PubMed Health⌕ Search

Biomedical subjects

M R Gomez

Publications and source records attributed to M R Gomez.

At least 19 recordsLinked to original sources
PubMed2001

Simple and rapid determination of nevirapine in human serum by reversed-phase high-performance liquid chromatography.

Nevirapine is an antiretroviral agent belonging to the class of non-nucleoside reverse transcriptase inhibitors. We describe a fast, simple isocratic reversed-phase high-performance liquid chromatography method with a 30-mm long column for assaying nevirapine in human serum. After deproteinization of 200 microl serum samples with 50% trichloroacetic acid, the supernatant was injected into a reversed-phase C18 column, using 10 mM phosphate buffer (pH 5)-acetonitrile (82:18, v/v) as the mobile phase. Peak detection was performed at 240 nm. Nevirapine retention time was 2 min. The method was validated over 0.1-10 microg/ml and the assay was linear over this concentration range (r2>0.998). Within- and between-day precisions were less than 5.4%. The lower limit of quantification was 0.1 microg/ml. Nevirapine in human serum samples was stable for 2 days at 20-25 degrees C, 15 days at 4 degrees C and 3 months at -20 degrees C.

Anti-HIV Agents↗
PubMed1998

Tuberous sclerosis complex consensus conference: revised clinical diagnostic criteria.

At the recent tuberous sclerosis complex consensus conference, the clinical diagnostic criteria for tuberous sclerosis complex were simplified and revised to reflect both new clinical information about tuberous sclerosis complex and an improved understanding of the disorder derived from molecular genetic studies. Based on this new information, some clinical signs once regarded as pathognomonic for tuberous sclerosis complex are now known to be less specific. No single sign is present in all affected patients, and there is no proof that any single clinical or radiographic sign is absolutely specific for tuberous sclerosis complex. Accordingly, the clinical and radiographic features of tuberous sclerosis complex have now been divided into major and minor categories based on the apparent degree of specificity for tuberous sclerosis complex of each feature. A definitive diagnosis of tuberous sclerosis complex now requires two or more distinct types of lesions, rather than multiple lesions of the same type in the same organ system. Although diagnosis on purely clinical grounds can continue to be difficult in a few patients, there should be little doubt about the diagnosis for those individuals who fulfill these strict criteria. Couples with more than one child with tuberous sclerosis complex, no extended family history, and no clinical features of tuberous sclerosis complex are more likely to have germline mosaicism for tuberous sclerosis than nonexpression of the mutation. Germline mosaicism, while fortunately rare, will not be suspected from either diagnostic criteria or molecular testing until a couple has multiple affected children. Genetic counseling for families with one affected child should include a small (1% to 2%) possibility of recurrence, even for parents who have no evidence of tuberous sclerosis complex after a thorough diagnostic evaluation.

Angiofibroma↗
PubMed1997

Purification of bovine alpha-lactalbumin by immobilized metal ion affinity chromatography.

The milk protein alpha-lactalbumin was isolated from bovine whey protein concentrate solution by immobilized metal ion affinity chromatography (IMAC) using Cu(II)-Chelating Sepharose Fast Flow. Stepwise pH (5.5-3.8) changes in sodium acetate buffer were used to elute the protein selectively, at which time it was concentrated and reapplied to an uncharged Chelating Sepharose Fast Flow column to remove the contaminating Cu(II) ions. A purity of 90% and recovery of 80% was achieved. The described method appears to be suitable for isolation of alpha-lactalbumin in a form adequate for milk formula engineering.

Animals↗
PubMed1997

Neonatal presentation of autosomal dominant polycystic kidney disease with a maternal history of tuberous sclerosis.

BACKGROUND: Childhood presentation of polycystic kidney disease has been reported with tuberous sclerosis complex (TSC). Recently some such cases have been shown to be due to combined deletion of the PKD1 and TSC2 genes, which lie close together on chromosome 16. The phenomenon of anticipation, whereby disease presentation occurs at a progressively earlier age in each generation, has been suggested to occur in autosomal dominant polycystic kidney disease (ADPKD). We have carried out a genetic study of a family in which these issues became clinically relevant. Neonatal presentation of polycystic kidneys occurred in an individual with a maternal family history of epilepsy and features of TSC without renal cystic disease. METHODS: Detailed historical and clinical profiles were gathered for three generations of the maternal and paternal families. Both parents underwent renal ultrasound scanning. Genomic DNA was obtained from affected and unaffected individuals from the maternal family and used for linkage analysis to gene loci for TSC. RESULTS: Renal cysts were not present in the mother by ultrasound. Linkage to TSC2 was found for members of the maternal family with clinical features of TSC. While a diagnosis of TSC was confirmed in her mother the child was found not to have inherited the disease-related allele. The father was found to have asymptomatic bilateral polycystic kidneys consistent with ADPKD. The presence of ADPKD in other paternal relatives could not be confirmed. CONCLUSIONS: The index case was found to have paternally inherited ADPKD with unusually early presentation. While at risk for concomitant maternal inheritance of TSC this diagnosis was ruled out by linkage analysis studies. The ability to clarify the true nature of a complex inherited condition greatly facilitates future management and counselling. The mechanisms underlying phenotypic heterogeneity in ADPKD remain to be clearly defined and are the subject of ongoing investigation.

