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Biomedical subjects

J Alonso

Publications and source records attributed to J Alonso.

At least 253 records · Page 14Linked to original sources
PubMed1989

[Effect of progesterone and estradiol on the regulation of pulsatile secretion of LH in the various phases of the estrous cycle of rats].

The normal changes on LH pulse amplitude and frequency throughout the estrous cycle and the specific role of Progesterone (P) and Estradiol (E) on pulsatile LH release have been determined in rats at the different stages of the estrous cycle. The effects on pulsatile LH release 24 h after ovariectomy (OVX), have been studied, as well as the way the normal values of the pulsatile release was re-established, when the physiological levels of P and/or E were restored by implantation of either P, E, or both Silastic capsules in OVX rats 24 h early. Our data during the rat estrous cycle, have confirmed that the lowest pulsatile LH release was on estrus, and the largest LH pulses were obtained on diestrus day 1, when the plasmatic levels of both P and E were lowest. Moreover, a variable ovarian steroid effect has been found at the different stages of the cycle. In estrus and diestrus day 2, both steroids were necessary to restore the normal values of the pulsatile LH release in OVX rats 24 h before, while in proestrus, the main steroid was Estradiol, although a non steroidal ovarian factor was also necessary to restore the normal pulse amplitude. Finally, in diestrus day 1 there was an absence of an ovarian steroid negative feedback on pulsatile LH release, because the levels of both steroids were too low in this stage, to exert a regulatory role on pulsatile LH release.

Animals↗
PubMed1989

External fixation of femoral fractures. Indications and limitations.

The role of external fixation in the management of femoral shaft fractures is reviewed based on a study of 24 femoral fractures managed by either an AO or a Wagner external fixator during 1983-1986. Indications included open fractures with soft-tissue injury (13 patients), comminuted shaft fractures (six patients), and unstable operative candidates (five patients). In 14 patients, external fixation was a temporary method (Group I), while in ten patients it was the definitive method of stabilization (Group II). Twenty-one patients achieved solid union, two developed a delayed union, and one had a nonunion. Three patients developed pin-tract infections, and one developed osteomyelitis after intramedullary fixation in Group I. Two patients in Group II developed shortening (2.1 cm and 3.2 cm). Loss of motion occurred in 11 patients, averaging 56 degrees. It is suggested that external fixation be considered in the following types of femoral fractures: open fractures for aggressive management of soft-tissue injuries; closed fractures in severely traumatized, burn, or head injury patients; fractures about the knee resulting in floating knees; and infected femoral nonunions and pseudarthroses.

Adolescent↗
PubMed1988

Chloride determination in serum by a flow-injection analysis precipitation pseudo-titration technique using a flow-through all-solid-state silver electrode.

A simply constructed, tubular, all-solid-state, flow-through silver electrode for flow-injection analysis (F.I.A.) is described. Use of a single line manifold accommodating the silver electrode, with a low level of silver ion (5 x 10(-4) M) in the carrier stream, is a useful method to determine chloride in serum, by means of a precipitation pseudo-titration F.I.A. technique. The sampling frequency is about 60/h.

Journal Article↗
PubMed1988

Long-term results of conservative repair of rheumatic aortic valve insufficiency.

From July 1974 to January 1986, 50 patients underwent conservative repair for rheumatic aortic valvular disease at our institution. Eleven were male and 39 female, with an average age of 39.5 years (range 17-57). The aortic lesion was associated in all cases with a predominant mitral lesion. Twenty-five also had tricuspid disease which was surgically treated in 17. Twenty-six had aortic regurgitation and 24, a mixed lesion. The surgical techniques used were: (1) commissurotomy, (2) annuloplasty, (3) cusp free edge unfolding and (4) supra-aortic crest enhancement. Two patients had one cusp extended with pericardium. There were 3 hospital deaths (6%). Six patients were lost to follow-up at different periods. Maximum follow-up was 12.58 years with a mean of 7.78 years per patient. Twelve required reoperation with 3 deaths. Three reoperations were due to failure of the mitral bioprosthesis without reoperation on the aortic valve. Of the remaining 9 patients who had aortic and mitral dysfunction, 4 had severe aortic insufficiency. The actuarial freedom from reoperation at 13 years was 75% and the overall actuarial survival was 86%. It is concluded that these surgical techniques can be applied successfully in moderate rheumatic aortic valve disease accompanying a predominant mitral lesion. This is particularly relevant when a mitral reconstruction has been performed.

