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Biomedical subjects

T Whitney

Publications and source records attributed to T Whitney.

6 recordsLinked to original sources
PubMed1999

Prophylactic mastectomy and inherited predisposition to breast carcinoma.

Relative to her risk of breast carcinoma, the woman with a BRCA1 or BRCA2 gene mutation can be managed either by intensive screening (with or without chemoprevention) or by prophylactic mastectomy. Although it would be preferable to avoid prophylactic surgery, the current level of screening technology and the rudimentary state of chemoprevention do not guarantee a good outcome with intensive surveillance. A review of the currently available data was undertaken to determine the efficacy of prophylactic surgery, intensive screening, and chemoprevention. An attempt then was made to extrapolate the efficacy of the various approaches to the management of women who carry BRCA1 or BRCA2 gene mutations. Intensive surveillance may not detect breast carcinoma at an early, curable stage in young women with BRCA1 or BRCA2 gene mutations because the growth rate of the tumors in these women most likely will be rapid and the density of the breast tissue may compromise detection. Chemoprevention is in its infancy, and its efficacy in this population is unknown. Conversely, prophylactic surgery may not be completely effective in preventing breast carcinoma. The authors are hopeful that sometime in the next decade advances in chemoprevention, screening technology, or breast carcinoma treatment will make mastectomy obsolete. However, for the time being prophylactic mastectomy has attributes that make it an alternative for this population that must be considered. Careful discussion of all options is essential in the management of these women.

BRCA1 Protein↗
PubMed1995

Planning mandibular distraction: preliminary report.

Normal lengths of the vertical ramus, body, and angle of the mandible at different ages are presented. Before mandibular distraction is embarked on, the extent of the deficiency of the mandible is assessed. The length of the vertical ramus and body are measured on cephalometric radiographs or three-dimensional computed tomography (3D CT) scans. Deficiency of the length of the mandible is calculated. The position of the pin placement angle (from the horizontal ramus) is calculated by means of the following formula: 180 degrees minus mandibular angle times vertical ramus deficiency divided by total deficiency. Placing the pins correctly will result in correction of the vertical ramus and body deficiency of the mandible and the excessively obtuse angle of the mandible will become more acute.

Bone Lengthening↗
PubMed1989

Excitatory effect of substance P in parasympathetic ganglia of cat urinary bladder.

Intra-arterial administration of substance P (0.1-50 micrograms/kg) to the urinary bladder of the cat produced slow-onset and sustained bladder contractions, asynchronous firing of bladder postganglionic nerves, and facilitation of nicotinic transmission in bladder ganglia. Intracellular recording from bladder ganglia in vitro revealed that substance P depolarized ganglion cells and initiated burst of action potentials (maximal frequency 6-7 Hz). The ganglionic excitatory effect of substance P in situ was blocked by gamma-aminobutyric acid (2-20 micrograms/kg) and the substance P antagonist [D-Arg1,D-Pro2,D-Trp7.9,Leu11]substance P (0.5-20 micrograms/kg) but was not altered by atropine (10-100 micrograms/kg), hexamethonium (0.5-2 mg/kg), norepinephrine (2-20 micrograms/kg), or leucine enkephalin (0.5-20 micrograms/kg). The bladder contractions elicited by substance P were not blocked by atropine, hexamethonium, or [D-Arg1,D-Pro2,D-Trp7.9,Leu11]substance P (0.1-10 micrograms/kg) but were blocked by another substance P antagonist, [D-Pro2,D-Phe7,D-Trp9]substance P. These data indicate that substance P has a direct postsynaptic excitatory effect on neurons in the vesical parasympathetic ganglia and on bladder smooth muscle cells. The differential effects of substance P antagonists on the excitatory responses at these two sites indicate the responses were mediated by different types of tachykinin receptors.

Animals↗
PubMed1983

Behavioral and central visual correlates of inherited retinal degeneration in the domestic chicken (Gallus domesticus).

A developmental, posthatch loss of cutaneous and ocular melanocytes in the mutant DAM (delayed amelanotic) chicken is accompanied by severe retinal degeneration. Using a food-location task, increased ocular pigment loss was associated with increased latency of response, both developmentally in young DAMS, and among adults with differing degrees of amelanosis. Analysis of optic nerve fiber composition in normals and DAMs showed a reduction in the small diameter optic axon population in severely amelanotic DAMs. With increasing severity of ocular amelanosis among animals, reduction in the density of anterogradely transported horseradish peroxidase (HRP) reaction product was seen first in retinorecipient thalamic nuclei, subsequently in the optic tectum, and ultimately in the accessory optic nucleus. An inverse relationship was also observed between the density of HRP reaction product occurring in retinal terminal fields and density of HRP label seen in the optic tracts of the same animal. No changes in either the volume or extent of central visual nuclei were apparent in partially sighted and blind DAMs.

Animals↗