Biomedical subjects
Publications and source records attributed to M Reyes.
A rare case of a female patient with a 47,XYY karyotype is described. She had normal female external genitalia, bilateral testes, rudimentary Fallopian tubes and no uterus. Molecular analysis revealed a normal SRY encoding sequence. The possible events in the etiology of this sex reversal entity are discussed.
In order to determine the significance of nuchal translucency thickness on the subsequent natural history of first-trimester fetuses with a chromosome translocation, seven consecutive cases diagnosed between 11 and 13 weeks of gestation were reviewed. Nuchal translucency measurements were successfully obtained before chorionic villus sampling (CVS) in all cases. Three fetuses had an unbalanced translocation and all were associated with increased nuchal translucency and multiple anomalies at the detailed second-trimester scan. There were no survivors in this group. The remaining four fetuses had a balanced translocation; all had normal nuchal translucency thickness and no structural anomalies were detected in the second trimester. Three of these fetuses were born at > or =35 weeks of gestation and were phenotypically normal. However, an unexpected single fetal demise occurred in a dichorionic twin pregnancy at 28 weeks of gestation. It is concluded that nuchal translucency measurements provide important prognostic information on pregnancy outcome in first-trimester fetuses with a chromosome translocation. In parents with a known balanced translocation, the detection of increased nuchal translucency at 11-14 weeks of gestation is associated with unbalanced translocations, structural anomalies and poor pregnancy outcome.
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We present two cases of twin reversed arterial perfusion (TRAP) sequence complicated by severe polyhydramnios during the second trimester. Both cases were successfully managed at 27 and 26 weeks with ultrasound-guided intrafetal alcohol ablation of the acardiac twin and amniodrainage. The pump twins were delivered at 35 and 37 weeks, respectively, and both had uneventful postnatal courses. These cases suggest that, in the setting of severe polyhydramnios, prenatal intervention in TRAP sequence could certainly improve the otherwise poor prognosis of the pump twin. Targeting the main intra-abdominal vessel of the acardiac twin rather than its umbilical cord seems to be a good alternative in the prenatal treatment of these cases. The option of percutaneous intrafetal alcohol injection is widely available and less invasive, simpler and easier to perform than recently advocated endoscopic techniques.
There is considerable evidence for the existence of structural variants of growth hormone (GH). The chicken is a useful model for investigating GH heterogeneity as both size and charge immunoreactive-(ir) variants have been observed in the pituitary and plasma. The present study examined the size distribution of ir-GH in the pituitary gland of chicken, from late embryogenesis through adulthood. Pituitaries were homogenized in the presence of protease inhibitor, and the GH size variants were separated by SDS-PAGE, transferred by Western blotting, immunostained with a specific antiserum to chicken GH, and quantitated by chemiluminescence followed by laser densitometry (chemiluminescent assay). Under nonreducing conditions ir-GH bands of 15, 22, 25, 44, 50, 66, 80, 98, 105 and >110 kDa were observed. Both the relative proportion of the GH size variants and the total pituitary content varied with developmental stage and age. The proportion of the 15-kDa fragment was greatest in the embryonic stage, and then it decreased. The proportion of the monomeric 22-kDa form was lowest at 18 days of embryogenesis (dE) and highest at 20 dE. In contrast, the high MW forms (>/=66 kDa) were lowest in embryos, and they increased (P < 0.05) after hatching. The 22-, 44-, 66-, and 80-kDa forms were assayed for activity by radioreceptor assay following isolation by semipreparative SDS-PAGE. Only the 22-kDa GH variant showed radioreceptor activity. Under reducing conditions for SDS-PAGE, ir-GH bands of 13, 15, 18, 23, 26, 36, 39, 44, 48, 59 and 72 kDa were oberved, but most of the high MW form disappeared. There was a concomitant increase in the proportion of the monomeric band and of several submonomeric forms. The present data indicate that the expression, processing, and/or release of some if not all size variants are under some differential control during growth and development of the chicken.
PURPOSE: To bioengineer a corneal surface replacement using ex vivo expanded, cultured corneal epithelial stem cells seeded on a matrix derived from amniotic membrane and use this bioengineered graft to manage difficult ocular surface disease. METHODS: Fourteen patients with ocular surface disease unresponsive to standard medical and surgical treatments, including seven patients with presumed limbal stem cell deficiency were chosen for transplantation of a bioengineered composite corneal surface in eye each. Presumed corneal stem cells were harvested from either the patient's or related donor's limbus, expanded ex vivo, and cultivated on a carrier of modified human amniotic membrane. The resulting composite cultured tissue was transplanted to the ocular surface of the diseased eye, from which the abnormal tissue had been surgically removed. Ten patients received autologous grafts, and four received allogeneic grafts. RESULTS: A successful outcome, defined as restoration or improvement of vision, along with maintenance of corneal re-epithelialization and absence or recurrence of surface disease was obtained in 6 of the 10 patients with autologous procedures and in all 4 allogeneic transplants. Follow-up ranged 6-19 months with a mean of 13 months. CONCLUSIONS: This novel technique documents that presumed corneal epithelial stem cells can be harvested safely from the limbus, expanded successfully in vitro, and grown on denuded amniotic membrane. The resultant composite cultured tissue can be transplanted and appears to successfully manage eyes with difficult ocular surface disease, including those with stem cell deficiency. This technique minimizes the threat of damage or depletion to the contralateral or donor limbus.
