Endotoxin activity of collagenase and human islet transplantation.
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Collagenases↗
Biomedical subjects
F Vargas
Publications and source records attributed to F Vargas.
Genetic disorders in normally androgenized infertile men and the use of intracytoplasmic sperm injection as a way of treatment.
OBJECTIVE: To determine the incidence of chromosomal abnormalities in normally androgenized infertile men with no other recognized causes of infertility or who had ever been submitted to other unsuccessful methods of treatment. DESIGN: Collaborative retrospective study of clinical experience collected by an endocrinologist and a geneticist over a 5-year period. SETTING: Outpatients at an endocrinology clinic. PATIENT(S): Infertile male patients with azoospermia (n = 23), oligozoospermia (n = 66), and normozoospermia (n = 14) presenting normal (n = 85) or subnormal (n = 18) testicular volume. INTERVENTION(S): All patients were submitted to cytogenetic analysis. MAIN OUTCOME MEASURE(S): Two patients were referred to intracytoplasmic sperm injection (ICSI), and in one case, a successful gemellar pregnancy ended up uneventful. Children's genetic testing were not performed according to parents' request. RESULT(S): Abnormal karyotypes were found in 11 (10.6%) patients. Chromosomal abnormalities were found in 17.3% of the 23 azoospermic patients, in 10.6% of the 66 oligozoospermic patients, and in none of the 14 normozoospermic patients. These disorders were found only in patients with normal testicular volumes and no more than 10 x 10(6) spermatozoa per mL. CONCLUSION(S): A high incidence of chromosomal abnormalities was found in a selected group of normally androgenized infertile male patients. The elevated rate of fertilization achieved in one patient indicates that ICSI is, at the moment, the only choice for treatment of male infertility because of chromosomal abnormalities.
Chromosome Aberrations↗
Abnormal renal vascular reactivity to acetylcholine and nitroprusside in aging rats.
1. The actions of acetylcholine (ACh), CaCl2 and nitroprusside (NP) were studied in aortic strips and in the perfused kidneys from adult (4-6 months old) and aging (23-24 months old) rats. 2. ACh and CaCl2 produced a dose-related relaxation in aortic strips from adult and old rats; maximal responses to both vasodilators were significantly reduced (ACh: adult = 66.4 +/- 6.1%, Old = 27.1 +/- 5.7%, P < 0.001; CaCl2: adult = 75.6 +/- 3.9%, Old = 54.1 +/- 4.1%, P < 0.01) in aortas from old rats. NP-evoked relaxation was not significantly different between the two groups. 3. In kidneys from adult rats, ACh produced dose-related decreases in renal perfusion pressure (RPP), whereas, in kidneys from old rats, ACh produced a dose-related decrease at low doses, and biphasic responses (vasodilatation followed by vasoconstriction) at medium to high doses, with a reduced vasodilator component. Vasodilator response to ACh to the highest dose; ACh; adult = 78.7 +/- 2.8%, Old = 40.6 +/- 2.6%, P < 0.001). In kidneys from adult rats, NP produced a dose-related decrease in RPP. However, in kidneys from old rats, NP produced vasoconstriction at low doses, biphasic responses at medium doses (vasoconstriction followed by vasodilation), and vasodilation at the highest dose. 4. The results of the present study demonstrated that: (a) The isolated perfused kidney from aging rats had a dual response (with an important vasoconstrictor component) to ACh and NP, which may be due to the release of a nonprostanoid vasoconstrictor or to abnormalities in the renal vascular smooth muscle. In contrast, in aortic-strips from old and adult rats, these agents only caused relaxation; (b) aging is accompanied by reduced endothelium-dependent relaxation both in large arteries and in resistance vessels; and (c) large arteries from aging rats require a higher concentration of extracellular calcium to stabilize the membrane of smooth muscle cells.
Acetylcholine↗
Mutations in the C-terminal domain of Sonic Hedgehog cause holoprosencephaly.
Holoprosencephaly (HPE) is the most common brain anomaly in humans, involving abnormal formation and septation of the developing central nervous system. Among the heterogeneous causes of HPE, mutations in the Sonic Hedgehog (SHH) gene have been shown to result in an autosomal dominant form of the disorder. Here we describe a total of five different mutations in the processing domain encoded by exon 3 of SHH in familial and sporadic HPE. This is the first instance in humans where SHH mutations in the domain responsible for autocatalytic cleavage and cholesterol modification of the N-terminal signaling domain of the protein have been observed.
Alanine↗
Renal and vascular actions of equol in the rat.
