide (NSC 308847) in 62 patients.

Amonafide (A) demonstrates dose-related increases in area under the curve (AUC) and Cmax values. Total body clearance for A (ranging from 44.2 to 53.8 L/hr/m2) is relatively constant within the dosing range of this study. The dose-related increase of AUC was also observed for the two identified metabolites, acetylamonafide (AA) and noramonafide (NA). A and NA plasma data could be described by a four-compartmental model (two compartments for A, one compartment each for NA and AA). The fitting for NA was poor owing to its low plasma concentration. The terminal half-lives for A, NA, and AA were in the range of 3-6 hr. No cumulative accumulation of parent compound or metabolites was detected after daily administration, The concentrations of A, NA, and AA 24 hr after dosing were either below or very close to the quantitative limits of the assay. Polymorphic disposition of A was confirmed by a frequency distribution of AUC value versus dose plot.

Adenine↗
PubMed1996

Self-injection devices for intracavernosal pharmacotherapy: operational classification and safety considerations.

Several self-injection devices have been recently proposed as an aid to home intracavernosal self-injection treatment for erectile dysfunction, with the purpose of allowing an easier drug administration, decreasing the artificiality of intracavernosal pharmacotheraphy, with the overall goal of increasing the acceptability of this treatment. We propose a classification of these devices according to the type of mechanical impact on the cavernosal tissue: self-injection pens, allowing for manual needle insertion and manual drug delivery; autoinsertors, with automatic needle insertion and manual drug delivery, and autoinjectors, that provide both automatic needle insertion and automatic drug delivery. The use of autoinjectors bears two theoretical risks: extra-corporal drug delivery in cases of wrong injection site, and trabecular damage due to high delivery pressure. In one device pressures 15 times higher the values reached by manual injection, and statistically higher than pressures obtained by maximal strength manual injection, were observed in an in-vitro investigation. Specific studies are needed to define a threshold pressure value for trabecular damage in the flaccid state; accordingly, information on autoinjector developed pressures should be provided by manufacturers. Clinical studies with adequate follow-up are needed as well, to verify the risk of autoinjector-induced extracorporal drug delivery, and the occurrence of intracavernosal nodules or penile curvature, compared to manual self-injection.

Adult↗
PubMed1995

Nonreducing end structures of chondroitin sulfate chains on aggrecan isolated from Swarm rat chondrosarcoma cultures.

Chondrocyte cultures derived from the Swarm rat chondrosarcoma were metabolically labeled with [35S]sulfate or [6-3H]GlcN. Radiolabeled aggrecan was purified from the cell layer and exhaustively digested with chondroitin ABC lyase. Digestion products were resolved into disaccharide and monosaccharide residues using Toyopearl HW40S chromatography. The separated saccharide pools were reduced with NaBH4 and applied onto a CarboPac PA1 column to resolve all of the internal disaccharide alditols (unsaturated) from the nonreducing end disaccharide (saturated) and monosaccharide alditols. Mercuric acetate treatment was used prior to carbohydrate analysis to identify unambiguously the saturated from the unsaturated disaccharides. The chondroitin sulfate (CS) chains from these aggrecan preparations contained: (a) an internal disaccharide composition of unsulfated (3-4 per chain), 4-sulfated (approximately 32 per chain), 6-sulfated (approximately 1 per 14 chains), and 4,6-sulfated disaccharides (approximately 1 per 6 chains) and (b) a nonreducing terminal composition of 4-sulfated GalNAc (approximately 4 out of every 7 chains), 4,6-disulfated GalNAc (approximately 2 out of every 7 chains), and GlcUA adjacent to a 4-sulfated GalNAc residue (approximately 1 out of every 7 chains). Thus, the vast majority of these CS chains terminated with a sulfated GalNAc residue. The presence of 4,6-disulfated GalNAc at nonreducing termini is 60-fold more abundant than 4,6-disulfated GalNAc in interior disaccharides. This observation is consistent with the suggestion that disulfation of terminal GalNAc residues is involved in chain termination.

Aggrecans↗
PubMed1994

Differential effects of brefeldin A on chondroitin sulfate and hyaluronan synthesis in rat chondrosarcoma cells.