Unusual health problems have been reported by Gulf War (GW) veterans, but no single etiology has been linked to these illnesses. This study was conducted to determine the association between self-reported GW deployment stressors and an illness defined by a combination of fatigue, mood-cognition, and musculoskeletal symptoms. A total of 1002 GW veterans from this cross-sectional survey of four Air Force units completed a self-administered questionnaire that asked about symptoms, demographic and military characteristics, and stressors during deployment. Severe and mild-moderate illness was positively associated with self-reports of pyridostigmine bromide use, insect repellent use and belief in a threat from biological or chemical weapons. Injuries requiring medical attention were only associated with severe illness. These results suggest a link between self-reported chemical, emotional, and physical exposures, and GW veterans' illness. Further research is needed to determine physiological and psychological mechanisms through which such stressors could have contributed to this symptom complex.
The maltose transporter FGK2 complex of Escherichia coli was purified with the aid of a glutathione S-transferase molecular tag. In contrast to the membrane-associated form of the complex, which requires liganded maltose binding protein (MBP) for ATPase activity, the purified detergent-soluble complex exhibited a very high level of ATPase activity. This uncoupled activity was not due to dissociation of the MalK ATPase subunit from the integral membrane protein MalF and MalG subunits. The detergent-soluble ATPase activity of the complex could be further stimulated by wild-type MBP but not by a signaling-defective mutant MBP. Wild-type MBP increased the V(max) of the ATPase 2.7-fold but had no effect on the K(m) of the enzyme for ATP. When the detergent-soluble complex was reconstituted in proteoliposomes, it returned to being dependent on MBP for activation of ATPase, consistent with the idea that the structural changes induced in the complex by detergent that result in activation of the ATPase are reversible. The uncoupled ATPase activity resembled the membrane-bound activity of the complex also with respect to sensitivity to NaN(3), as well as a mercurial, p-chloromercuribenzosulfonic acid. Verapamil, a compound that activates the ATPase activity of the multiple drug resistance P-glycoprotein, activated the maltose transporter ATPase as well. The activation of this bacterial transporter by verapamil suggests that a structural feature that is conserved among both eukaryotic and prokaryotic ATP binding cassette transporters is responsible for this activation.
BACKGROUND: The X syndrome, related to coronary disease in adults, could be possibly programmed priory to delivery, in children with intrauterine growth retardation. AIM: To measure serum lipids in newborns with symmetrical or asymmetrical intrauterine growth retardation. PATIENTS AND METHODS: One hundred thirty-five newborns with intrauterine growth retardation and 116 normal term newborns, with 38 to 41 gestational weeks, were studied. Total, HDL, and LDL cholesterol, triglycerides and apoproteins. A1 and B were measured in umbilical cord blood samples. RESULTS: No differences in total, HDL, LDL cholesterol, apoproteins A1 and B were observed between the study groups. Triglycerides were higher in newborns with intrauterine growth retardation, compared to normal term newborns (45 +/- 27 and 36 +/- 19 mg/dl respectively, p < 0.001). Differences in serum triglyceride levels respect to controls were observed in both male and female newborns with asymmetrical growth retardation. Likewise the differences respect to controls were observed in newborns with mild or severe but not with moderate growth retardation. CONCLUSIONS: Newborns with intrauterine growth retardation have higher triglyceride levels than normal term newborns.
In ecological models, the timing of amphibian metamorphosis is dependent upon rate of larval growth, e.g., tadpoles that experience a decrease in growth rate can initiate metamorphosis early. Recent authors have suggested that this plasticity may be lost at some point during the larval period. We tested this hypothesis by exposing groups of tadpoles of the gray treefrog, Hyla versicolor, to different growth schedules. In endocrine models, metamorphosis is dependent on thyroxine levels and thyroxine is antagonized by prolactin (amphibian larval growth hormone), consistent with the idea that a rapidly growing tadpole can delay metamorphosis. Thus, we also manipulated the rate of development by supplementing or maintaining natural thyroxine levels for half of the tadpoles in each growth treatment. All tadpoles that received thyroxine supplements metamorphosed at the same time regardless of growth history. They also metamorphosed earlier than tadpoles not treated with thyroxine. Tadpoles not given thyroxine supplements metamorphosed at different times: those growing rapidly during day 15-34 metamorphosed earlier than tadpoles growing slowly. Growth rate before day 15 and after day 34 had no effect on metamorphic timing. The difference in larval period between these rapidly growing tadpoles and their sisters given thyroxine treatments was less than the same comparison for tadpoles that grew slowly during the same period. This apparent prolactin/thyroxine antagonism did not exist after day 34. These results are consistent with the hypothesis of a loss of plasticity in metamorphic timing.