Adolescent↗
PubMed1988

Influence of tachycardia and arterial hypertension on infarct size in the pig.

To investigate the clinically important but controversial question of how hypertension during coronary occlusion affects infarct size 24 pigs underwent 1 h occlusion of the mid left anterior descending coronary artery and 24 h reperfusion and were randomised to one of three treatment groups. In group 1 blood pressure was increased during the occlusion period by an infusion of methoxamine; in group 2 tachycardia was induced by atrial pacing; and in group 3 no intervention was performed. The area at risk and infarct size were quantified by digital planimetry of slices of myocardium previously marked with fluorescein and with triphenyl-tetrazolium. Methoxamine maintained mean aortic blood pressure at 117 (SEM8) mmHg during occlusion, whereas the values were 80(6) mmHg in group 2 and 67(9) mmHg in group 3. Pacing increased heart rate to 146(1) beats.min-1 in group 2; it was 103(5) in group 1 and 99(8) in group 3. The pressure-rate product achieved was similar in groups 1 and 2 and significantly higher than in group 3. The pathological studies showed infarct size to be moderately but significantly larger in group 1 (14[3.5]% of the left ventricle) and similar in groups 2 (10.5[3.9]%) and 3 (10.1[2.2]%). The ratio of infarct size to area at risk was also significantly higher (0.743[0.057]) in group 1 with no differences between group 2 (0.604[0.055]) and group 3 (0.613[0.027]). At similar pressure-rate product, infarct size was thus greater with hypertension but not with pacing alone, showing a deleterious effect of increasing blood pressure in this experimental model with negligible collateral blood flow.

Animals↗
PubMed1988

Open reduction and internal fixation of volar lip fractures of the distal radius.

Fractures of the volar lip of the distal radius are relatively uncommon injuries. However, controversy exists concerning the treatment of these fractures. We reviewed our experience with open reduction and internal fixation through a volar approach using buttress plates. Sixteen patients with 17 fractures were treated by this method. Their ages ranged from 16 to 65 years (average 38 years). Eight fractures occurred secondary to motor vehicle accidents, while the remaining patients sustained falls. Mean follow-up time was 19.5 months. All fractures healed with no infections. Sixteen of the fractures were treated primarily with open reduction and internal fixation, while one patient was treated 6 weeks after injury for a malunion. Ranges of motion averaged 71 degrees dorsiflexion, 60 degrees palmar flexion, 79 degrees pronation, 78 degrees supination, 22 degrees radial deviation, and 32 degrees ulnar deviation. Analysis of results demonstrated 12 excellent, 2 good, and 3 fair results. Two patients with fair results had nonanatomic restoration of the joint surface at surgery, while the other patient with a fair result was treated late. We recommend early open reduction and internal fixation of displaced or unstable volar lip fractures of the distal radius. Accurate anatomic alignment and stable fixation are achieved with the volar buttress plate. Motion can begin 2-3 days after surgery to aid in obtaining excellent functional results.

Adult↗
PubMed1988

H-n.m.r. studies on the specificity of the interaction between bovine pancreatic ribonuclease A and dideoxynucleoside monophosphates.

The titration curves of the C-2 histidine protons of bovine pancreatic ribonuclease A in the presence of several dideoxynucleoside monophosphates (dNpdN) were studied by means of proton nuclear magnetic resonance at 270 MHz in order to obtain information on the ligand--RNase A interaction. The changes in the chemical shift and pKs of the C-2 proton resonances of His-12, -48, -119 in the complexes RNase A--dNpdN were smaller than those previously found when the enzyme interacted with mononucleotides. The pK2 of His-12 was not affected by the interaction of the enzyme with these ligands, whereas, the perturbation of the pK2 of His-119 was clearly dependent on the nature of the ligand. If there is a pyrimidine nucleoside at the 3' side of the dideoxynucleoside monophosphates, as in TpdA and TpT, an enhancement due to the well known interaction of the phosphate in p1, the catalytic site, was found. However, when there is a purine nucleoside, as in dApT and dApdA, a decrease in the pK2 value was observed and we propose that in such cases the phosphate group interacts in a secondary phosphate binding site, p2. The results obtained suggest the existence of different specific interactions depending on the structure of the dideoxynucleoside monophosphate studied.