Female↗
PubMed1997

Tuberous sclerosis complex: neonatal deaths in three of four children of consanguineous, non-expressing parents.

We describe here four sibs, born to consanguineous, healthy, asymptomatic parents. Three of these infants had a rapidly fatal course in the neonatal period; death was attributed to congestive heart failure with radiographic evidence of cardiomegaly in all of them. Necropsy was done in only one of them and showed the typical findings of tuberous sclerosis complex (TSC) in the central nervous system (CNS), kidneys, heart, and liver. The fourth sib, currently 2 years old, also has typical signs of TSC, namely hypomelanotic skin macules and calcified subependymal nodules. Both parents and a living maternal grandmother had appropriate examination, which included skin inspection under Wood's lamp, dental examination, fundoscopy, echocardiography, abdominal and renal ultrasound, and head CT and MRI scans, and no signs of TSC were found in either parent or in the only living grandmother. By history alone there is no other relative with signs or symptoms suggestive of TSC. Linkage analysis and loss of heterozygosity (LOH) investigations on a variety of lesions obtained from postmortem and tissue or blood specimens from all available family members studied failed to identify a microdeletion in the chromosomal regions where TSC genes are located. It is very unusual that in a single TSC family there were three consecutive neonatal deaths, and very likely that all had cardiac rhabdomyomas. Moreover, to the best of our knowledge, there are no previous reports of TSC families with more than one affected sib, unusually severe manifestations of the disease, and completely normal, consanguineous parents.

Child, Preschool↗
PubMed1997

Cortical tuber count: a biomarker indicating neurologic severity of tuberous sclerosis complex.

The relationship between the number of cortical tubers observed by magnetic resonance imaging (MRI) and the severity of cerebral dysfunction of tuberous sclerosis patients has been examined in a meta-analysis of the published literature. The literature review has identified five independent studies for examining the association. These studies consistently reveal that the cortical tuber count detected on MRI scans is increased among those with more severe cerebral disease. Severity of the cerebral dysfunction is measured by the seizure status and its control and by the developmental status and the level of mental retardation. Meta-analysis demonstrates that within a study population, the MRI-detected cortical tuber count is six times more likely to be above the median count for tuberous sclerosis patients with severe cerebral dysfunction (poor seizure control or moderate-severe retardation or both) than more mildly affected tuberous sclerosis patients. Similarly, across studies, moderately to severely affected patients are five times more likely to have greater than seven MRI-detected cortical tubers than those more mildly affected. These associations are both statistically significant and strong. The cortical tuber count is a biomarker that reasonably predicts the severity of cerebral dysfunction of tuberous sclerosis. Cortical tubers of tuberous sclerosis form in the early gestational period. The embryologic disruption determining the clinical severity of the cortical dysfunction of tuberous sclerosis is set in the early gestational period.

Cerebral Cortex↗
PubMed1997

Risk factors for developing multiple sclerosis after childhood optic neuritis.

We reviewed the records of all children (younger than 16 years of age) who presented with a diagnosis of optic neuritis (ON) identified through the comprehensive records-linkage system at the Mayo Clinic and identified 94 cases between 1950 and 1988 with a documented history of idiopathic ON. Detailed follow-up information was available on 79 patients, with a median length of follow-up of 19.4 years. Life-table analysis showed that 13% of the 79 patients with isolated ON had progressed to clinically or laboratory-supported definite multiple sclerosis (MS) by 10 years of follow-up, 19% by 20 years, 22% by 30 years, and 26% by 40 years. Gender, age, funduscopic findings, visual acuity, or family history of either ON or MS did not predict the development of MS. The presence of bilateral sequential or recurrent ON increased the risk of developing MS (p = 0.002; hazard ratio = 5.09), whereas the presence of infection within 2 weeks before the onset of ON decreased the risk of developing MS (p = 0.060; hazard ratio = 0.24). This study of childhood ON supports the lower risk of recurrence and progression to MS compared with adults.

Adolescent↗
PubMed1996

Parenteral nutrition in low-birth-weight infants.

Parenteral nutrition has been used in the nutritional management of low-birth-weight infants for the past 25 years. Nonetheless, many aspects of the technique still are not completely understood. Further, Other aspects that are reasonably well understood frequently are not applied in clinical practice. As a result, infants requiring this therapy frequently do not benefit maximally from it. Some of the important issues concerning this technique are discussed, and some of the important questions that need to be addressed are identified. Answers to many of these important questions are necessary to further enhance the benefits and diminish the undesired consequences of this therapy for infants who require it.

