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Biomedical subjects

A Mendoza

Publications and source records attributed to A Mendoza.

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

Cervical flexion: its contribution to normal and abnormal cardiac morphogenesis.

Although His in 1881 and Patten in 1922 suggested that cervical flexion could play an important role in normal cardiac morphogenesis, until recently this hypothesis has been largely neglected. The purpose of this report is to present data indicating that prevention of cervical flexion leads to double outlet right ventricle (DORV), which is unrelated to any affect on neural crest cell migration. At stage 11-12, suture material was inserted into the neural tube to prevent cervical flexion. Six out of 22 experimental embryos survived until stage 38 and 5 out of 6 had DORV. Neither abnormalities of the aortico-pulmonary septum nor interruption of the aortic arch were observed at dissection. Hemodynamic studies performed at stage 18 revealed distinctive characteristics that are inconsistent with hemodynamic studies previously reported following neural crest ablation. With respect to immunohistochemical studies using neural crest associated antigen HNK-1 antibody, normal migration of neural crest cells was noted in the outflow tract in the experimental embryos at stage 22. These hemodynamic and immunohistochemical studies suggest that insertion of suture material into the neural tube at stage 11-12 does not jeopardize neural crest migration. We propose that reduction in cervical flexion increases the distance between the future aorta and the left ventricle, which prevents the transition of intracardiac flow pattern from a serial circulation to a parallel one, leaving persistence of a "double outlet" from the right ventricle.

Animals↗
PubMed1996

Clinical spectrum, investigations and treatment of Budd-Chiari syndrome.

The clinical presentation, investigations, therapeutic modalities, prognosis and outcome of 44 patients with Budd-Chiari syndrome (BCS) were reviewed. There were 27 women and 17 men. Median age at presentation was 37 years (range 14-60). Possible aetiological factors were identified in 31 patients (70%). Myeloproliferative disorders were the commonest aetiology. Abdominal pain and swelling were the commonest presenting symptoms. Sixteen patients underwent a shunt operation (14 mesocaval, 2 mesoatrial). Ten patients had liver transplantation. Eleven patients had angioplasty/stent as their only treatment, and seven were treated medically or died before any treatment was instituted. Radiological intervention was comparable to mesocaval shunt in relieving patients' symptoms and in achieving good long-term results. Medical treatment and liver transplantation both yielded poor results. Radiological intervention in the form of balloon angioplasty or stent placement gives good results in a subgroup of BCS patients, and should be tried first to relieve the hepatic outflow obstruction. Mesocaval shunts provide good results in selected cases. Underlying haematological causes should be intensively investigated and promptly treated.

Adult↗
PubMed1996

Placental cord insertion visualization with prenatal ultrasonography.

Color Doppler and gray scale sonography can be used prenatally to identify the location of the cord insertion into the placenta. The purposes of this paper were to (1) relate sonographic identification of placental cord insertion with placental pathology; (2) evaluate the possibility that a marginal cord insertion may evolve into a velamentous cord insertion; and (3) determine the frequency and factors affecting sonographic visualization of cord insertion. Our results show that the sonographic assessment of cord insertion correlated with the pathologic outcome in 83% (106 of 128) of singleton pregnancies and at least one of the fetuses in 72% (8 of 11) of twin or triplet pregnancies. Although the sensitivity for identification of an abnormal cord insertion was low (42%), the specificity was high (95%). Our data suggest that marginal cord insertion evolved into velamentous cord insertion in one singleton and one twin. Our results showed that cord insertion was visualized in 54% of fetuses scanned in a routine clinical practice. Cord insertion visualization was possible at all gestational ages, although it was more difficult at later gestational ages. In conclusion, this study provides evidence that (1) ultrasonography (either gray scale or color Doppler) is useful in identifying normal, marginal, and velamentous cord insertion; (2) marginal cord insertion may evolve into velamentous cord insertion as pregnancy progresses; (3) in clinical practice the cord insertion site was visualized in just over half of the cases, and (4) prenatal identification of marginal and velamentous cord insertion potentially may be useful for planning obstetrical management.

