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Biomedical subjects

H Martinez

Publications and source records attributed to H Martinez.

At least 19 recordsLinked to original sources
PubMed1995

Vitamin B-12 deficiency and malabsorption are highly prevalent in rural Mexican communities.

Vitamin B-12 status of rural Mexicans was evaluated in two studies, 6 y apart. In the first, a single blood sample was collected from children and adults, including pregnant and lactating women. Prevalence of deficient plasma vitamin B-12 values ranged from 19% to 41% among groups, but plasma folate status was normal in all individuals. Breast milk vitamin B-12 concentration was low in 62% of samples. The second study was conducted in 219 children aged 18-36 mo in five communities, whose prevalence of deficient and low plasma vitamin B-12 concentrations, respectively, was 8% and 33% on entry, 3% and 22% 6 mo later, and 7% and 29% 12 mo later. Prevalence of low holotranscobalamin II concentrations, indicating malabsorption of the vitamin, averaged 18-40% across the three same periods. Both vitamin B-12 status indicators differed significantly between communities. The widespread vitamin B-12 deficiency was probably caused by malabsorption, perhaps exacerbated by low dietary intake and, for young children, maternal depletion of the vitamin.

Adult↗
PubMed1991

Clinical, radiographic, and hemodynamic correlations in chronic congestive heart failure: conflicting results may lead to inappropriate care.

PURPOSE: Clinical and radiographic examinations are commonly used for estimating severity and titrating therapy of chronic congestive heart failure. The purpose of this study was to establish the relationship between findings on history, physical examination, chest roentgenogram, and pulmonary capillary wedge pressure (PCWP). PATIENTS AND METHODS: Fifty-two consecutive patients with chronic congestive heart failure, referred for evaluation for heart transplantation, were studied; all patients underwent history, physical examination, upright chest roentgenogram, and cardiac catheterization. The mean left ventricular ejection fraction was 0.19 +/- 0.06. Patients were divided into three groups according to their PCWP: Group 1, normal PCWP (less than or equal to 15 mm Hg, n = 19); Group 2, mild to moderately elevated PCWP (16 to 29 mm Hg, n = 15); Group 3, markedly elevated PCWP (greater than or equal to 30 mm Hg, n = 18). RESULTS: Physical and radiographic signs of congestion were more common in the groups with higher PCWP, but they could not be used to reliably separate patients with different filling pressures. Physical findings (orthopnea, edema, rales, third heart sound, elevated jugular venous pressure) or radiographic signs (cardiomegaly, vascular redistribution, and interstitial and alveolar edema) had poor predictive value for identifying patients with PCWP values greater than or equal to 30 mm Hg. These findings had poor negative predictive value to exclude significantly elevated PCWP (greater than 20 mm Hg). Radiographic pulmonary congestion was absent in eight (53%) patients in Group 2 and seven (39%) in Group 3. In patients in Group 2 and 3, those without radiographic congestion were in a better New York Heart Association functional class (3.5 +/- 0.5 versus 2.8 +/- 0.6, p less than 0.01). There was good correlation between right atrial pressure and PCWP (r = 0.64, p less than 0.001). A normal right atrial pressure had no predictive value, but a pressure greater than 10 mm Hg was seen in all but one patient with a PCWP value greater than 20 mm Hg. CONCLUSION: Clinical, radiographic, and hemodynamic evaluations of chronic congestive heart failure yield conflicting results. Absence of radiographic or physical signs of congestion does not ensure normal PCWP values and may lead to inaccurate diagnosis and inadequate therapy. It is not known whether therapy aimed at normalizing PCWP is superior to relieving clinical and radiographic signs of congestion.

Adult↗
PubMed1991

Household size, food intake and anthropometric status of school-age children in a highland Mexican area.

Large household size is widely regarded as a risk factor for malnutrition in developing countries, particularly for infants and young children. This study examines the extent to which household size is related to nutritional status in school-age children in the Solis Valley in highland Mexico. The relationships of food intake, anthropometric measures, and household size are assessed in a sample of 110 children (7-9 years of age), who were followed longitudinally for a minimum of one year as part of the Collaborative Research Support Program on Food Intake and Human Function. Diets in the valley are characterized by very low intake of animal food products and are heavily dependent on maize, which is primarily home-produced. Growth faltering is pervasive; the mean Z score for height-for-age in the sample is--1.6 of the NCHS reference standard. Children from larger households are significantly shorter and consume diets of poorer quality, as assessed by intake of foods from animal sources. These relationships remain statistically significant in regression analyses that control for household economic status. It therefore appears that the resources available to households in the Solis Valley are inadequate to buffer children in even more advantaged households from the stresses of maintaining large families.

Anthropometry↗
PubMed1990

Solid-state chemistry and crystal structure of cefaclor dihydrate.