OBJECTIVE: We compared the pharmacokinetics of two methods for dosing gentamicin for the treatment of postpartum endometritis with the goal of achieving adequate peak serum concentrations (>12 mg/L) and prolonged trough levels below 2 mg/L. METHODS: Group-I subjects (n = 5) received intravenous gentamicin, 5 mg/kg per total body weight over 60 min., with a maximum dose of 500 mg. Group-II subjects (n = 17) were dosed intravenously according to the following formula: Dose = desired peak concentration (fixed at 14 mg/L) * (volume of distribution, i.e., 0.35 L/kg) * adjusted body weight (in kilograms). Serum gentamicin levels were obtained 1 hr. and 8-12 hr. after infusion of the second dose. Pharmacokinetic parameters for the subjects in each group were calculated according to standard formulas. RESULTS: Subjects in Group I had significantly higher doses and peak drug concentrations (P < 0.01), while in Group II, 76% of patients had peak levels less than desired (<12 mg/L). Both groups maintained trough levels of <2 mg/L in excess of 12 hr. CONCLUSIONS: Changing to the adjusted body weight formula for Group I, while maintaining a dose between 4 and 5 mg/kg, would reduce excessive peak concentrations. Using a calculated volume of distribution of 0.4 L/kg in Group II would improve peak serum concentrations to the desired levels. Both dosing regimens ensure adequate aminoglycoside pharmacokinetic parameters and avoid the need for monitoring serial serum drug concentrations, provided the expected clinical response is also achieved. While the first dosing formula is simpler to calculate, the second dosing formula allows for more individualized dosing considerations.
Bleomycin (BLM) induces lung injury and fibrosis in the murine lung and enhances tumor necrosis factor (TNF)-alpha and collagen mRNA expression in the murine lung. Amifostine is a cytoprotective agent that protects normal tissues from the cytotoxic effects of chemo- and radiation therapy. We investigated the effect of amifostine in BLM-induced lung injury in mice. Mice received intraperitoneal amifostine (200 mg/kg) 30 min before and/or 1, 3, and 7 days after an intratracheal injection of saline or BLM (4 U/kg). The animals were killed 14 days after BLM exposure, and their lungs were studied for TNF-alpha and collagen mRNA expression, hydroxyproline content, and histopathology. Light microscopy demonstrated that amifostine exacerbated the BLM-induced lung injury in mice. Increased TNF-alpha mRNA expression as a result of BLM exposure was not modulated by amifostine treatment. In contrast, amifostine treatment enhanced the BLM-induced expression of alpha(1)(I) procollagen mRNA in the lung. Similarly, mice treated with amifostine before BLM exposure accumulated significantly higher amounts of hydroxyproline (111 +/- 5 microg/lung) than BLM-treated animals (90 +/- 6 microg/lung). These data suggest that amifostine treatment exacerbates BLM-induced lung injury in mice.
Dual-phase stainless steels have been developed in order to reduce the nickel content, which is potentially responsible to an allergic reaction when these steels are used as medical or dental applications. In this study, two different dual-phase stainless steels (2205 and Z100) were electrochemically tested to evaluate their corrosion resistance in three corrosive solutions (i.e., synthetic saliva, 0.9% NaCl solution, and Ringer solution). Particularly, an attempt was made to correlate the corrosion resistance to a metallographic parameter, which is, in this study, the alpha/gamma phase ratio. It was concluded that (1) type 2205 stainless steel exhibited excellent corrosion resistance in all three corrosion media; however 2205 stainless steel decreases its corrosion resistance by increasing chloride concentration in tested electrolytes from synthetic saliva through 0.9% NaCl solution to Ringer solution. (2) X-ray diffraction analysis indicated that the alpha/gamma phase ratio of 2205 (1.735) was higher than that of Z100 (0.905). As a result, it is suggested that by increasing the alpha/gamma phase ratio the material shows more corrosion-prone behavior when being subjected to a hostile environment containing higher chloride ion concentration.