Female↗
PubMed1995

Prenatal sonographic diagnosis of intracranial haemorrhage: report of a case with a sinusoidal fetal heart rate tracing, and review of the literature.

The sinusoidal fetal heart rate pattern has been described in association with severe fetal anaemia, with fetal hypoxaemia, and with the administration of parenteral narcotics. Here, we report a case of decreased fetal movement in which a sinusoidal tracing was recorded. The sonographic diagnosis of a massive fetal intracranial haemorrhage was made. A non-interventive approach was taken and the fetus died soon after in utero. We review 28 previous cases in which the prenatal sonographic diagnosis of fetal intracranial haemorrhage was made, including the underlying maternal and fetal factors and neonatal outcomes. We propose that the sinusoidal tracing in this case was due to the intracranial bleed and suggest that fetal intracranial haemorrhage be considered in the sonographic evaluation of the fetus with a sinusoidal pattern.

Cerebral Hemorrhage↗
PubMed1995

Monoamniotic and pseudomonoamniotic twins: sonographic diagnosis, detection of cord entanglement, and obstetric management.

OBJECTIVE: To assess accuracy of detecting cord entanglement in monoamniotic twins, and to describe perinatal outcomes with aggressive obstetric management. METHODS: Seven nonconjoined monoamniotic twin pregnancies and one pseudomonoamniotic twin pregnancy were diagnosed sonographically and evaluated with serial scans and cardiotocography. In the absence of other indications, patients were delivered by elective cesarean on demonstration of lung maturity at or beyond 32 weeks' gestation. RESULTS: Cord entanglement was diagnosed correctly in four pregnancies, missed in one, and excluded correctly in three. Four pregnancies were delivered after demonstration of pulmonary maturity, three because of premature rupture of membranes or uncontrollable preterm labor, and one because of fetal heart rate abnormality during tocolysis for preterm labor. The mean gestational age at delivery was 33.2 +/- 1.6 weeks, with birth weight 2011 +/- 262 g; all neonates were live-born. Newborn stays averaged 12.0 +/- 5.8 days for the eight neonates delivered electively. CONCLUSION: Monoamniotic twin pregnancies and cord entanglement in such twins were diagnosed reliably by ultrasound. Abnormal tracings prompting cesarean delivery occurred in two of the five pregnancies with cord entanglement. Amniocentesis reflected pulmonary maturity of both twins in all pregnancies so assessed, and delivery after 32 weeks' gestation, with lung maturity, resulted in good perinatal outcomes. Statistical validity of these findings is limited by our small sample size.

Amnion↗
PubMed1995

Hereditary haemorrhagic telangiectasia and secondary biliary cirrhosis.

We report the case of a 65-year-old woman with a 10-year history of biliary disease and a 3-year history of anaemia, lethargy, angina and recurrent ascending cholangitis; she had hereditary haemorrhagic telangiectasia (HHT) with aneurysms in the splanchnic circulation, and was assumed to have secondary biliary cirrhosis with portal hypertension and hypertrophic obstructive cardiomyopathy. Her portal hypertension was caused by secondary biliary cirrhosis induced by intrahepatic gallstones; this was associated with left ventricular hypertrophy and a high cardiac output, caused by increased splanchnic circulation, and with aneurysms in the superior mesenteric and pancreaticoduodenal arteries, which were visualized by angiography. We conclude that HHT can produce abnormal abdominal vascular anatomy, which affects haemodynamic performance and makes it difficult to manage a patient with portal hypertension caused by secondary biliary cirrhosis. HHT has been shown to be associated with intrahepatic biliary stones and might have a causal role. When assessing patients with this type of condition for liver transplantation, particular attention should be paid to haemodynamic and circulatory abnormalities.

Aged↗
PubMed1994

Early sonographic diagnosis of intrapericardial teratoma.