Amino Acids↗
PubMed1996

Comparison of centrifugal and roller pump hemolysis rates at low flow.

We compared in vitro rates of hemolysis for a recently developed centrifugal pump with a conventional roller pump (10-10-00; Stöckert, Munich, Germany). Flow rates of 0.3 L/min and 1 L/min and a pressure of 200 mm Hg were chosen to simulate conditions during neonatal extracorporeal membrane oxygenation (ECMO). There was no significant difference in hemolysis rates between centrifugal and roller pumps (p = 0.57) nor between high and low flow (p = 0.86). The centrifugal pump caused no more blood trauma than the roller pump at the low-flow/high-pressure conditions required for neonatal ECMO. The Nikkiso pump is superior to roller pumps in size and priming volume (25 ml) and may permit development of a smaller and simpler ECMO system.

Animals↗
PubMed1995

Tuberous sclerosis and cardiac rhabdomyoma.

We conclude that echocardiographically detected cardiac rhabdomyomata are common in patients with tuberous sclerosis complex, and are more prevalent and prominent in the younger patient. Tumors regress in size or number, or both, in most patients aged < 4 years, and less so in older patients. Cardiac rhabdomyomata are associated with a higher incidence of preexcitation and may increase the risk for arrhythmia.

Adolescent↗
PubMed1995

Pulmonary tuberous sclerosis.

We describe the clinical presentation, pulmonary function tests, chest radiograph, and computed tomography findings, response to hormonal treatment, and duration of survival of nine patients with pulmonary involvement in tuberous sclerosis complex with follow-up over an average of 17 years (range, 1 to 35 years) since diagnosis. All patients were female, and the average age at onset of symptoms was 16 years (range, 3 months to 39 years); pulmonary symptoms did not develop until an average age of 33 years (range, 22 to 46 years). There was an average delay of 8 years before the correct diagnosis was made. The most common presenting clinical features were seizures, pneumothorax, bleeding into a renal angiomyolipoma, dyspnea, and typical skin changes. Pulmonary function tests commonly demonstrated obstruction to airflow and reduced single-breath diffusing capacity. Chest radiograph and computed tomography characteristically demonstrated diffuse interstitial infiltrates with cystic changes. Two asymptomatic patients with mild pulmonary involvement have remained in stable condition without hormonal therapy. The remaining seven patients had moderate to severe airflow obstruction; of these, five underwent hormonal therapy. Three patients had a clinical response to treatment. Two patients who did not receive hormonal treatment died of progressive respiratory failure. Most patients with pulmonary involvement in tuberous sclerosis have a slowly declining clinical course. Although the available data are limited, they suggest that a trial of hormonal therapy is recommended both for symptomatic patients and for those with declining pulmonary function. Tuberous sclerosis complex should be suspected in all patients with the diagnosis of lymphangioleiomyomatosis.

Adult↗
PubMed1995

Extrapulmonary lymphangioleiomyomatosis and lymphangiomatous cysts in tuberous sclerosis complex.

OBJECTIVE: To describe the clinical manifestations, imaging findings, and histologic features of extrapulmonary lymphangioleiomyomatosis (LAM) in the tuberous sclerosis complex (TSC). DESIGN: We retrospectively reviewed institutional medical records since 1940 to identify patients with TSC and extrapulmonary LAM. MATERIAL AND METHODS: Of 403 patients with TSC, 3 had pulmonary and extrapulmonary LAM and retroperitoneal lymphangiomatous cysts. The clinical, imaging, and histologic features of these three patients were summarized, including analysis of biopsy specimens by conventional histology, immunohistology, radiolabeled ligand-binding assays, and tissue culture. RESULTS: The three young women had characteristic dermatologic findings of TSC and pulmonary LAM. Two patients were of normal intelligence, and one had a recent history of contraceptive use. All three patients had intra-abdominal lymphangiomatous cysts, uterine LAM, and renal angiomyolipomas. Renal and uterine biopsy specimens demonstrated positive immunostaining for melanoma-related antigens and expression of estrogen and progesterone receptors by ligand-binding assay and immunohistology. Cells cultured from LAM tissue of one of the patients exhibited a mitogenic response to estradiol. CONCLUSION: Clinically significant extrapulmonary LAM is a rare manifestation of TSC and may occur in women with this disease who also have pulmonary LAM. The clinical features of these patients confirm the importance of sex steroids in the development of these lesions. Immunohistochemical findings suggest that LAM and angiomyolipomas have a neuroectodermal origin. The development of lymphangiomatous cysts in these patients is probably due to smooth muscle proliferation in lymph vessels, which can result in lymphatic obstruction.