Brefeldin A, a fungal metabolite, interferes with vesicular transport causing disassembly of the Golgi complex with redistribution of Golgi components to the endoplasmic reticulum, and isolation of the trans-Golgi cisternae from the trans-Golgi network. We examined the effects of brefeldin A on the synthesis of hyaluronan and chondroitin sulfate by chondrocytes from the Swarm rat chondrosarcoma. Hyaluronan synthesis continues at a constant rate in the presence of brefeldin A for at least 8 h, and is therefore independent of vesicular transport. By contrast, chondroitin sulfate synthesis is rapidly inhibited (to < 1% within 15 min) by brefeldin A indicating that addition of chondroitin sulfate chains to the aggrecan core protein precursor requires vesicular transport. Removal of brefeldin A rapidly restored chondroitin sulfate chain elongation and sulfation on the aggrecan core protein precursor reaching 100% of control in 2 h and consistently establishing a higher steady state rate (up to 120%) by 4 h. Addition of p-nitrophenyl-beta-D-xylopyranoside, an exogenous acceptor for the synthesis of chondroitin sulfate chains, does not reverse the brefeldin A block. This suggests that xyloside-initiated synthesis of chondroitin sulfate depends on transport vesicles as might occur if the enzymes for synthesizing the linkage tetrasaccharide (i.e. galactosyltransferases) reside in the Golgi, while those required to elongate the chains reside in the trans-Golgi network. Recovery of chondroitin sulfate synthesis from brefeldin A treatment occurred efficiently in the presence of cycloheximide, indicating that the machinery for chondroitin sulfate synthesis reassembles from previously existing proteins. The results are consistent with the current model that hyaluronan synthesis occurs at the plasma membrane and is independent of vesicular transport, and with the hypothesis that the enzyme complex for chondroitin sulfate elongation and sulfation residues within the trans-Golgi network, and therefore isolated from the aggrecan core protein precursor in the presence of brefeldin A.

Animals↗
PubMed1994

Effects of brefeldin A on aggrecan core protein synthesis and maturation in rat chondrosarcoma cells.

In this paper, the effects of the fungal metabolite, brefeldin A, on the synthesis and maturation of aggrecan core protein precursor were studied in rat chondrosarcoma chondrocytes. The aggrecan core protein precursor was partially identified in total protein pools isolated from cell extracts based on its selective cleavage at a single site by the restriction protease factor Xa. During a 2-h labeling period with [3H]serine as precursor, brefeldin A inhibited the synthesis of mature aggrecan from its aggrecan core protein precursor consistent with an inhibition of chondroitin sulfate chain elongation and sulfation as described in the accompanying paper (Calabro, A., and Hascall, V. C. (1994) J. Biol Chem. 269, 22764-22770). This inhibition is presumably the result of the disruption of vesicular transport by brefeldin A, which isolates the aggrecan core protein precursor at the level of the trans-Golgi cisternae from the enzymes for chondroitin sulfate chain elongation and sulfation located in the trans-Golgi network. Brefeldin A also inhibited the exocytosis of all radiolabeled secretory proteins from the cell layer into the medium compartment, which is also consistent with the disruption of vesicular transport attributed to this metabolite. Although total protein synthesis was inhibited by 12% in the presence of brefeldin A, the aggrecan core protein precursor accumulated within the cell layer indicating that the inhibition of chondroitin sulfate synthesis by brefeldin A was not the result of a lack of aggrecan core protein precursor. When the brefeldin A block was removed and cultures chased in the presence of cycloheximide to prevent new protein synthesis, vesicular transport through the cell was re-established and chondroitin sulfate chains were added to a large proportion of the aggrecan core protein precursor that had accumulated during the brefeldin A block. These results suggest that the machinery for chondroitin sulfate synthesis and for protein exocytosis, that were disrupted by brefeldin A treatment, recover after removal of the brefeldin A, even in the presence of cycloheximide, and that the structures involved in these processes reassemble from previously existing proteins. Interestingly, two other proteins with the same relative abundance as the aggrecan core protein precursor were observed. An approximately 210-kDa protein with the characteristics of the fibronectin subunit, and an unidentified approximately 150-kDa protein which was efficiently cleaved by the protease Xa enzyme.

Aggrecans↗
PubMed1994

X-linked mental retardation, microcephaly, and growth delay associated with hereditary bullous dystrophy macular type: report of a second family.

We report on 2 patients with mental retardation and bullous dystrophy, macular type. The observation of the condition in a male and his maternal uncle is consistent with recessive X-linkage. Due to the rarity of the condition, nosologic definition was difficult before the birth of the propositus. The clinical picture in the two patients described, characterized by mental retardation, dwarfism, microcephaly, alopecia, bullous dystrophy macular type, hypogenitalism, is very much like the one observed in the patients, all males, belonging to the only other family reported to date. The recent localization of the bullous dystrophy gene in the Xq24-qter segment opens the possibility of prenatal diagnosis.

Abnormalities, Multiple↗
PubMed1994

Carotid artery endarterectomy in patients with contralateral carotid artery occlusion: perioperative hazards and late results.