An intrapericardial teratoma associated with a large pleural effusion and elevated aortic outflow velocity was diagnosed at 23.6 weeks' gestation. Less than 4 weeks earlier, an obstetric scan, including a four-chamber heart view, had been normal. In less than a week following diagnosis, fetal hydrops and bradycardia developed. 'Heroic' pericardiocentesis was declined by the patient, and the fetus died. This case demonstrates the potential for rapid growth in pericardial teratomas, and illustrates the possibility of anticipating fetal compromise from tumor mass effect, when intracardiac Doppler studies are abnormal. Implications for management of these rare tumors, and specifically for the hypothetical role of fetal surgery, are discussed.

Journal Article↗
PubMed1994

Overwhelming maternal sepsis due to a gas-forming Escherichia coli chorioamnionitis.

We report a case of a patient who developed fulminant sepsis and respiratory distress caused by a gas-forming Escherichia coli intrauterine infection following premature rupture of the membranes and fetal death. Such gas-forming infections are rare, and, when they occur, they are usually caused by Clostridium welchii. This patient was treated with antibiotics, ventilator support, and hysterectomy, and at follow-up was in good health.

Adult↗
PubMed1994

Accidental transmission of Creutzfeldt-Jakob disease by dural cadaveric grafts.

Four patients who received dural grafts of cadaveric origin in the course of posterior fossa procedures subsequently developed Creutzfeldt-Jakob disease (CJD). The interval from dural placement to clinical onset of CJD ranged from 16 months to nine years. Initial clinical presentation consisted of cerebellar symptoms, with dementia and myoclonus developing in later stages of the disease. EEGs showed diffuse slowing that evolved to a periodic activity pattern. CT and MRI were unremarkable in the early stages but pronounced cerebral and cerebellar atrophy with widened sulci and collections of fluid over the convexities were seen in the late stages of disease. The diagnosis was histologically proved by brain biopsy in all four cases. Molecular genetic analysis showed that the four patients were homozygous for methionine at codon 129 of the PrP gene. From this experience, and from six previous descriptions of this occurrence in the literature, it is manifest that awareness of the means of iatrogenic transmission of CJD, and the adoption of preventive measures, constitute the only effective way to stop the spread of CJD among patients who have neurosurgery.

Adolescent↗
PubMed1993

Prenatal diagnosis of a giant intracranial teratoma associated with pulmonary hypoplasia.

We present a case in which an intracranial tumour replacing all intracranial contents was diagnosed by sonography at 31 weeks' gestation. The patient was delivered by caesarean section and died shortly after delivery. At necropsy, the tumour was found to be a teratoma with no recognisable normal brain tissue present. Additional findings at necropsy included pulmonary and adrenal hypoplasia. The diagnosis and prognosis of intracranial teratomas diagnosed in utero, and the association of this tumour with pulmonary hypoplasia, are discussed.

Abnormalities, Multiple↗
PubMed1992

Early prenatal diagnosis of type II cystic adenomatoid malformation of the lung: sonographic and histological findings.

Cystic adenomatoid malformation is a rare abnormality of the fetal lung. Depending on the size and histology of the cyst, it is classified as type I, II or III. With improving ultrasound technology, prenatal diagnosis during the mid-trimester is now possible; however, the earliest previous reports of type II cases have been at 23-24 weeks' gestation. We here report cases diagnosed at 19.5 and 20.5 weeks. In contrast to the appearance of multiple small cysts seen later in pregnancy, these cases showed a predominance of marked hyperechogenicity, usually associated with type III malformations, with small areas of lung involved by sonographically detectable cysts. Both families chose pregnancy termination. Sonographic findings, counselling, and histology are presented and discussed.

Journal Article↗
PubMed1992

Colocalization of thrombospondin and syndecan during murine development.

