Adaptive thermoregulation during summer in two populations of an arid-zone passerine.

Heterothermy plays an important role in lowering the costs of thermoregulation in endotherms by reducing water and energy requirements. We tested predictions that birds in arid habitats should express fine-scale variation in their thermoregulatory patterns as a function of prevailing climatic conditions. We assessed effects of air temperature (Tair) and water vapor pressure deficit (D) on body temperature (Tb) in free-living White-browed Sparrow-Weavers (Plocepasser mahali) during summer in two arid habitats in the Kalahari Desert, South Africa, using data from a dry period at a hot, desert site (n=7 birds), and during a dry period (n=4 birds) and a wet period (n=5 birds) at a milder, semi-desert site. The desert birds maintained a significantly higher set-point Tb (41.5 degrees+/-0.2 degrees C, mean-SD) than semi-desert birds (40.2 degrees+/-0.2 degrees C). During the warmest part of day (12:00-18:00 hours), Tb increased significantly during periods of high Tair and/or high humidity, and mean and maximum Tb were up to 1.40 and 2.3 degrees C, respectively, above normal levels. However, as Tair increased, birds at the desert site maintained Tb at or below set-point levels for a greater proportion of the time than birds at the semi-desert site. Birds at the desert site also expressed a greater magnitude of daily heterothermy (heterothermy index, HI=2.4 degrees+/-0.3 degrees C, mean+/-SD) than birds at the semi-desert site: the latter population showed a greater magnitude of heterothermy during a dry period (HI=2.1 degrees+/-0.3 degrees C) than during a wet period (HI=1.6 degrees+/-0.2 degrees C). Birds continued foraging throughout the warmest part of the day, despite the fact that heat dissipation (percentage of time spent panting and wing-spreading) increased significantly with increasing Tair. Our findings reveal that populations can vary in their thermoregulatory responses in both space and time and suggest that small changes in Tair can have significant effects on thermoregulation in free-ranging desert birds, even when Tair

Multifocality in the earliest detectable breast carcinomas.

A prospective study (protocol SG 89-150) was undertaken to determine the role of mammographically guided fine-needle aspirations in the diagnosis and subsequent surgical treatment of nonpalpable, mammographically detected breast cancers. During this study, once a diagnosis of cancer based on mammographically guided fine-needle aspiration was established, a wide segmental excision was performed to attempt to eradicate local disease. Surgical margins free of tumor were obtained in all cases. Total excision of these small lesions permitted in-depth histopathologic evaluation of the specimens. This led to the discovery that even the earliest detectable breast cancers may have extensive involvement of the surrounding breast tissue, which is vital information for planning complete therapy for the patient with breast cancer.

Mammogram-directed fine-needle aspiration of nonpalpable breast lesions.

A prospective study was undertaken to evaluate the effectiveness of mammogram directed fine-needle aspiration cytology in women with nonpalpable abnormalities detected on mammogram. Seventy patients were entered into the research protocol, with 61 patients undergoing mammogram directed fine-needle aspiration. Forty-three of the aspirates were adequate for diagnosis. Fine-needle aspiration yielded an accurate diagnosis in 12 of the 14 carcinomas in which the sample was considered adequate, for a sensitivity of 87%. No patients were falsely diagnosed with malignant disease, a specificity of 100%. The predictive value of a positive test was 100%, and that of a negative test was 93%. We conclude that fine-needle aspiration cytology can aid in making a diagnosis when nonpalpable breast abnormalities are detected on mammogram.

Use of paramagnetic chelated metal derivatives of polysaccharides and spin-labeled polysaccharides as contrast agents in magnetic resonance imaging.

Soluble and insoluble polysaccharides were derivatized with diethylenetriaminepentaacetic acid (DTPA) and/or spin-labeled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Polysaccharides derivatized with DTPA were prepared via cyanogen bromide activation, coupling to a diamine linker, and to DTPA anhydride. Spin-labeled polysaccharides were also prepared via cyanogen bromide activation. The extent of derivatization for dextran (18 kDa) was about 120 glucose units per DTPA, and for cellulose and starch about 15-30 units per DTPA. For spin-labeled polysaccharides, the average loading ranged from 1 nitroxide per 16 glucose units for starch to 181 for dextran (82 kDa). These derivatized paramagnetic polysaccharides were shown to be more effective relaxants than the small paramagnetic molecules alone. Both soluble and insoluble polysaccharide-linker-DTPA-Gd(III) complexes were effectively cleared from the body (rats) after oral administration. After intravenous administration, the biodistribution of dextran-linker-DTPA-Gd(III) complexes differed significantly from that of GdDTPA. Reduction of the nitroxide by ascorbic acid was retarded in the polysaccharide derivatives, particularly in starch derivatized with both nitroxide and linker-DTPA-Cu(II). These agents showed contrast enhancement in the gastrointestinal tract of rabbits.

Histiocytoid carcinoma: a variant of breast cancer.

The history of a patient presenting with metachronous bilateral breast cancer displaying histiocytoid features is reviewed. Although regional metastases were noted, this patient has not demonstrated an aggressive systemic disease pattern. In the past, histiocytoid breast cancer has been classified as either a lipid-rich carcinoma or as a variant of lobular carcinoma. However, histiocytoid carcinoma should be considered a distinct entity. Unlike the lipid-rich carcinomas, this tumor stained strongly for mucin. Immunoperoxidase staining indicated strong positively for CEA and negative staining for alpha-lactalbumin. There is suggestive evidence of a relationship between histiocytoid breast carcinoma and breast cancers of apocrine origin. Controversy remains and further evaluation is needed to elucidate the histiogenesis and biological potential of this neoplasm.