BACKGROUND: The urinary isoflavonoid equol inhibits membrane Na-K-Cl cotransporters at similar concentrations to those at which furosemide inhibits them, but the significance of this action is not known. OBJECTIVE: To investigate the potential salidiuretic and vascular actions of equol in the rat. METHODS: Renal functioning was assessed in vitro in the isolated perfused kidney and in vivo in conscious rats. The vascular contractility of isolated aorta was assessed. RESULTS: In the isolated perfused kidney equol was concentrated 50- to 70-fold in the urinary fluid, it was 3-4 times less potent than furosemide at increasing diuresis, natriuresis and kaliuresis (the difference was due to its higher protein-binding affinity), and it induced a modest but significant increase in glomerular filtration rate. In vivo, orally administered equol was a modest natriuretic agent, about 8-fold less potent than orally administered furosemide (in molar terms). In isolated aortic rings precontracted by administration of phenylephrine, administration of equol relaxed the contracted aorta at 10-fold lower concentrations (concentration for half-maximal activity 58.9 +/- 16 micromol/l, n = 3) than did furosemide (concentration for half-maximal activity 633 +/- 145 micromol/l, n = 3). CONCLUSIONS: Equol is a modest natriuretic and vasorelaxant agent in the rat. Further studies are required in order to investigate the potential natriuretic and perhaps hypotensive actions of dietary equol precursors (daidzein).
Animals↗
Proteasome subunits, low-molecular-mass polypeptides 2 and 7 are hyperexpressed by target cells in autoimmune thyroid disease but not in insulin-dependent diabetes mellitus: implications for autoimmunity.
Autoimmune thyroid diseases (AITD) and insulin-dependent diabetes mellitus (IDDM) are two autoimmune syndromes of unknown etiology with common immune features. One is that the target cells, thyrocytes and pancreatic islet beta cells respectively, hyperexpress several proteins encoded in the HLA region: HLA class I, HLA class II and transporter associated with antigen processing (TAP-1): the clinical course and many aspects of the immunopathology are, however, quite different. Low-molecular-mass polypeptides 2 and 7 (LMP2 and LMP7) are proteasome subunits that increase the efficiency of endogenous antigen processing and are encoded in close vicinity to the TAP genes. We investigated whether LMP2 and LMP7 are hyperexpressed in thyrocytes and islet cells in AITD and IDDM. Thyroid tissue from Graves' disease patients (GD, n = 8) and Hashimoto thyroiditis (HT, n = 1) and pancreatic tissue from IDDM patients (n = 4) as well as control tissues were examined by the two-color indirect immunofluorescence technique. The results demonstrate that, in normal glands, thyrocytes and pancreatic islet cells express comparable moderate to low levels of LMP2 and LMP7. In AITD and IDDM, expression of LMP2/7 in the endocrine cells was disparate: while in AITD glands there was hyperexpression of LMP2 and 7 parallel to that of HLA class I and TAP-1, in the islet cells of recent onset diabetic pancreases (n = 2) the level of LMP2 and 7 expression was totally normal, including islets that were infiltrated by lymphocytes and hyperexpressed HLA class I and TAP-1. These observations suggest different mechanisms of endogenous peptides generation at the target cells in AITD from IDDM. Since this is a key step for the maintenance of peripheral tolerance, it may help to understand some of the different clinical features of the two autoimmune diseases.
Adolescent↗
Age-related changes in the pressure diuresis and natriuresis response.
The renal-excretory responses to changes in renal perfusion pressure (RPP) were studied in anesthetized young (3 mo old), adult (12 mo old), and senescent (24 mo old) rats to evaluate whether the pressure diuresis and natriuresis mechanism is altered as a function of age. Experiments were performed in anesthetized animals in which nervous and systemic hormonal influences to the kidney were fixed. Mean arterial pressure was similar in all three groups: 97.6 +/- 2.6, 102.1 +/- 3.7, and 95.2 +/- 5.2 mmHg in young, adult, and senescent rats, respectively. The relationships between RPP and diuresis/natriuresis or fractional excretions of water and sodium were similar in young and adult rats. However, in senescent rats the pressure-diuretic and pressure-natriuretic responses were slightly shifted to the right, so that diuresis and natriuresis were significantly lower at higher levels of RPP. Glomerular filtration rate was well autoregulated, and there were no differences between young and adult rats at each level of RPP. However, a significantly lower glomerular filtration rate was observed in senescent rats. These results indicate an age-related decline in the pressure-dependent sodium and water excretion that appears to be due to a decrease in glomerular filtration and an increase in tubular sodium reabsorption.