The aim of this study was to analyze and compare the perioperative hazards and late results of internal carotid endarterectomy (CEA) in patients with and without contralateral internal carotid artery occlusion. From March 1980 to April 1990, 375 consecutive patients underwent 439 CEAs at the First Department of Vascular Surgery of Padova Medical School. Patients were divided into two groups; group 1 (61 patients) had contralateral internal carotid artery occlusion and group 2 (314 patients) did not (378 CEAs, 64 bilateral). Indications for CEA were similar in both groups. The only significant difference in patient characteristics was a higher rate of previous stroke in group 1 (11% vs. 3%, p < 0.001). General anesthesia, continuous EEG monitoring, selective intraluminal shunt, and arteriotomy closure with a polytetrafluoroethylene patch (PTFE) were used routinely in both groups. An intraluminal shunt was inserted more frequently in group 1 than in group 2 (69% vs. 17%, p < 0.001). Major perioperative stroke occurred in one patient in each group (1.7% vs. 0.31%, respectively; NS). Early fatal stroke rates were 0% and 0.95% in groups 1 and 2, respectively (NS). All patients had neurologic examinations and duplex scans every 6 months (range 6 to 118 months; mean 42 months). Kaplan-Meier survival curves were virtually identical in the two groups; the majority of deaths were caused by myocardial infarction and cancer. There were no stroke-related deaths in group 1 as compared with 8.2% in group 2 (NS). New neurologic symptoms appeared in 4.7% of patients in group 1 and 6% in group 2 (NS) whereas the late stroke rates were 0% and 3.1%, respectively (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

High-resolution separation of disaccharide and oligosaccharide alditols from chondroitin sulphate, dermatan sulphate and hyaluronan using CarboPac PA1 chromatography.

Recent literature indicates that specific glycosaminoglycan structures are involved in various biological processes, such as anticoagulation, growth factor activation and viral infection. The initial step in the structural analysis of glycosaminoglycans is a definitive compositional analysis of its characteristic disaccharide repeat structures. Current chromatographic or electrophoretic procedures may have limitations in analysing glycosaminoglycan samples that are in low abundance, contain novel structures that need to be further characterized, or are metabolically labelled from radioactive precursors as a result of biosynthetic experiments. This study presents a new methodology for analysing disaccharides and oligosaccharides derived from chondroitin sulphate, dermatan sulphate and hyaluronan that fulfils the above criteria. The procedure involves the separation of reduced forms of these glycoconjugates on a CarboPac PA1 column using alkaline eluants. This study adopted a strategy which uses specific enzymes to release these disaccharides from their glycosaminoglycan forms. A borohydride reduction reaction was modified to be compatible with the buffer conditions commonly used with these enzymes in order to quantitatively reduce the disaccharides to their alditol forms (thereby stabilizing them to alkaline pH). Chromatography conditions were established which separated all known disaccharide alditol structures from chondroitin sulphate, dermatan sulphate and hyaluronan with extremely high resolution in a single run. Integrated pulsed amperometry was compared to UV absorbance measurement at 232 nm as two sensitive methods for detecting these reduced disaccharides; most of them could be routinely detected in the range of 50-500 ng. Data are presented applying this method to quantify hyaluronan in a biological sample which contains approximately 5000 cells and only approximately 10 ng of hyaluronan. Additional data are presented to demonstrate that this procedure will also separate oligosaccharide alditols derived from hyaluronan.

Borohydrides↗
PubMed1994

Human polyreactive and monoreactive antibodies: effect of glycosylation on antigen binding.

The present experiments were initiated to determine whether the carbohydrate portions of antibody molecules contribute to polyreactivity. Cell lines making human monoclonal polyreactive or monoreactive antibodies of the immunoglobulin (Ig) M, IgG and IgA isotypes were treated with tunicamycin to block N-linked glycosylation of the proteins. Analysis of the secreted native and non-glycosylated proteins revealed a > 95% inhibition of [3H]mannose incorporation. Electrophoresis on sodium dodecyl sulphate-polyacrylamide gels of the proteins from tunicamycin-treated cells showed increased mobility and the absence of [3H]mannose incorporation of the immunoglobulin heavy chains, consistent with the lack of glycosylation. The native and non-glycosylated antibodies were then tested for their ability to bind different antigens. Despite the lack of glycosylation, both polyreactive and monoreactive antibodies bound to antigens with little if any loss of reactivity or specificity. It is concluded that the carbohydrate moieties do not contribute significantly to polyreactivity.

Antibodies, Bispecific↗
PubMed1993

Analysis of water-macromolecule proton magnetization transfer in articular cartilage.

