The in vitro development of innervated sensory hair cells of a mammal

Twelfth gestation day mouse embryo otocysts with their associated statoacoustic ganglions and otic mesenchyme were explanted to "in vitro". The otocyst explants developed for seven days in organ culture. They were then fixed and studied on a light microscopic and ultrastructural level for the development of synapses. Evidence is presented that strongly suggests that afferent synapses are developing "in vitro" in the vestibular sensory epithelium studied.     

Three-dimensional gray scale ultrasonographic imaging of the celiac axis: preliminary report

BACKGROUND AND OBJECTIVES: We have previously reported the isolation of a G protein-coupled receptor, CXCR-4, that is overexpressed in glioblastoma multiforme tumor tissue (GMTT), as compared to normal brain tissue (NBT). METHODS: Gene-specific RT-PCR, Northern blotting, and in situ hybridization techniques were used to study its expression in a variety of normal tissues, tumor tissues, and cell lines, as well as during development. Antisense CXCR-4 was overexpressed in glioblastoma cells to study its effect on cell proliferation. RESULTS: Gene-specific RT-PCR analysis indicated that the CXCR-4 gene is overexpressed in several malignant glioma tissues, breast tumor tissues and cell lines. Northern blot analysis indicated that CXCR-4 is expressed at high levels in certain leukemias, uterine cancer, and Burkitt's lymphoma cell line. The occipital and temporal lobe showed high levels of CXCR4 in normal human brain. The CXCR-4 gene was expressed in all organs in the early stages of development (days 8-10). In adult mouse, CXCR-4 is expressed only in brain, spinal cord, bone marrow, and pituitary gland. Antisense CXCR-4 overexpression in glioblastoma cells caused inhibition of cell proliferation and induction of cellular differentiation in vitro. This suggests that CXCR-4 expression may play an important role during embryonic development and also in the genesis of human gliomas. CONCLUSIONS: On the basis of CXCR4 expression data and antisense overexpression data, we conclude that CXCR-4 plays an important role in the tumorigenic properties of brain, breast, and other tumor types. On the basis of its unique expression during mouse development, we conclude that it may play an important role in the normal functioning of brain, spinal cord, and bone marrow during development.     

A simple but precise method for quantitative measurement of the quality of the laser focus in a scanning optical microscope

We report a method for characterizing the focussing laser beam exiting the objective in a laser scanning microscope. This method provides the size of the optical focus, the divergence of the beam, the ellipticity and the astigmatism. We use a microscopic‐scale knife edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide, and a light‐collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, a beam profile in the form of an error function can be obtained and by repeating this with the knife edge at different axial positions relative to the beam waist, the divergence and astigmatism of the postobjective laser beam can be obtained. The measured divergence can be used to quantify how much of the full numerical aperture of the lens is used in practice. We present data of the beam radius, beam divergence, ellipticity and astigmatism obtained with low (0.15, 0.7) and high (1.3) numerical aperture lenses and lasers commonly used in confocal and multiphoton laser scanning microscopy. Our knife‐edge method has several advantages over alternative knife‐edge methods used in microscopy including that the knife edge is easy to prepare, that the beam can be characterized also directly under a cover slip, as necessary to reduce spherical aberrations for objectives designed to be used with a cover slip, and it is suitable for use with commercial laser scanning microscopes where access to the laser beam can be limited.     

The Yugoslavia cardiovascular disease study. II. Factors in the incidence of coronary heart disease

In a 7-year follow-up of 11,121 Yugoslav men first examined in 1964-1965 when they were 35-62 years old, it was found that the incidence of coronary heart disease (CHD) was one-fourth that of a comparable Framingham (USA) group. Incidence in rural men was only 59% of urban men. In both urban and rural groups, men with higher blood pressures had greater CHD incidence, and cigarette smoking was also associated with greater incidence. In the urban but not the rural groups serum cholesterol and weight/height were also CHD risk factors. Levels of serum cholesterol and weight were lower in urban Yugoslavia than Framingham and lowest in rural Yugoslavia. At the same levels of these characteristics Framingham incidence was 3 times that in Yugoslavia. At the very low rural levels of weight and blood pressure CHD incidence was the same in urban as rural Yugoslav groups.     

Myxedema ascites

A 74-year-old man presented with mental obtundation and massive ascites without evidence of significant impairment of liver function. Thyroid function studies suggested hypothyroidism. Aspirated ascitic fluid had the characteristics of an exudate. Thyroid replacement therapy resulted in rapid clinical improvement with resolution of the ascites. Prompt recognition of myxedema ascites may prevent the inappropriate use of diuretic agents, therapeutic paracentesis, and sometimes unnecessary laparotomy.     

The tryptophan requirements of young laying pullets

Two experiments were conducted with laying pullets between 32 and 47 weeks of age. In each trial 1728 White Leghorn and 1728 cross-bred pullets were used. A series of diets of increasing protein content was offered. Protein quality was identical in all diets and tryptophan was demonstrated to be the most limiting amino acid in the protein mixture used. The daily tryptophan requirement of the individual pullet was estimated, by indirect methods, to be 2.25 mg/g egg output plus 10.25 mg/kg body weight. Response curves for flocks of pullets are illustrated. Calculated optimum intakes of tryptophan for various ratios of costs of input to value of output are tabulated. It is estimated that for a flock of mean body weight 1.5 kg, producing 55 g egg mass/hen d and consuming 110 g food/hen d, the optimum dietary tryptophan concentration is 1.7 g/kg when the marginal cost of supplying 1 kg tryptophan is 20 times the marginal value of 1 kg egg output.     

Medical technology and cost containment: two applications of operations research

The government proposes "common sense" regulations to help contain rising health costs due to the increasing use of high-technology procedures, such as computerized tomography scanning. Two illustrations are given showing that such ad hoc regulations may have the effect of increasing costs and are certainly far from the optimum obtained by known methods of operations research.