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Biomedical subjects

D B Davis

Publications and source records attributed to D B Davis.

At least 19 recordsLinked to original sources
PubMed2001

Dysferlin protein analysis in limb-girdle muscular dystrophies.

Dysferlin is the protein product of the DYSF gene mapped at 2p31, which mutations cause limb-girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy. To date, nine autosomal recessive forms (AR-LGMD) have been identified: four genes, which code for the sarcoglycan glycoproteins, are associated with both mild and severe forms, the sarcoglycanopathies (LGMD2C, 2D, 2E and 2F). The other five forms, usually causing a milder phenotype are LGMD2A (calpain 3), LGMD2B (dysferlin), LGMD2G (telethonin), LGMD2H (9q31-11), and LGMD21 (19q13.3). We studied dysferlin expression in a total of 176 patients, from 166 LGMD families: 12 LGMD2B patients, 70 with other known forms of muscular dystrophies (LGMD2A, sarcoglycanopathies, LGMD2G), in an attempt to assess the effect of the primary gene-product deficiency on dysferlin. In addition, 94 still unclassified LGMD families were screened for dysferlin deficiency. In eight LGMD2B patients from five families, no dysferlin was observed in muscle biopsies, both through immunofluorescence (IF) and Western blot methodologies, while in two families, a very faint band was detected. Both patterns, negative or very faint bands, were concordant in patients belonging to the same families, suggesting that dysferlin deficiency is specific to LGMD2B. Myoferlin, the newly identified homologue of dysferlin was studied for the first time in LGMD2B patients. Since no difference was observed between patients mildly and severely affected, this protein do not seem to modify the phenotype in the present dysferlin-deficient patients. Dystrophin, sarcoglycans, and telethonin were normal in all LGMD2B patients, while patients with sarcoglycanopathies (2C, 2D, and 2E), LGMD2A, LGMD2G, and DMD showed the presence of a normal dysferlin band by Western blot and a positive pattern on IF. These data suggest that there is no interaction between dysferlin and these proteins. However, calpain analysis showed a weaker band in four patients from two families with intra-familial concordance. Therefore, this secondary deficiency of calpain in LGMD2B families, may indicate an interaction between dysferlin and calpain in muscle. Dysferlin was also present in cultured myotubes, in chorionic villus, and in the skin. Dysferlin deficiency was found in 24 out of a total of 166 Brazilian AR-LGMD families screened for muscle proteins (approximately 14%), thus representing the second most frequent known LGMD form, after calpainopathy, in our population.

Adult↗
PubMed2000

Myoferlin, a candidate gene and potential modifier of muscular dystrophy.

Dysferlin, the gene product of the limb girdle muscular dystrophy (LGMD) 2B locus, encodes a membrane-associated protein with homology to Caenorhabditis elegans fer-1. Humans with mutations in dysferlin ( DYSF ) develop muscle weakness that affects both proximal and distal muscles. Strikingly, the phenotype in LGMD 2B patients is highly variable, but the type of mutation in DYSF cannot explain this phenotypic variability. Through electronic database searching, we identified a protein highly homologous to dysferlin that we have named myoferlin. Myoferlin mRNA was highly expressed in cardiac muscle and to a lesser degree in skeletal muscle. However, antibodies raised to myoferlin showed abundant expression of myoferlin in both cardiac and skeletal muscle. Within the cell, myoferlin was associated with the plasma membrane but, unlike dysferlin, myoferlin was also associated with the nuclear membrane. Ferlin family members contain C2 domains, and these domains play a role in calcium-mediated membrane fusion events. To investigate this, we studied the expression of myoferlin in the mdx mouse, which lacks dystrophin and whose muscles undergo repeated rounds of degeneration and regeneration. We found upregulation of myoferlin at the membrane in mdx skeletal muscle. Thus, myoferlin ( MYOF ) is a candidate gene for muscular dystrophy and cardiomyopathy, or possibly a modifier of the muscular dystrophy phenotype.