Deoxyribonucleotides↗
PubMed1988

[Idiopathic form of late hemorrhagic disease caused by a deficiency of vitamin K. A presentation of 3 cases].

Three one month old infants with idiopathic late haemorrhagic disease due to vitamin K deficiency are reported. Patients had been exclusively breast fed and had not received vitamin K at birth. Initial symptomatology was typical in the three cases. Two of them had an intracranial haemorrhage with exitus in one of them. Coagulation study showed non measurable levels of PT and PTT and a significant reduction in vitamin K dependent factors. Coagulopathy was corrected with parenteral administration of vitamin K and fresh plasma. Pathogenic factors of this entity are reviewed and present day recommendations to prevent occurrence of this problem are discussed.

Female↗
PubMed1987

External fixation of open comminuted fractures of the proximal phalanx.

External fixation is an accepted method of treatment for many injuries, however, only a limited number of reports concern its use in open, comminuted fractures of the hand. Ten patients with eleven fractures of the proximal phalanx were treated using the AO/ASIF small external fixator. Five fractures involved the interphalangeal joint (IPJ), two the metacarpophalangeal joint (MPJ), and four the shaft. Nine fractures were caused by small caliber gunshot wounds, one was due to a power saw injury, and one occurred during a three wheeler accident. The patients with interphalangeal joint involvement all had extensive involvement of one or both of the joint surfaces. The fixator was placed across the joint and a stable ankylosis allowed to occur with the IPJ in 30 degrees to 40 degrees of flexion. MPJ motion averaged 75 degrees in these patients while distal interphalangeal joint (DIPJ) motion averaged 20 degrees. The four patients with shaft fractures all healed, but three required bone grafting. These patients averaged 85 degrees of MPJ motion, 25 degrees of proximal interphalangeal joint (PIPJ) motion, and 30 degrees of DIPJ motion. One patient with metacarpophalangeal joint involvement regained 85 degrees of MPJ motion but had limited motion at the PIPJ and DIPJ. The other patient with MPJ involvement suffered massive bone loss; a ray amputation was eventually performed. Complications included pin tract drainage in three of the eleven fractures and slight loss of reduction in two fractures. The best clinical results occurred when the fixator was used as a digit salvage procedure in interphalangeal joint fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Complete acromioclavicular separations. A comparison of operative methods.

A retrospective study of the surgical treatment methods for complete acromioclavicular (AC) dislocations was initiated to investigate the efficacy of each. During the years 1972-1985, a total of 95 surgical procedures were performed for complete AC dislocations. The medical records of 90 cases were available for review. The operative methods compared coracoclavicular (CC) with AC fixation methods. Excision of the distal clavicle was performed for chronic dislocations. AC fixation methods included Kirschner wires alone, Kirschner-wire fixation with coracoacromial ligament transfer, and Kirschner-wire fixation with tension wiring. Results were graded using evaluation of pain, range of motion, and residual deformity. AC fixation methods proved to be more successful than CC fixation methods. Excellent results were obtained in more than 89% of both AC and CC methods. AC methods had more minor complications including infections and implant breakage, but no failure or recurrences of the dislocation. CC methods resulted in 9% failure or recurrences. Of the AC fixation methods, the Kirschner wire with tension wiring gave the best results but required a more extensive operation for removal of implants. Excision of the distal end of the clavicle is an adequate form of treatment for the chronic complete painful AC dislocation.

Acromioclavicular Joint↗
PubMed1986

Modification of bovine pancreatic ribonuclease A with 6-chloropurine riboside.