Cefaclor [7-(D-2-amino-2-phenylacetamido)-3-chloro-3-cepham-4-carboxy lic acid] crystallizes as the dihydrate. Crystals belong to space group P21, with a = 10.626(3), b = 7.1288(9), c = 14.124(3), and beta = 121.6(2). The structure was solved using direct methods and refined to an R of 0.0535. The bond lengths, angles, and conformation determined are as expected for cephalosporins. The two water molecules are held in the crystal differently. The 13C solid-state NMR spectrum of cefaclor dihydrate is also reported and is consistent with its crystal structure.

Cefaclor↗
PubMed1989

Cord blood lipoprotein-cholesterol: relationship birth weight and gestational age of newborns.

Umbilical plasma levels of lipoproteins-cholesterol were measured in 60 premature (less than 37 weeks), 60 small for gestational age (SGA, greater than 37 weeks), and 60 full term newborns (greater than 37 weeks) to ascertain the relationship between gestational age, infant's weight and concentration of plasma lipoprotein cholesterol. Umbilical levels of total cholesterol (TC), unesterified cholesterol (UC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) in premature newborns were significantly higher (P less than .001) than in term infants. The levels of TC, UC, HDL-C and very low density lipoprotein cholesterol (VLDL-C) were substantially higher (P less than .05) in umbilical cord plasma of SGA newborns than in cord plasma of full term newborns. Lecithin:cholesterol acyltransferase activity in cord plasma was indirectly assessed by measuring the ratio of esterified cholesterol to unesterified cholesterol (CE/UC). This ratio was significantly lower (P less than .01) in preterm and SGA than in full term newborns. In addition, plasma TC, UC, LDL-C and HDL-C levels were inversely correlated with gestational age of newborns. By contrast, CE/UC ratio had an inverse correlation with gestational age and HDL-C of the newborns. These findings suggest that the levels of TC in newborns are regulated by the uptake of LDL-C by the fetal adrenal and, additionally, by the lecithin:cholesterol acyltransferase (LCAT) activity of newborn plasma. Only by careful follow-up of hyperlipidemic neonates can the true incidence of familial hyperlipoproteinemia and the value of early diagnosis be assessed.

Birth Weight↗
PubMed1988

Rapid reinfection by Giardia lamblia after treatment in a hyperendemic Third World community.

In a peri-urban shanty town in Lima, Peru, that was hyperendemic for Giardia lamblia, 44 children aged between 0.9 months and 10 years were effectively treated for Giardia lamblia with tinidazole. Stools were examined weekly in the 6 months after treatment to determine the rate of reinfection, and after reinfection stools continued to be examined. 98% of the children became reinfected with Giardia lamblia within 6 months, and after reinfection stool excretion of the parasite lasted a mean (SD) of 3.2 (3.3) months. The children's mean stool pH and their mean stool fat index was unaffected by Giardia lamblia reinfection. Treatment of all symptomless Giardia lamblia infections in a developing country hyperendemic for the disease is of questionable value because of rapid reinfection.

Animals↗
PubMed1988

Modification of bronchial blood flow during allergic airway responses.

Ascaris suum antigen effects on mean airflow resistance (RL) and bronchial arterial blood flow (Qbr) were studied in allergic anesthetized sheep with documented airway responses. Qbr was measured with electromagnetic flow probes, and supplemental O2 prevented antigen-induced hypoxemia. Aerosol challenge with this specific antigen increased RL and Qbr significantly. Cromolyn sodium aerosol pretreatment prevented antigen-induced increases in RL but not in Qbr. Intravenous cromolyn, however, prevented increases in Qbr and RL, suggesting a role for mast cell degranulation in both bronchomotor and bronchovascular responses to antigen. Antigen-induced increases in Qbr were not solely attributable to histamine release. Indomethacin pretreatment attenuated the antigen-induced increase in Qbr, thus suggesting that vasodilator cyclooxygenase products contribute to the vascular response. Antigen challenge significantly decreased Qbr after indomethacin and metiamide pretreatment, which suggests that vasoconstrictor substances released after antigen exposure also modulate Qbr; however, released vasodilators overshadow vasoconstrictor effects. Thus antigen challenge affects Qbr by locally releasing histamine and vasodilator prostaglandins as well as vasoconstrictor substances. These effects were independent of antigen-induced changes in systemic and pulmonary hemodynamics.

Airway Resistance↗
PubMed1988

Longitudinal study of plasma lipids and lipoprotein cholesterol in normal pregnancy and puerperium.

