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Biomedical subjects

A C Toback

Publications and source records attributed to A C Toback.

16 recordsLinked to original sources
PubMed1994

Molecular defects of uroporphyrinogen decarboxylase in a patient with mild hepatoerythropoietic porphyria.

The molecular defect of uroporphyrinogen decarboxylase (UROD) was examined in a patient with mild hepatoerythropoietic porphyria. To elucidate the UROD defect, we cloned UROD cDNAs from EBV-transformed lymphoblastoid cells of the proband using reverse transcriptase-polymerase chain reaction. Nucleotide sequence analysis of the cloned UROD cDNAs revealed two separate missense mutations, each occurring in a separate allele. One mutation was a Val134-->Gln transition, and was due to three sequential point mutations (T417G418T419-->CCA); the other mutation was a His220-->Pro transition (A677-->C). UROD phenotype studies demonstrated that the TGT-->CCA mutation was inherited from the father, and the A-->C mutation was inherited from the mother. In contrast to the null activity previously described for a mutant UROD from a patient with familial porphyria cutanea tarda, these mutant URODs had subnormal but substantial enzyme activities, when expressed in Chinese hamster ovary cells. This is the first demonstration of a mutation caused by three sequential base substitutions.

Adult↗
PubMed1992

Skin care in the space environment.

Envisioned in the 21st century is the United States Space Program's establishment of a permanent human presence in a space station and a moon colony. Mid-21st century humans will take part in an exploratory trip to Mars from the moon (Collins, 1988; Ride, 1987). Fundamental to achieving these space goals will be human health care management. Skin, the largest human organ, will require care. The purpose of this article is to provide an understanding of skin care in the space environment.

Humans↗
PubMed1991

A new adventure.

Explore the source record for details and available documents.

Aerospace Medicine↗
PubMed1991

Space dermatology: a specialty in evolution.

The last thirty years have demonstrated the ability of humans to survive both brief and prolonged durations of microgravity in the unique environment of space. The maintenance of health and well-being during spaceflight has been the focus of physicians and health care personnel involved in space medicine. It follows that dermatology will become a defined component of space medicine, as skin-related physiology and subsequent disorders are elucidated and as health maintenance protocols are developed. This information will become part of the core of what can be called space dermatology.

Aerospace Medicine↗
PubMed1989

Manifesto of space medicine: the next dermatologic frontier.

As the fields of astronomy, cosmology, and space travel move rapidly forward, so must space medicine. The manned space program and medical knowledge and support have developed in tandem. Dermatology will play a fundamental role in survival during space flight. This paper reviews past, present, and future accomplishments of the space program as they relate to medicine and characterizes some of dermatology's multiple roles in the future. It further explores the immunologic alterations noted during space flight and the attendant implications for health and well-being both in flight and on return to Earth, or to an Earthlike environment.

Aerospace Medicine↗
PubMed1987

Hepatoerythropoietic porphyria: clinical, biochemical, and enzymatic studies in a three-generation family lineage.

Hepatoerythropoietic porphyria is caused by a marked deficiency in the activity of uroporphyrinogen decarboxylase, an enzyme that is essential for heme biosynthesis. It has been hypothesized that uroporphyrinogen decarboxylase deficiency is inherited as a homozygous defect in the disease. This suggestion has been supported by reports of a deficiency of the enzyme in parents of patients with the disorder. Further confirmation would be provided by demonstrating a similar uroporphyrinogen decarboxylase deficiency in the offspring of such patients. This study follows the enzymatic defect throughout three generations of a family in which a second-generation male was shown to have hepatoerythropoietic porphyria. Detailed biochemical and enzymatic analyses revealed a moderate deficiency of uroporphyrinogen decarboxylase in both the proband's parents and in his three children, all of whom were asymptomatic. The mildness of the clinical symptoms in the proband correlated with a higher level of residual enzyme activity than that in previously described patients. We conclude that clinically manifested hepatoerythropoietic porphyria results from the homozygous inheritance of a defect in the uroporphyrinogen decarboxylase gene, that the severity of clinical symptoms is probably related to the level of residual enzyme activity, and that the genetic defect of uroporphyrinogen decarboxylase in hepatoerythropoietic porphyria can be heterogeneous.

Adult↗
PubMed1987

Enhancement of granulopoiesis by lithium carbonate in a patient with hairy cell leukemia.