Amino Acid Sequence↗
PubMed1995

Home care for the urban chronically ill elderly in the People's Republic of China.

This study examines the home care situation of seventy-five urban chronically ill men and women and their caregivers in three cities in the People's Republic of China. It documents the type of home care provided, the severity of illness, and the dependency in activities of daily living in order to appreciate the complexity of these care situations. The findings reveal that women serve as the caregivers in the majority of the cases and often they are elderly spouses with health problems of their own. The physical, social, psychological, and financial problems experienced by these patients create an enormous burden for the caregivers whether spouses or younger family members coming home from work to a second shift. If alternatives to home care, such as nursing homes, were available, 54 percent of these caregivers would be willing to institutionalize their elderly relative. All caregivers express the need for more assistance in providing home care. This study raises questions regarding the role of the family, the state, and specifically the health care system in caring for the elderly chronically ill in light of their increasing numbers in the population.

Activities of Daily Living↗
PubMed1994

Efficacy and complication rate of 16,224 consecutive peribulbar blocks. A prospective multicenter study.

Although usually safe, retrobulbar anesthesia and peribulbar anesthesia have potentially sight- and life-threatening complications. Although it has been suggested that peribulbar anesthesia is as effective and safer than retrobulbar anesthesia, no large study has addressed the true rate of complications. To determine the efficacy and safety of peribulbar anesthesia, this study prospectively examined 16,224 consecutive peribulbar blocks. Twelve centers in the United States, Germany, and Chile participated in the study. After a peribulbar block was administered, the degree of akinesia, amaurosis, percentage of supplemental blocks required, and side effects and complications occurring after the block and for six weeks were recorded. Perioperative and late optic nerve complications were included. To approximate a real-life situation, ophthalmologists, anesthesiologists, and certified registered nurse anesthetists performed the blocks. Ninety-five percent of patients achieved a 95% or greater degree of akinesia. The incidence of complications in the consecutive cases was low. Orbital hemorrhage occurred in 12 cases (0.74%). There was one globe perforation (0.006%), two expulsive hemorrhages (0.013%), one grand mal seizure (0.006%), and no cases of cardiac or respiratory depression or deaths. Peribulbar is as effective as retrobulbar anesthesia and appears to lead to fewer sight- and life-threatening complications, even when slightly different peribulbar techniques are used. This is especially true when the anesthetic is administered with a 1 1/4-inch or shorter needle with the eye in the primary position, followed by ten to 15 minutes of ocular compression.

Aged↗
PubMed1986

Posterior peribulbar anesthesia: an alternative to retrobulbar anesthesia.

Posterior peribulbar anesthesia is a safe alternative to retrobulbar anesthesia for ophthalmic surgery. Because the anesthetic is deposited outside the muscle cone, the potential for intraocular or intradural injection is greatly minimized. Furthermore, intraconal hemorrhage and direct optic nerve injury is avoided. We illustrate the details of our technique for posterior peribulbar anesthesia and describe our experience in over 1,600 cases.

Anesthesia, Local↗
PubMed1976

Quantitation of the viral DNA present in cells transformed by UV-irradiated herpes simplex virus.

Two cell lines biochemically transformed by UV-irradiated herpes simplex virus (HSV) each contain virus DNA. A comparison of the kinetics of reassociation of 3H-labeled HSV DNA in the presence and absence of either clone 139 (HSV-1 transformed) or clone 207 (HSV-2 transformed) DNA showed that the presence of transformed cell DNA increased the rate of reassociation of approximately 10% of the viral genome while having no effect on the remaining 90%. The Cot1/2 of this reaction was approximately 1,000 in each cell type, as compared to approximately 3,000 for the cellular unique sequences. These results suggest the presence of four to six copies of a 10% fragment of the virus DNA per cell. The DNA from a hamster fibroblast cell line morphologically transformed by UV-irradiated HSV-2 (333-8-9) did not affect the rate of reassociation of HSV-2 DNA, indicating that these cells had less than 3% of a viral genome present.

Cell Line↗