Aging↗
Endogenous inhibitor of Na-K-Cl cotransport system in inbred Dahl rats.
Dahl salt-sensitive (DS) rats seem characterized by a ubiquitous increase in Na-K-Cl cotransport activity. Here, an endogenous inhibitor of the Na-K-Cl cotransport system (cotransport inhibitory factor, CIF) was investigated in inbred Dahl salt-sensitive (DS) and salt-resistant (DR) rats. The animals were orally loaded for 10 days with 2% NaCl. Plasma from salt-loaded DS rats inhibited cotransport with a 50% inhibition concentration value (IC50) of 6.4 +/- 0.6% (% plasma concentration, vol/vol) vs. 24.2 +/- 2.2% in DR rats (P < 0.0001). In urine, IC50 for cotransport inhibition was constantly lower in DS before and all during the whole salt-loading period (after 10 days of salt loading, IC50 was 2.59 +/- 0.11% and 6.00 +/- 0.24% in DS and DR rats, respectively; P < 0.0001). After 3 days of salt loading, higher salt appetite in DS rats magnified the differences in urinary CIF excretion. In erythrocytes from DS rats, increased cotransport activity was strongly correlated with urinary CIF excretion (r = 0.967). In conclusion, DS rats present increased plasmatic and urinary CIF levels. This can be a compensatory phenomenon to reduce cotransport hyperactivity and increased NaCl reabsorption at the thick ascending limb of Henle's loop.
Animals↗
Role of the renin-angiotensin system in the development of thyroxine-induced hypertension.
OBJECTIVE: We evaluated the influence of chronic blockade of the renin-angiotensin system on hypertension induced by long-term thyroxin (T4) administration. To this end, we determined the effects of chronic treatment with captopril on blood pressure, cardiac hypertrophy and other renal and metabolic variables of hypertensive hyperthyroid rats. METHODS: T4 was administered s.c. at 0.38 mumol/kg per day and captopril was given in the drinking water (1.38 mmol/l). Both treatments were maintained for 6 weeks. Control rats received tap water. After the treatment period, the rats were placed in metabolic cages. Later, blood pressure was measured in conscious rats by intra-arterial determination. RESULTS: T4-treated rats showed an increased mean arterial pressure (MAP) whereas, in rats treated with T4 plus captopril, MAP was similar to that of the control group. Captopril did not affect the increased heart rate or ventricular weight/body weight ratio of hyperthyroid rats, but it improved the reduced creatinine clearance of these animals. CONCLUSIONS: The elevation in blood pressure produced by long-term T4 administration was prevented by chronic blockade of the renin-angiotensin system. Captopril improved the renal function of hyperthyroid rats, but did not affect the relative cardiac hypertrophy of these animals.
Animals↗
Evidence of formation and participation of singlet oxygen in the in vitro phototoxicity of the combined diuretic triamterene and hydrochlorothiazide.
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Chromatography, Thin Layer↗
Usefulness of cryohemolysis test in the diagnosis of hereditary spherocytosis.
The clinical suspicion of hereditary spherocytosis (HS) must be confirmed at the clinical laboratory. The osmotic fragility test (OFT) and the autohemolysis test (AHT) are the worldwide accepted assays to establish a definite diagnosis of HS; however, they have some disadvantages. We describe herein our experience with the cryohemolysis test (CHT) as a tool to confirm the HS diagnosis. We included four groups of subjects, namely, patients with clinical HS, patients with mechanical heart valve prosthesis, malignant hematological diseases and healthy blood donors. CHT was carried out in all the groups, while OFT and AHT only in the HS patients and healthy individuals. OFT and AHT were performed according to previously described techniques. CHT was performed using red blood cells incubated in a hypertonic solution, preheated for 10 min and then transferred to an ice bath for an additional 10 min. The resulting cryohemolysis was determined measuring the free hemoglobin in the sample. There were no differences among the groups in terms of general characteristics. All HS suspicious patients had a positive OFT and AHT. CHT was positive in all patients from the HS group but in none of the subjects from the control groups (p < 0.001). We found that CHT is a faster and easier-to-perform assay compared with OFT and AHT. Moreover, using CHT, the zone between normal and abnormal results is wider than OFT or AHT. We propose 0.7 to 11% hemolysis as reference values for CHT.
Adult↗
[Improvement of expected and final height in girls with central precocious puberty treated with gonadotropin releasing hormone analogues].