Thrombospondin is an adhesive glycoprotein that is thought to play a role in tissue genesis and repair. We have used a monoclonal anti-thrombospondin antibody, designated 5G11, to localize thrombospondin in paraformaldehyde fixed, paraffin-embedded sections of developing mouse embryos. Thrombospondin expression is observed in uterine smooth muscle, endometrial glands, the decidua, and trophoblastic giant cells during the initial phase of post-implantation development in the embryo. Cardiac myocytes and neuroepithelial cells show positive staining for thrombospondin at day 8.5 of gestation, and this expression continues throughout the development of the myocardium and central nervous system. Strong staining for thrombospondin is seen in developing bone and in the liver. Thrombospondin is also observed in developing smooth muscle and skeletal muscle, as well as in a variety of epithelia, including the epidermis, small intestinal epithelium, lens epithelium, renal tubular epithelium, and the epithelium of the developing tooth. Comparison of thrombospondin staining with that of two known cell surface receptors for thrombospondin, syndecan and the vitronectin receptor, reveals remarkable colocalization of thrombospondin and syndecan in all tissues, but almost no coexpression with the vitronectin receptor. Coexpression of thrombospondin and syndecan may play an important role in cell-cell or cell-matrix interactions during development.

Animals↗
PubMed1992

Effect of ACE inhibition on the fetal kidney: decreased renal blood flow.

The kidneys of nine fetuses whose mothers were chronically hypertensive were examined microscopically. Three of these mothers used antihypertensive agents throughout pregnancy including one who used an angiotensin-converting enzyme (ACE) inhibitor. The tubular defects found in these kidneys were compared to the kidneys of 20 normal controls, 13 fetuses with various multiple malformation syndromes and six cases of the twin to twin transfusion syndrome. Evidence from these cases as well as the literature suggest that the primary mechanism by which ACE inhibitors affect development of the fetal kidney is through decreased renal blood flow.

Abnormalities, Drug-Induced↗
PubMed1991

Combined inguinal herniorrhaphy and transurethral prostatectomy.

Between January 1979 and June 1988, 41 men underwent combined inguinal herniorrhaphy and transurethral prostatectomy at the Instituto Nacional de la Nutrición in México. These cases (group 1) were compared retrospectively with 100 consecutive cases of inguinal herniorrhaphy alone (group 2) and 100 consecutive cases of transurethral prostatectomy alone (group 3) during the same period. Group 1 had the highest incidence of preoperative risk factors because of age and associated medical problems. However, there were no significant differences in the rate of operative or postoperative complications between groups. No recurrences of inguinal hernia were recorded in group 1 after a follow-up period of 47.1 months. The length of hospitalization was similar between groups, and no patient died. Our observations suggest that when an inguinal hernia and symptomatic prostatism occur together, combined inguinal herniorrhaphy and transurethral prostatectomy is a practical, safe and effective operative procedure. The advantages of this combined procedure include one anaesthetic period, one operative procedure, one hospital stay and one convalescence with morbidity and mortality rates that are comparable to those of inguinal herniorrhaphy or transurethral prostatectomy alone.

Age Factors↗
PubMed1988

Prenatal diagnostic options in cystic fibrosis.

There are currently two diagnostic options in cystic fibrosis. These involve assays for certain microvillar enzyme activities in amniotic fluid and recombinant deoxyribonucleic acid studies of markers linked to the cystic fibrosis gene on chromosome 7. The former are reduced in cystic fibrosis homozygotes; the latter make it possible to determine the particular pattern of chromosome 7 markers predictive of a cystic fibrosis homozygote in a specific family. However, neither test is appropriate for, applicable to, or informative in all families. The problems and potential of each approach are discussed.

Adult↗
PubMed1987

Increase of HLA-DR7 in pigeon breeder's lung in a Mexican population.

The phenotypes of the major histocompatibility complex, loci A, B, C, and DR, were studied in 48 patients with hypersensitivity pneumonitis induced by avian antigen (pigeon breeder's lung) and the results were compared to those obtained from 200 normal subjects of similar ethnic background. Furthermore, we analyzed the delta values of the observed and expected frequencies in the deduced haplotypes of the affected population. Our results showed a significant increase of the antigen HLA-DR7 (corrected P less than 0.001) in patients with pigeon breeder's lung and an equally important difference in the delta values of the haplotypes A1-B8, A25-B14, B35-DR4, and B4-DR5. In addition, the phenotypes of locus DQ were analyzed in 21 patients and 20 controls and no apparent differences were observed. These results suggest that a multifactorial genetic susceptibility associated at least in part with the major histocompatibility complex plays in important role in the development of this disease.

Adult↗