The chemical modification of bovine pancreatic ribonuclease A by 6-chloropurine riboside was studied to obtain information about the role of the purine nucleoside moiety of the ribonucleic acid in the enzyme-substrate interaction. The residues involved in the reaction were identified, after performic acid oxidation and trypsin digestion, by reverse-phase HPLC peptide mapping. The labeled peptides were detected by following the absorbance at 254 nm, and amino acid analyses of these peptides showed that the reaction had taken place with the amino groups of Lys-1, -37, -41, and -91. The specificity of the reaction was unaffected by changing the ligand:protein molar ratio. Partial separation of the reaction products was accomplished by means of chromatography on CM-Sepharose: four labeled fractions corresponding to mono- and bisubstituted derivatives were found. One of the monosubstituted fractions (fraction E) contained a homogeneous protein with the nucleoside bound to the alpha-amino group of Lys-1 whereas the other (fraction D) was a mixture of derivatives labeled in the epsilon-amino group of Lys-1, -37, -41, and -91. Kinetic studies of these two monosubstituted fractions were performed with cytidine 2',3'-phosphate and ribonucleic acid as substrates. These derivatives showed a noncompetitive inhibition-like behavior with respect to RNase A. Results support the existence of several RNase A regions with affinity for purine nucleosides.

Animals↗
PubMed1985

Immunohistochemical findings in acute atherosis associated with intrauterine growth retardation.

Lesions of acute atherosis in 23 placentas from pregnancies complicated by fetal growth retardation (less than tenth percentile) were studied by an immunoperoxidase staining. Twelve of them were from normotensive pregnancies, ten complicated by pregnancy induced hypertension, and the remaining associated with systemic lupus erythematosus. Twenty-three placentas with physiological changes of the spiral arteries corresponding to normal pregnancies served as controls. Six of the cases complicated by fetal growth retardation showed absence of physiological changes in basal decidua. Massive intramural granular deposits of IgM, a smaller amount of C3 and C1q, and slight deposits of IgA and IgG were found in vessels with acute atherosis. No intramural deposition of immunoglobulins or complement was observed in vessels with or without physiological changes. The presence of granular deposits of immunoglobulins and complement within the vessel walls with acute atherosis may be related to an immunological disorder, probably mediated by immune complexes.

Acute Disease↗
PubMed1985

Subtalar dislocations: a prognosticating classification.

A review of the literature and analysis of eight cases of subtalar dislocations was undertaken to correlate our experience with others and to determine a classification for prognostication. Our findings corresponded with those found by others. A 75% incidence of associated injuries was present in our series and these represented a continuum of varying degrees of complication. A new system was devised whereby increasing severity of associated injuries correlated with increasing rate of complications, including loss of motion, arthritis, pain and avascular necrosis. Dislocations were classified according to: no associated injuries, those with soft tissue injuries, extra-articular fractures, intra-articular fractures and those prone to development of avascular necrosis, ie, open dislocations and fractures of the body of the talus. It was found that associated fractures increased the immobilization period as well as the incidence of complications. Intra-articular fractures have demonstrated increased rates of arthroses in the subtalar joint. Avascular necrosis, an infrequent but devastating complication, is primarily associated with open dislocations and dislocations with concomitant fractures of the body of the talus. Our series had two open subtalar dislocations, neither of which developed avascular necrosis.

Adolescent↗
PubMed1983

Affinity chromatography study of the interaction of ribonucleotides with bovine pancreatic ribonuclease covalently bound to Sepharose 4B.

The preparation of immobilized bovine pancreatic ribonuclease by covalent attachment to Sepharose 4B, with and without a spacer arm, is described. The coupling reaction was carried out at two different pH values, 8.5 and 10.5, and the different kinetic properties shown by the resulting preparations probably reflect the influence of the particular amino acid side-chains involved in the covalent coupling of the enzyme to the insoluble matrix. The strength of binding of mononucleotides, at 4 degrees C, as deduced from the salt concentration at which they are eluted from an immobilized RNAase column, follows the order 5'-GMP greater than 5'-AMP greater than 3'-UMP greater than 3'-CMP. When binary mixtures of a 3'-pyrimidine nucleotide and a 5'-purine nucleotide are chromatographed jointly, a co-operative effect is found and the elution of either or both ligands is retarded. This behaviour can be explained in terms of the preferential binding of each kind of nucleotide to different sub-sites in the enzyme. The stoichiometry and association constant for 3'-CMP and 5'-AMP at pH 7.0 were also determined.

Animals↗