Showing papers by "University of Louisville published in 1969"

Flow Through Collapsible Tubes and Through in Situ Veins

Abstract: The flow of blood in veins differs from the flow of liquids in rigid, circular tubes in that veins are collapsible vessels. Studies in models employing thin-walled rubber tubes and in the intact animal have shown that the flow (ml/s) of liquid through such a collapsible tube, in which the pressure immediately downstream to the collapsed segment is less than the pressure surrounding the collapsed segment, is unaffected by changes in the downstream pressure. With changes in the downstream pressure the collapsed tube automatically adjusts its resistance so that flow remains constant. In the mammalian organism the flow of blood in veins above heart level, and at the points where veins enter the low pressure area of the thorax, is governed by the principles of flow through collapsible tubes. The importance of the collapse phenomena in the flow of blood through the lung and other organs is discussed. Flow through such tubes is a special case of Bernoulli's theorem for the flow of viscous liquids, and under certain circumstances it is described with a reasonable degree of accuracy by a modification of the Hagen-Poiseuille law for tubes of elliptical cross section.

High-affinity binding of progesterone, testosterone and cortisol in normal and androgen-treated guinea pigs during various reproductive stages: relationship to masculinization.

Abstract: Sera from normal and androgen-treated female guinea pigs were obtained during the estrous cycle, pregnancy and puerperium. They were analyzed for binding affinity toward progesterone, testosterone and cortisol by multiple equilibrium dialysis using radiolabeled steroids. Cortisol levels were also determined. A marked increase in binding activity for all 3 steroids, especially progesterone and testosterone, was found during pregnancy; the cortisol concentration rose concomitantly. By the end of the puerperium all parameters measured had returned toward estrous cycle levels. Testosterone treatment of the cycling females greatly lowered the cortisol-binding activity of the serum as well as the peripheral cortisol values, and resulted in a slight decrease of the binding activity for testosterone. Sera from pregnant guinea pigs receiving testosterone had lower peripheral cortisol levels than the pregnant controls; the binding activity toward progesterone and testosterone was generally greater than in the untre...

Inhibition of Protease Production of Various Bacteria by Ammonium Salts: Its Effect on Toxin Production and Virulence

Abstract: Production of protease by many bacteria was found to be inhibited by ammonium salts, and the enzyme production was more sensitive to the salts than was growth of the organisms. Inhibition of protease production by some pathogenic bacteria may result in the recognition of an exotoxin which otherwise would have been digested by the protease. In the case of Pseudomonas aeruginosa, qualitatively different toxicities could be demonstrated in the culture fluids, depending on the presence or absence of protease in such a fluid. The toxicity of the culture in the presence of a high titer of protease may be due primarily to the protease, whereas the toxicity exhibited in the absence of protease could be due to proteinacious exotoxin. Producers of high titers of protease tended to be less virulent in vivo than producers of low titers of the enzyme, which exert their toxicities by a separate exotoxin.

Changes in somatic antigens of Pseudomonas aeruginosa induced by bacteriophages.

Abstract: For at least 50 years, the somatic antigens of Pseudomonas aeruginosa have been widely studied [1-5], and more than 10 serotypes have been recognized on the basis of heat-stable antigens alone. In the United States, the antigenic schema most commonly accepted is the one established by Verder and Evans [5]; in Europe, that of Habs [6] appears to be the best known. The relationship between these 2 systems has been clarified by Muraschi et al. [7]. Most studies of somatic antigens were conducted as a means of recognizing types within the species for use in epidemiological surveys. Serotypes may be important from the viewpoint of immunological protection against the infections, since immunity is type-specific [8]. The bacteriophages of P. aeruginosa have been employed in epidemiological surveys [2, 9, 10]. Plaques of P. aeruginosa produced by phage action contain mutants which develop rapidly and often exhibit characteristics quite dissimilar to those possessed by the original strains. A survey of various strains of P. aeruginosa has therefore been conducted to determine the extent of changes in the somatic antigens induced by bacteriophages.

Biological inactivation of progesterone by interaction with corticosteroid-binding globulin and with albumin.

Abstract: Addition of a rat CBG preparation to a progesterone solution abolished the effect of the hormone on the ligated uterus of the ovariectomized mouse. Inactivation was also observed when rat serum albumin was used as the progesterone-binding protein. These results seem to show that the biological activity of progesterone is suppressed by complex formation with CBG or with serum albumin. (Endocrinology 85: 778, 1969)

Rayleigh scattering from leaves

Abstract: The effective dielectric constant, conductivity, and skin depth of an inhomogeneous medium consisting of uniformly distributed and randomly oriented Rayleigh region leaves is developed. Numerical calculations of these parameters for a frequency range from 30 to 300 MHz, leaf water contents from 10 to 50 percent and leaf volume concentrations from 0.03 to 0.1 percent are made.

Micropuncture and microperfusion study of L-glucose secretion in rat kidney.