BACKGROUND: To evaluate the effect of GnRH-analogue triptoreline on the predicted adult height and final height in central precocious puberty (CPP). PATIENTS AND METHODS: The study included 14 girls with CPP treated for 1-6 years with triptoreline depot (75 micrograms/kg/28 days/i.m.; group 1). The criteria for diagnosis included the following: compelling evidence of rapid progression of puberty, with a bone age (BA) greater than 2 SD above the mean value for chronological age (CA) associated with poor initial predicted final height and growth speed greater than 2 SD above the mean value for age. In addition we obtained data from 6 untreated girls with advanced puberty and good predicted adult height followed during the same period of time (group II). 7 of 14 girls of group I and 5 of 6 girls of group II attained final height. RESULTS: A decrease in growth speed and an increase and in CA/BA ratio were observed after three years of treatment (+4.9 +/- 0.7 SD to -1.45 +/- 2.63 SD and 0.62 +/- 0.14 to 0.74 +/- 0.09 respectively; P = 0.034; n = 6). The predicted adult height increased significantly after two years of treatment (153.1 +/- 4.49 to 156.94 +/- 5 cm; p = 0.041; n = 10) and was more evident after three years of treatment (153.84 +/- 5.77 to 160.7 +/- 7.5 cm; p = 0.03; n = 6). The final height of 7 girls of group I who attained it was similar to target height (161 +/- 3.1 vs. 159 +/- 1.3 cm; NS) and greater than initial predicted adult height (161 +/- 3.1 vs. 154 +/- 2.1 cm; p = 0.044) and than final height of the 5 girls of group II (161 +/- 3.1 vs. 154.28 +/- 6.1 cm). CONCLUSIONS: Triptorelin depot improves predicted adult height and final height of girls with early central puberty may be over their target height.
Body Height↗
Advantages of using a cell separator and metrizamide gradients for human islet purification.
Human islet transplantation has a high rate of failure, often due to primary nonfunction, which suggests that islets are damaged during the processing of the pancreas. The preparation of human islets for transplantation is still a complex process that requires large teams of surgical and laboratory personnel. To overcome this problem, we have adopted the use of the IBM 2991 COBE cell separator and a metrizamide/Ficoll density medium that is easy to prepare. Twenty-seven pancreatic glands have been processed using the COBE cell separator, 23 of which were purified in metrizamide/Ficoll gradients and 4 in bovine serum albumin gradients. The results show an improvement of recovery and viability in these preparations when compared retrospectively with manual gradients. More importantly, the time required for purification was shortened to one fourth the usual time and total processing time is about half as long. Moreover, a team of two laboratory staff was regularly able to prepare islets for transplantation, reducing the separation time from 7 hr to 3.5 hr. We conclude that the automatic cell separator and metrizamide-based separation medium are useful modifications of current islet purification methods.
Adolescent↗
Characterization and inhibition of a cholecystokinin-inactivating serine peptidase.
A cholecystokinin (CCK)-inactivating peptidase was purified and identified as a membrane-bound isoform of tripeptidyl peptidase II (EC 3.4.14.10), a cytosolic subtilisin-like peptidase of previously unknown functions. The peptidase was found in neurons responding to cholecystokinin, as well as in non-neuronal cells. Butabindide, a potent and specific inhibitor, was designed and shown to protect endogenous cholecystokinin from inactivation and to display pro-satiating effects mediated by the CCKA receptor.
Amino Acid Sequence↗
Renal vascular reactivity to ATP in hyper- and hypothyroid rats.
The effects of adenosine triphosphate (ATP) on the renal vasculature of isolated kidneys from control, hyper- and hypothyroid rats were characterized. ATP responsiveness was evaluated in basal tone and in raised tone (phenylephrine 10(-6) M) preparations. These responses were compared with those obtained with barium chloride or sodium nitroprusside (SNP), used respectively as nonreceptor agonist for vasoconstriction or vasodilation. In preparations at basal tone, ATP produced dose-related vasoconstriction, which was increased in hyperthyroid kidneys, and was severely attenuated in kidneys from hypothyroid rats. In raised tone preparations from control rats ATP produced a dual response: vasoconstriction at low doses, which declined with increasing doses to give way to vasodilator responses; biphasic responses were found in some kidneys. Hyperthyroid kidneys showed increased pressor responses and a vasodilator response similar to those seen in kidneys from control rats. However, in hypothyroid kidneys the vasodilator response was abolished. The responses to barium chloride and to SNP were significantly increased and decreased in hyper- and hypothyroid kidneys, respectively; vasoconstrictor responses to SNP were also found in hypothyroid kidneys. Hence the abnormal responses to ATP observed in both thyroid dysfunctions may be partially explained by unspecific alterations in the contractile machinery of the renal vasculature in these kidneys. However, ATP responsiveness (vasoconstriction at low tone and vasodilation at raised tone) was more severly affected in hypothyroid kidneys, suggesting that purinergic (P2X and P2Y) receptor activity may be decreased in these organs.