A 73-year-old patient with hairy cell leukemia and profound granulocytopenia both before and after splenectomy was treated with lithium carbonate. With serum lithium level maintained in the therapeutic range, granulocyte count steadily increased from a level below 200/mm3 to 800/mm3 over a two-week period. This trend reversed upon withdrawal of lithium. A second hematologic response occurred when the drug was reintroduced. The data support the contention that lithium carbonate may effectively stimulate granulopoiesis on a long-term basis, and this pharmacologic approach may be a useful adjunct to the management of hairy cell leukemia.

Aged↗
PubMed1987

Immunochemical study of uroporphyrinogen decarboxylase in a patient with mild hepatoerythropoietic porphyria.

Hepatoerythropoietic porphyria (HEP) is due to a marked deficiency of uroporphyrinogen (URO) decarboxylase, a cytosolic enzyme in the heme biosynthetic pathway. Using a radioimmunoassay method, we determined the concentration of URO decarboxylase protein in erythrocytes from a patient with mild HEP and found that the enzyme protein concentration had markedly decreased to less than 7% of the normal controls. This finding, however, was in contrast to the enzyme activity in the patient's erythrocytes, which was 16% of normal control levels and different from previously reported HEP cases in that erythrocytes in our patient contained disproportionately elevated URO decarboxylase activity in comparison to its immunoreactive material. Our findings suggests the possibility of a mutant isozyme in this patient that is not immunoreactive with an antibody raised against the normal enzyme.

Adult↗
PubMed1987

Eruptive vellus hair cysts.

Eruptive vellus hair cysts are an apparent developmental anomaly of vellus hair follicles that result in an asymptomatic papular eruption characteristically located on the anterior chest in young patients. A case of eruptive vellus hair cysts in reported, and the clinical and histologic findings are reviewed.

Child↗
PubMed1986

Phototoxicity from systemic agents.

Phototoxicity caused by systemic agents has been well described in the literature for only a handful of medications. Diagnosis rests initially upon the clinical recognition of a photodistributed eruption. Thereafter, histopathology and light testing with the patient on and off of the suspected medication should confirm the clinical suspicion. The creation of accurate and up-to-date tables of medications causing phototoxicity rests upon adequate documentation from the literature and thorough laboratory investigation of newly suspected agents.

Amiodarone↗
PubMed1985

Pulling boat hands: a unique dermatosis from coastal New England.

We report a previously unrecognized hand dermatosis, pulling boat hands (PBH), occurring in thirteen participants at the Outward Bound School on Hurricane Island, Maine. Painful and pruritic macules, plaques, and vesicles developed exclusively while subjects lived aboard a pulling boat, the school's open rowing/sailing craft. Nine of those affected were women and eight had Raynaud's phenomenon or vasospasm. These subjects experienced thirty episodes of PBH during May through October, 1978 to 1982. Histopathology revealed a superficial and deep lymphohistiocytic perivascular infiltrate, subepidermal blister formation, red blood cell extravasation, and dermal capillary thrombosis compatible with cold injury to the skin. All patients experienced prolonged percussion to their hands while rowing as well as a continuous environmental exposure to cold air, wind, humidity, ocean spume, and precipitation. These clinical, histopathologic, and environmental findings suggest a unique syndrome that combines the vascular effects of mechanical trauma from rowing with those of nonfreezing cold injury.

Adolescent↗
PubMed1985

Pathogenesis of cutaneous T-cell lymphoma.

Cutaneous T-cell lymphoma is a malignant disease whose behavior reflects its T-cell lineage. The biologic characteristics of the disease are understandable when viewed from a perspective of normal T-cell-skin interactions. Thus, it is of no surprise that this malignancy of helper T lymphocytes usually demonstrates a remarkable affinity for the skin at the outset and that, coincident with decreased dependence upon this unique environment, the extent and aggressiveness of disease increases. Although the inciting event responsible for the development of cutaneous T-cell lymphoma is unknown, a mechanism for local growth and distant expansion of malignant cells has been postulated in terms of IL-2-dependent and -independent growth phases. As our vision into the cellular and subcellular workings of this malignancy becomes more acute, specific therapeutic and preventive measures will emerge.

Cell Differentiation↗
PubMed1984

Splenic torsion. An unusual cause of splenomegaly.

A 28-year-old woman who presented with acute abdominal pain and splenomegaly was found to have little functioning splenic tissue on liver-spleen scan but a large homogeneous spleen by computerized axial tomography. Laparotomy revealed torsion of the splenic pedicle and extensive splenic infarction. The presentation, pathophysiology, and diagnostic difficulties of this case are discussed. Splenic torsion should be considered in the differential diagnosis of painful splenomegaly.

Adult↗