Plasma lipids and lipoprotein cholesterol distribution were measured in 60 normal pregnancies studied longitudinally at 12, 20, 28, and 36 weeks of gestation and 3 and 40 days postpartum. Total cholesterol, unesterified cholesterol, phospholipids, triglycerides and cholesterol in low- and very-low-density lipoproteins rose progressively during pregnancy. Maximal values were reached at 36 weeks for total cholesterol, unesterified cholesterol and low-density lipoprotein cholesterol and at partum for triglycerides, very-low-density lipoprotein cholesterol and phospholipids. High-density lipoprotein cholesterol was hardly affected by pregnancy. During the second half of pregnancy and postpartum period, high-density lipoprotein cholesterol was consistently and negatively correlated with triglycerides and very-low-density lipoprotein cholesterol. In each period studied total cholesterol showed very high positive correlation with low-density lipoprotein cholesterol but a weak correlation with high-density lipoprotein cholesterol.

Cholesterol↗
PubMed1988

[Characteristics of the silver-stained nucleoli in blast elements of various diameters from patients with acute leukemia].

Using silver staining, a study was made of the activity of ribosomal cistrons (RC) in proliferating and non-proliferating subpopulations of bone marrow and peripheral blood blasts, taken from 33 patients with acute non-lymphoblastic leukemia and from 17 patients with acute lymphoblastic leukemia. All the blasts including non-proliferating ones were revealed to synthesize ribosomal RNA (rRNA). The RC activity of large blasts was higher than that of small ones. A significant difference (P less than 0.01) in RC activity between lymphoid and non-lymphoid blasts was found. The relation between nucleolar organizer activity of blasts and their proliferating potentials is discussed, in addition to a possibility for practical use of the above mentioned data.

Bone Marrow↗
PubMed1988

Plasma lipids and high density lipoprotein cholesterol in maternal and umbilical vessels in twin pregnancies.

Total cholesterol (TC), triglycerides (TG), phospholipids (PL), Unesterified cholesterol (UC) and high-density lipoprotein cholesterol (HDL) were measured in 30 plasmas from twin pregnant women and their newborns, and 60 maternal single infant pairs. Blood samples were obtained simultaneously from maternal vein, umbilical artery and umbilical vein at the moment of partum. TG from twin pregnant mothers was much higher and HDL-C lower than that from single pregnant maternal plasma TC, TG and PL in umbilical cord vessels showed no differences between twin and single newborns. There was a weak, but statistically significant, positive correlation between maternal and fetal levels of PL in both groups. A high difference between TC, TG and PL in umbilical venous and umbilical arterial plasma was found These data suggest that some fetal lipid moieties derived from maternal plasma. But data about fetal body composition indicate that contribution of maternal lipids to the fetus is of small quantitative importance.

Adult↗
PubMed1987

Preoperative cystoscopic findings in resectable rectal adenocarcinoma.

Forty-nine patients underwent preoperative cystoscopy prior to surgical resection for adenocarcinoma of the rectum. There were 30 men and 19 women ranging in age from 26 to 78 years, with a median age of 59 years. Surgical resections consisted of abdominoperineal resection, posterior exenteration, or total pelvic exenteration. Twenty patients had positive findings on preoperative cystoscopy while 29 had negative findings. Of the 20 patients with positive cystoscopic findings, eight (40%) had either urologic symptoms or abnormal microscopic findings on urinalysis; however, only one of these eight patients had tumor invasion of the bladder wall at cystoscopy, while the remaining seven had associated benign conditions. In the 29 cystoscopy procedures in which findings were negative, only three patients (10%) had urologic symptoms or abnormal results of urinalysis, none of which were secondary to the rectal carcinoma. We conclude that urinary symptoms can be misleading and unreliable when predicting neoplastic involvement of the bladder by carcinoma of the rectum because of the high incidence of associated benign disorders of the bladder. Therefore, cystoscopy does not have a useful role in staging patients undergoing surgery for rectal carcinoma in terms of local tumor extension.

Adenocarcinoma↗
PubMed1987

The solid-state decarboxylation of the diammonium salt of moxalactam.

This paper reports studies of the solid-state chemistry of the diammonium salt of moxalactam. The methods employed include X-ray crystallography, molecular mechanics calculations, thermogravimetric analysis, and high-pressure liquid chromatography. The crystal structure shows that the malonic acid amide functionality in crystals of the diammonium salt is not planar. If the common decarboxylation mechanism is operating, then considerable rotation would be required for this functionality to attain coplanarity. Simultaneous HPLC and thermogravimetric analysis studies indicate that the decarboxylation of the diammonium salt of moxalactam is preceded by desolvation. Molecular mechanics calculations indicate that the barrier to rotation of the malonic acid amide functionality is relatively small in the dehydrated crystals, perhaps explaining the facile decarboxylation of this antibiotic. Alternatively, the amorphous desolvated crystals may allow enough molecular freedom for the malonic acid amide functionality to attain coplanarity and decarboxylate.

Chromatography, High Pressure Liquid↗