Search PubMed⌕ Search

Biomedical subjects

M H Dang

Publications and source records attributed to M H Dang.

5 recordsLinked to original sources
PubMed1996

The mutation rate of the human mtDNA deletion mtDNA4977.

The human mitochondrial mutation mtDNA4977 is a 4,977-bp deletion that originates between two 13-bp direct repeats. We grew 220 colonies of cells, each from a single human cell. For each colony, we counted the number of cells and amplified the DNA by PCR to test for the presence of a deletion. To estimate the mutation fate, we used a model that describes the relationship between the mutation rate and the probability that a colony of a given size will contain no mutants, taking into account such factors as possible mitochondrial turnover and mistyping due to PCR error. We estimate that the mutation rate for mtDNA4977 in cultured human cells is 5.95 x 10(-8) per mitochondrial genome replication. This method can be applied to specific chromosomal, as well as mitochondrial, mutations.

Adult↗
PubMed1977

Necrotizing fasciitis: a persistent surgical problem.

Necrotizing fasciitis is a rare but specific clinical entity which, if not diagnosed early and treated aggressively, is rapidly fatal. The disease was first described during the Civil War and continues to be associated with a 50% mortality. The infectious process is diagnosed by the presence of a widespread fascial necrosis with extensive undermining of the adjacent tissues. The initial mechanism of injury as well as the location and etiologic agent of the suppurative fasciitis may vary. A review of 41 cases of necrotizing fasciitis occurring over a 22-year period disclosed an overall mortality of 39%. Most often, the mortality was related to the severity of the associated diseases and a failure to recognize the disease process promptly. The rate may be lowered by early recognition and prompt surgical intervention coupled with intensive supportive therapy.

Adolescent↗
PubMed1975

Complete occlusion of the infrarenal abdominal aorta: management and results in 64 patients.

Sixty-four patients with complete occlusion of the infrarenal abdominal aorta were reviewed. The clinical findings, diagnostic procedures, and surgical management are described. Sixty-one patients underwent thromboendarterectomy and bypass grafts from the infrarenal abdominal aorta to the iliac or common femoral arteries. Because purulent material was found in the retroperitoneum of two patients, the proximal anastomosis was performed to the descending thoracic aorta in one patient and to the upper abdominal aorta in the other. One patient underwent thromboendarterectomy and patch graft angioplasty. The hospital mortality rate was 4.6 percent. Sixty-one patients discharged from the hospital were followed (average length of follow-up was 37 months). There were three late deaths (4.9 percent). Two patients have had occlusion of one limb of their bypass grafts and, along with four others, have developed recurrent symptoms of vascular insufficiency of the lower extremities. These symptoms were due to progressive atherosclerotic occlusive disease of the distal arterial tree for which additional distal procedures were required.

Adult↗
PubMedDate not supplied

Mitochondrial DNA deletions are rare in the free radical-rich retinal environment.

We measured the levels of a somatic, 4977 bp deletion of mitochondrial DNA (mtDNA4977) in paired neural retinal and optic nerve tissues from 14 adults and 1 infant using a quantitative PCR assay. MtDNA is prone to free radical damage, and areas in the brain that are exposed to high levels of free radicals are observed to accumulate higher levels of the mtDNA4977 deletion. The levels of mtDNA deletions also increase with age in many tissues. Despite the presence of a free radical rich environment, mtDNA from the neural retina possessed extremely low mtDNA4977 levels (0.0001-0.001%). Deletion levels were always lower than those in the optic nerve from the same eye and do not appear to increase with age. Our results suggest that antioxidant defenses in the neural retina are effective in protecting mtDNA against oxidative damage.

Adolescent↗