Abdominal Neoplasms↗
PubMed1995

MR findings in tuberous sclerosis complex and correlation with seizure development and mental impairment.

PURPOSE: To correlate the findings on MR scans of the brain in patients with tuberous sclerosis complex with mental disability and the type and age at onset of the first seizure. METHODS: Patients with tuberous sclerosis complex who had MR brain scans were identified. The diagnosis was confirmed, and the clinical information on each patient was updated. The number, site, and area of abnormal signals were recorded on each scan. The presence of sulcal islands, gyral cores, and migration lines or wedges was recorded. RESULTS: Seventy-five patients were studied. Twenty-nine patients who had infantile spasms had more tubers than the 26 who presented with other types of generalized seizures. These patients had more tubers than the 15 patients with partial seizures. Significantly more tubers were found in patients with seizure onset before 1 year of age and mental disability. Gyral cores, sulcal islands, and radial migration lines or wedges were more common in patients with infantile spasms who had an early seizure onset and were mentally disabled. Patients who did not have seizures had no mental disability. CONCLUSIONS: A greater number of tubers occurred in patients who had infantile spasms, had their first seizure before 1 year of age, or had a mental disability. These features reflect the degree of cerebral dysfunction caused by the tubers. Gyral cores, sulcal islands, and migration lines or wedges also reflect cerebral dysfunction. MR scans correlate well with the clinical features and are valuable in assessing patients with tuberous sclerosis complex.

Age of Onset↗
PubMed1994

Occupational exposure to chlorinated aliphatic hydrocarbons: job exposure matrix.

A job exposure matrix combining features to increase the accuracy of exposure assessment was developed to evaluate cancer risks from workplace exposures to six chlorinated aliphatic hydrocarbons (CAHs). A detailed description of the matrix is provided to satisfy the need for more in-depth discussion of exposure assessment methods than is typical in today's epidemiologic literature. The matrix assigns semiquantitative estimates of the probability and intensity of exposure to each four-digit Standard Industrial Classification (SIC) and Standard Occupational Classification (SOC) code potentially associated with exposure to each CAH. The matrix also accounts for the changing patterns of use of the CAHs by decade from the 1920s to the 1980s. An algorithm combines these parameters to assign each study subject a unique lifetime probability of exposure and an estimated score of cumulative exposure for each CAH. These assignments can then become the subjects of analyses. The ability of the matrix to reduce the number of false positive exposure assessments is discussed and illustrated. A companion paper describes the detailed epidemiologic findings of this application of the matrix.

Algorithms↗
PubMed1994

Attenuation of acetaminophen hepatotoxicity in mice as evidence for the bioavailability of the cysteine in D-glucose-L-cysteine in vivo.

A substantial fraction of the cysteine added to total parenteral nutrition (TPN) solutions is converted to the corresponding thiazolidine derivative, while in solution with relatively large concentrations of glucose typical of TPN (700 mM and higher). It was recently reported (Roberts et al. (1987) J. Med. Chem. 30, 1891-1896) that this thiazolidine, D-glucose-L-cysteine (DGC), offered no significant protection against the hepatic injury caused by 5 mmol/kg of acetaminophen in mice, suggesting that the cysteine present as DGC is poorly bioavailable in vivo. In the present study, fasted male ICR mice given 1.6 or 2.6 mmol/kg of acetaminophen sustained hepatic injury, estimated by elevations in plasma alanine aminotransferase (ALT) activities. Administration of 2.5 mmol/kg of N-acetylcysteine (NAC) 1 h before acetaminophen given i.p. prevented the rise in plasma ALT activities, apparently through support of glutathione (GSH) synthesis. Administration of 2.5 mmol/kg of DGC prior to acetaminophen resulted in slightly lower mean plasma ALT activities than were observed in animals given saline before acetaminophen, but the effect was not statistically significant. When DGC was given 1 h before p.o. administration of 1.6 or 2.6 mmol/kg of acetaminophen, the protective effects of DGC were statistically significant (P < 0.01, 0.025, respectively), although NAC afforded significantly greater protection than did DGC at the higher dose of acetaminophen. Given 4 h before acetaminophen, DGC attenuated acetaminophen-induced increases in plasma ALT activities significantly, whereas NAC was without effect. These results indicate that the cysteine in DGC is at least partially bioavailable in vivo and, further, that DGC may function as a slow release formulation of cysteine.

Acetaminophen↗
PubMed1994

Total parenteral nutrition in necrotizing enterocolitis.

Total parenteral nutrition (TPN) is used both to prevent necrotizing enterocolitis (NEC) and to treat infants who develop the disease. Evidence for the efficacy of the technique in both settings is discussed. Several practical aspects of TPN also are discussed, as are a variety of theoretical considerations relevant to use of TPN either to prevent NEC or as an adjunct to treatment of the infant with the disease.

Enterocolitis, Pseudomembranous↗