Adenosine Triphosphate↗
Trypanosoma cruzi: study of the distribution of two widespread clonal genotypes in Bolivian Triatoma infestans vectors shows a high frequency of mixed infections.
The detection of two widespread Trypanosoma cruzi clonal genotypes (20 and 39) in feces of Bolivian specimens of the vector Triatoma infestans was performed by a combination of polymerase chain reaction and clone-specific DNA hybridization. The hybridization pattern of 186 PCR positive samples cf T. infestans feces collected in two Bolivian departments identified clone 20 in 74.2% and clone 39 in 63.4% of the triatomine bugs. For the first time, a high percentage (mean: 43.2 +/- 26%) of mixed infections (presence of both clones in a given fecal sample) in various localities was recorded. Results were in agreement with the two assumptions of independent transmission of clones 20 and 39 and of the absence of selection in the natural cycles under survey. Statistical analysis of the geographical distribution of clones 20 and 39 favored the hypotheses that the frequencies of T. cruzi natural clones are different among localities and that these differences are not proportional to the distances that separate the localities. The epidemiological significance of these results is discussed.
Animals↗
A radioimmunoassay for the tripeptide Gly-Trp-Met, a major metabolite of endogenous cholecystokinin in brain.
We developed a specific and sensitive radioimmunoassay for the tripeptide Gly-Trp-Met (GWM) after its derivatization with p-benzoquinone. Measurable amounts of endogenous GWM-like immunoreactivity (GWM-ir), coeluting in HPLC with authentic GMW were detected in the medium of depolarized slices of rat cerebral cortex. The tripeptide GWM appears as the major inactive CCK-8 metabolite since a major fraction of CCK-8-ir released from the slices was apparently recovered in the medium as GWM. In addition, in the presence of the serine reagent diisopropylfluorophosphate, a strong decrease of GWM formation was observed to accompany the corresponding increase of CCK-8-ir recovery in medium. The present study confirms that (a) serine peptidase(s) is(are) responsible for inactivating endogenous CCK-8 in brain as previously proposed (Rose et al. Proc Natl Acad Sci USA 1988; 85:8326).
Amino Acid Sequence↗
Vascular reactivity and flow-pressure curve in isolated kidneys from rats with N-nitro-L-arginine methyl ester-induced hypertension.
OBJECTIVES: The purpose of this study was to determine the contribution of the functional changes in resistance vessels to the hypertension induced by chronic nitric oxide synthase inhibition in rats. Another goal of this study was to evaluate whether this model of hypertension is accompanied by changes in the activity of endothelium-derived hyperpolarizing factor (EDHF). METHODS: Hypertension was induced by long-term (6 weeks) oral administration of N-nitro-L-arginine methyl ester (L-NAME; 75 mg/100 ml in the drinking fluid). Vascular reactivity to vasoconstrictors (phenylephrine and barium chloride) and vasodilators (acetylcholine and nitroprusside) and the flow-pressure curve were examined in isolated perfused kidneys preparations. Vascular reactivity to vasoconstrictors and the flow-pressure curve were studied under basal conditions or after the infusion of L-arginine (100 mumol/l). The activity of EDHF was evaluated by comparing the dose-response curves for acetylcholine obtained in potassium chloride- and phenylephrine-preconstricted preparations. RESULTS: Kidneys from L-NAME-induced hypertensive rats showed increased sensitivity to vasoconstrictors with a greater duration of the pressor responses at high doses and markedly up-shifted flow-pressure curve in comparison with that obtained in control kidneys. These differences disappeared when the kidneys from control and L-NAME-treated rats were infused with L-arginine. The kidneys from L-NAME-treated rats also showed a decreased responsiveness to acetylcholine with an augmented reactivity to nitroprusside. The acetylcholine dose-response curve was reduced in control preparations and greatly attenuated in L-NAME-treated preparations when the renal vasculature was preconstricted with potassium chloride. CONCLUSIONS: The changes in vascular reactivity observed in L-NAME-induced hypertensive rats may play an important role in the pathogenesis of this type of hypertension. Moreover, it is also suggested that long-term nitric oxide inhibition may be associated with increased activity of EDHF.
Acetylcholine↗