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Biomedical subjects

M E Hernandez

Publications and source records attributed to M E Hernandez.

At least 19 recordsLinked to original sources
PubMed2001

Extracellular electron transfer.

Results from several laboratories indicate that extracellular electron transfer may be a general mechanism whereby microoorganisms generate energy for cell growth and/or maintenance. Specifically, bacteria can use redox-active organic small molecules, generated outside or inside the cells, to shuttle electrons between reduced and oxidized compounds. Electron shuttling has now been reported for several different bacterial species, and exchanges of shuttling compounds may even syntrophically link diverse organisms in nature. Biofilm systems in both geological and clinical settings are likely to be important environments for metabolisms that employ extracellular electron transfer. Both structural and functional analyses suggest that electron shuttles and some virulence factors may be related to one another.

Bacteria↗
PubMed2000

Fertility ratio in male rats: effects after denervation of two pelvic floor muscles.

Fertility ratio is defined here as the proportion of females that a male can impregnate after a constant period of in-polygyny living. This ratio was investigated in male rats after denervation of two pelvic floor muscles, the pubococcygeus and iliococcygeus. Denervation was carried out by transecting the somatomotor branch of the pelvic nerve. The lesion did not modify the sexual behavior of males or their overall fertility, but decreased the weight of the ejaculated seminal plug. Consequently, the number of days living in cohabitation to induce pregnancy was increased in lesioned males (approximately 13 days) compared with intact and sham animals (approximately 5 days). These results showed that the fertility ratio was optimal when intact/sham males cohabited with females for two consecutive estrous cycles, but that lesioned males needed up to four cycles to induce most pregnancies. Two hypotheses are raised by our results. The first is that pelvic floor denervation decreases the forceful tension required to expel the semen from the prostatic urethra to the vagina, then an incomplete seminal plug is expelled. The second is that denervation cut afferent fibers that reflexively promote the continence of the semen deposited in the prostatic urethra during seminal emission, allowing some to leak out before ejaculation. The latter hypothesis can also explain the recovery of the fertility ratio in lesioned males. It could be a compensatory mechanism mediated by the pudendal nerve supply to the coccygeus muscle, the other pelvic floor muscle.

Abdominal Muscles↗
PubMed1999

Spinal organization and steroid sensitivity of motoneurons innervating the pubococcygeus muscle in the male rat.

Male rat motoneurons innervating the pubococcygeus muscle were located in the ventral nucleus of lamina IX at the sixth lumbar (L6) and first sacral (S1) spinal cord segments. Retrograde labeling with horseradish peroxidase-wheat germ agglutinin was transported up to second-order dendrites and revealed that these motoneurons have a "U-shaped arborization" of dendrites toward the intermediolateral and intermediomedial nuclei area of lamina VII. This dendritic organization makes a wide "final common path" that probably integrates afferent information from several sources, accounting for the participation of the pubococcygeus muscle in autonomic and somatic processes, such as those related to micturition and reproduction. Castration produced a decrement in the morphometry of these motoneurons. A main effect was a decrement in dendritic length. Steroid replacement indicated that testosterone and estradiol, but not dihydrotestosterone, are able to induce a recovery of morphometric alterations. However, estrogen induced recovery after 2 weeks of treatment, whereas testosterone took 4 weeks. Thus, it is proposed that supraspinal aromatization of testosterone in the male central nervous system might be an important process for the appropriate organization of the pubococcygeus muscle motoneurons and that estradiol seems to need a shorter time of action than testosterone because of differential up-regulation and down-regulation of steroid receptors.

Animals↗
PubMed1992

Risk of needle-stick injuries in the transmission of hepatitis C virus in hospital personnel.

To assess the risk to hospital personnel of acquiring an hepatitis C virus (HCV) infection as a result of occupational exposure to needle-stick injuries, 81 employees who had parenteral exposure to an anti-HCV-positive source were followed for 12 months. None developed hepatitis and anti-HCV testing by a second-generation ELISA system of serum samples collected on the day of exposure and at 3, 6 and 12 months was negative. Consequently, a low efficacy of needle-stick injuries in the transmission of HCV in hospital personnel may be suggested.

Follow-Up Studies↗
PubMed1989

Fulminant liver failure and pancreatitis associated with the use of sulfamethoxazole-trimethoprim.

We report the case of a 26-yr-old patient with fulminant liver failure and acute hemorrhagic pancreatitis secondary to the use of trimethoprim-sulfamethoxazole (Bactrim DS). Our patient presented with skin rash and decreased C3 and C4 levels, which we believed was due to a hypersensitivity reaction secondary to the sulfonamide component (sulfamethoxazole). To our knowledge, this is the first case reported in which sulfamethoxazole-trimethoprim has been implicated as a cause of fulminant liver failure and acute hemorrhagic pancreatitis simultaneously, and emphasizes the need of discontinuing this medication as soon as there is evidence of liver and pancreatic dysfunction.

Adult↗
PubMed1989

Fulminant idiopathic pseudomembranous colitis.

Pseudomembranous colitis is characterized by inflammatory plaques and pseudomembranes on the colonic mucosa. The disorder most commonly occurs after the use of antibiotics, which allow overgrowth of Clostridium difficile, a spore-forming, gram-positive rod that produces a toxin. Overgrowth of Staphylococcus aureus can also produce pseudomembranous colitis. In rare cases, pseudomembranous colitis is not associated with antibiotic use. When C. difficile is present, vancomycin or metronidazole usually produces a prompt response. In idiopathic cases, surgery may be required.

Aged↗
PubMed1983

Pyogenic liver abscess.

The primary source of pyogenic liver abscess is undetermined in about 30 percent of cases. Escherichia coli, microaerophilic streptococci and Bacteroides fragilis are among the common pathogens. Some cases can be treated with antibiotics alone; others require surgical management. With improved methods of diagnosis and therapy, the mortality rate is now 10 percent or less.

Adult↗