Despite considerable research on chronic fatigue syndrome (CFS) and conditions associated with unexplained chronic fatigue (CF), little is known about their prevalence and demographic distribution in the population. The present study describes the epidemiology and characteristics of self-reported CF and related conditions in a diverse urban community. The study used a cross-sectional telephone screening survey of households in San Francisco, followed by interviews with fatigued and nonfatigued residents. Respondents who appeared to meet case definition criteria for CFS, based on self-reported fatigue characteristics, symptoms, and medical history, were classified as CFS-like cases. Subjects who reported idiopathic chronic fatigue (ICF) that did not meet CFS criteria were classified as ICF-like cases. Screening interviews were completed for 8,004 households, providing fatigue and demographic information for 16,970 residents. Unexplained CF was extremely rare among household residents <18 years of age, but was reported by 2% of adult respondents. A total of 33 adults (0.2% of the study population) were classified as CFS-like cases and 259 (1.8%) as ICF-like cases. Neither condition clustered within households. CFS- and ICF-like illnesses were most prevalent among women and persons with annual household incomes below $40,000, and least prevalent among Asians. The prevalence of CFS-like illness was elevated among African Americans, Native Americans, and persons engaged in clerical occupations. Although CFS-like cases were more severely ill than those with ICF-like illness, a similar symptom pattern was observed in both groups. In conclusion, conditions associated with unexplained CF occur in all sociodemographic groups but appear to be most prevalent among women, persons with lower income, and some racial minorities.
The objective of this study was to identify factors explaining the correlations among unexplained severe fatigue of different durations (1-5 months or > or =6 months) and symptoms reported as being significant health problems during a preceding 4-week period. Between June and December of 1994, a cross-sectional, random digit dialing telephone survey was conducted among residents of San Francisco, California. All subjects who reported having severe fatigue lasting for > or =1 month and a random sample of nonfatigued subjects were asked to participate in a detailed telephone interview. Data from 1,510 individuals aged 18-60 years who did not have medical or psychiatric conditions that could explain their severe fatigue were analyzed. Common factor analyses identified three correlated factors (defined as "fatigue-mood-cognition" symptoms, "flu-type" symptoms, and "visual impairment") that explained the correlations among fatigue lasting for > or =6 months and 14 interrelated symptoms. No factor explained the correlations among fatigue lasting for 1-5 months and other symptoms. The combination of fatigue of > or =6 months' duration and selected symptoms overlaps with published criteria used to define cases of chronic fatigue syndrome (CFS). Although symptoms described in this study were reported as appearing within the preceding month, and CFS symptoms must have been present for the previous 6 months, these results provide empirical support for the interrelations among unexplained fatigue of > or =6 months' duration and symptoms included in the CFS case definition.
The N-methyl-D-aspartate (NMDA) subtype of glutamate receptor is one pathway through which excessive influx of calcium has been suggested to trigger ischemia-induced delayed neuronal death. NMDA receptors are heterooligomeric complexes comprised of both NR1 and NR2A-D subunits, in various combinations. NR2B-containing NMDA complexes exhibit larger, more prolonged conductances than those lacking this subunit. We tested the ability of the non-competitive, NR2B-selective NMDA antagonist eliprodil to (a) protect synaptic transmission in in vitro hippocampal slices from hypoxia, and (b) reduce ischemic delayed neuronal death in hippocampal organotypic slice cultures. Eliprodil markedly improved the recovery of Schaffer collateral-CA1 excitatory postsynaptic potentials following a 15 min hypoxic insult, with an EC50 of approximately 0.5 microM. In contrast to this functional protection, eliprodil did not reduce delayed death of CA1 pyramidal neurons in organotypic hippocampal slice cultures treated with severe hypoxia plus hypoglycemia, though it did potently protect CA3 pyramidal neurons in the same cultures. These data indicate that NMDA receptors containing NR2B subunits may play a role in long-term recovery of hippocampal synaptic function following ischemia/hypoxia. Furthermore, the selective protection of CA3, but not CA1, pyramidal neurons suggests that NR2B-containing NMDA receptors may preferentially contribute to an excitotoxic component of ischemia-induced delayed neuronal death.
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Entamoeba histolytica HMI:IMSS trophozoites were able to utilize human hemoglobin but not hemin as a sole iron source to grow in vitro. Proteases from crude extracts of E. histolytica degraded human, porcine, and bovine hemoglobins at pH 7.0. These proteolytic activities were found by electrophoresis in SDS-polyacrylamide gels copolymerized with hemoglobin, with apparent molecular weights of 116, 82, and 21 kDa, the 82-kDa protein being the most active protease against this substrate. The proteases were classified in the cysteine group since the activities were inhibited by l-trans-epoxysuccinylleucylamido(4-guanidino)butane, p-hydroxymercuribenzoate, iodoacetate, and N-ethylmaleimide and activated with dithiothreitol. Other pathogenic strains of E. histolytica showed the same pattern of hemoglobinases. These hemoglobin-degrading proteases could be playing an important role in iron acquisition by E. histolytica.