These studies were designed to establish which structural elements of cartilage are responsible for proton magnetization transfer between water (Hf) and macromolecules (Hr) observed in MRI studies on articular cartilage. Saturation transfer techniques were used to monitor magnetization transfer in vitro on samples of the two major constituents of cartilage: collagen and proteoglycan. Articular cartilage samples were also evaluated in vitro before and after the removal of the proteoglycan fraction. Isolated hydrated collagen exhibited a significant proton magnetization transfer rate with water. In contrast, proteoglycans exhibited no proton magnetization transfer. Articular cartilage, in vitro, exhibited a high degree of magnetization transfer with water protons consistent with previous MRI studies in vivo. Enzymatic removal of proteoglycan from the cartilage did not alter the magnetization transfer rate between Hr and Hf. These data demonstrate that the structure and concentration of the collagen matrix are the predominant determinants of the magnetization transfer process in articular cartilage with little or no contribution from proteoglycans. This specificity of the magnetization transfer effect may prove useful in the noninvasive evaluation of cartilage composition and structure in vivo.

Animals↗
PubMed1993

Omphalocele and gastroschisis: a collaborative study of five Italian congenital malformation registries.

During 1984-1989, 116 cases of omphalocele and 42 cases of gastroschisis were detected among 736,760 consecutive births in the area covered by five Italian congenital malformation registries. The prevalence rate was 1.6 per 10,000 for omphalocele and 0.6 per 10,000 for gastroschisis. Three additional cases were detected among spontaneous abortions, giving a total of 117 cases of omphalocele and 44 of gastroschisis. No variations in prevalence rates were observed among registries. A cluster of omphalocele was found in 1989 in Firenze. All cases were sporadic except for one infant with two sibs with Beckwith-Wiedemann syndrome. A predominance of male infants was observed for both defects. This study confirms the very young maternal age for isolated gastroschisis as compared to that for omphalocele and controls. Birth weight and the percentage of small-for-date is different among isolated gastroschisis, omphalocele and controls. Associated anomalies occurred in 45 cases of omphalocele and 11 cases of gastroschisis. Our data confirm the association of omphalocele with trisomies 13 and 18. Twelve cases of omphalocele and gastroschisis with associated limb defects were classified as limb body wall complex. The possible differences in etiopathology between omphalocele and gastroschisis, both isolated and associated, are discussed.

Abnormalities, Multiple↗
PubMed1993

Uronic acid-containing glycosaminoglycans and keratan sulfate are present in the tectorial membrane of the inner ear: functional implications.

The tectorial membrane is a gel-like, acellular connective tissue overlying the microscopic organ of Corti--the auditory sensory structure. It is instrumental in the sound-synchronous deflection of the stereocilia of the hair cells, a central event in auditory transduction. It is well established that collagen, primarily type II, constitutes the major protein of the tectorial membrane, with smaller amounts of types IX and XI also present. However, conclusive information on the proteoglycans in this structure is lacking. Tectorial membranes were extracted with a 4 M guanidine--HCl solvent, and proteoglycans isolated after ethanol precipitation and collagenase treatment. A colorimetric assay based on the binding of the cationic dye safranin O to glycosaminoglycans, in combination with enzymatic techniques, detected significant amounts of chondroitin sulfate and keratan sulfate (0.29 and 0.17% on a wet weight basis, respectively). Agarose-polyacrylamide electrophoresis of chondroitinase-digested samples revealed a core protein with a similar molecular mass to that of the large cartilage proteoglycan aggrecan. This proteoglycan reacted with the antibody 3-B-3 (recognizing modified chondroitin 6-sulfate linkage region oligosaccharides). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed several low molecular mass proteins which reacted with 5-D-4, specific for keratan sulfate, one of which showed characteristics of fibromodulin. Comparison of the quantitative aspects of various connective tissue components of tectorial membrane with other type II collagen-containing structures revealed that this tissue resembles highly hydrated cartilage.

Animals↗
PubMed1993

Electrical stimulation of the dorsal nerve of the penis evokes reflex tonic erections of the penile body and reflex ejaculatory responses in the spinal rat.

An animal model using the spinal rat was characterized. Electrical stimulation of the dorsal nerve of the penis elicited reflex tonic erections of the penile body and reflex bulbospongiosus muscle activity, flips and ejaculations. The tonic erections of the penile body are independent from contractions of the bulbospongiosus muscle and appear to be the result of a neurovascular process. Our observations suggest that reflex bulbospongiosus muscle activity, flips and ejaculations are a single complex reflex response, which we define as reflex ejaculatory response. Two parameters predicted the occurrence and type of reflex response. The visualization of bulbospongiosus muscle activity during surgical isolation of the dorsal nerve of the penis was sufficient to anticipate the elicitability of reflex ejaculatory responses. The latter, together with a systemic systolic pressure > or = 73 mmHg., warranted the elicitability of reflex tonic erections. The similarities found in the physiology of rat tonic penile body erections and of human erections make this model promising for further elucidation of sexual function. Moreover, the present model may prove useful for the investigation of neurogenic erectile dysfunction, and of neurogenic ejaculatory disorders.

Animals↗