Abstract: Studies with the free flow micropuncture technique have shown that the ratio of TF/Pl-glucose to TF/PInulin in proximal tubular fluid, in distal tubular fluid, and in more than half of the final urine samples measured was greater than one, which suggests thatl-glucose was actively secreted. Studies with the microperfusion technique confirmed this finding and showed thatl-glucose was secreted by the proximal tubules. A maximum rate of secretion was reached at a plasma concentration of 4 mM. The tubular secretion ofl-glucose was augmented by the presence of 16.6 mMd-glucose in tubular lumen and inhibited by 10−4 M phlorizin. Kinetic analysis showed that theV max values forl-glucose secretion in the absence and in the presence ofd-glucose are 5.0×10−10 and 6.3×10−10 mol×cm−2×sec−1 respectively which were very close to the value reported for theV max ford-glucose reabsorption. However, theK m forl-glucose secretion was 3.1 mM and was reduced to 1.6 mM whend-glucose was present in the perfusion fluid. TheK m ford-glucose reabsorption has been reported to be 0.6 mM (8). The results of this investigation were interpreted as being consistant with the hypothesis thatl-glucose secretion andd-glucose reabsorption share the same carrier system.

Control of cervix cancer in women of low income in a community

Abstract: A program to control cancer of the uterine cervix in women of a low‐income level in Louisville (Jefferson County), Kentucky over a 12‐year period is described. Initial satisfactory examinations were obtained on 37,209 women. Rescreenings at an interval of 1 to 12 years totaled 51,063 examinations. The population was equally divided between Negroes and Caucasians. Prevalence rates of cytologically detected cervix carcinoma were very high—3.79 per 1000 for invasive squamous carcinoma and 4.41 for carcinoma in situ. The first repeat examination based on patient years fell to 0.67 and 1.46 per 1000 women for these 2 lesions. The decrease continued through subsequent screenings. Stage I carcinoma increased to 63.93% of the total cases during the years of screening. We conclude from the data presented that mortality rates from cervix cancer will have to reflect the decrease in incidence and the increase in early diagnosed cases.

Experimental allergic uveitis III. Manifestations produced in the guinea pig by immunization with homologous retina

Abstract: Following one injection of guinea pigs with 10 mg. homologous retina in adjuvant emulsion, the large majority developed uveitis within 3 weeks. The clinical signs and histological manifestations observed at onset and for several weeks thereafter, during which the disease progressed from an iridocyclitis to cyclitis and choroiditis, are described. The development of cytologic events in the uveal tract resembled those of delayed hypersemitivity, in which lymphocytes predominated in the early infiltrate and plasma cells in the subsequent infiltrate. Although morphologic alteration of the retina was observed in some animals, it did not occur until after there was extensive cellular infiltration of the choroid. The possible relationship of this model to that produced previously with uveal tissue is discussed.

Gene Products of Amphiuma: An Amphibian with an Excessive Amount of DNA

Abstract: The nuclei of Amphiuma contain 168 pg of DNA, 28 times that contained in human nuclei. Although many higher organisms appear to possess an excessive amount of DNA, in Amphiuma this has been carried to the extreme. Studies of this organism thus may provide some insight into how this excess DNA is used. This organism presumably evolved by numerous polyploidy and gene duplication events. Do its gene products present multiple electrophoretic forms? Are they quantitatively increased to the same degree as the DNA? Electrophoresis of Amphiuma glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, acid phosphatase, lactic dehydrogenase, and hemoglobin failed to show any evidence for multiple electrophoretic forms of these respective gene products. The amount of hemoglobin, G6PD, and 6PGD per red cell was increased to a comparable or even greater degree than the DNA. Analytical ultracentrifugation demonstrated a satellite band of DNA with a density of 1.720 corresponding to a GC content of 61%. This probably represents DNA coding for ribosomal RNA. Electron microscopy of liver nuclei showed a significant amount of condensed chromatin. The implications of these observations are discussed.

Oxygen consumption, body temperature, and brown adipose tissue in the postnatal golden hamster (Mesocricetus auratus).

Abstract: Postnatal hamsters were examined for a metabolic response to cold by measuring oxygen consumption at ambient temperatures of 25°, 30°, 33°, and 36°C. In conjunction with this, colonic temperatures were recorded, and the animals were examined for brown adipose tissue development. During the first ten days of postnatal development hamsters increased their O2 consumption linearly as ambient temperature was raised from 25° to 36°C. Thus, they are initially poikilothermic. Body temperatures were directly dependent on environmental temperature, and no mature brown fat deposits had yet developed. On days 11 and 12, O2 consumption curves began to vary from a linear relation with ambient temperature, and small inflexions developed at 30° and 33°C. By postnatal days 14 and 15 maximal values were recorded at 25°C. Simultaneously, brown fat deposits developed definitive characteristics and body temperatures came to range only slightly below adult temperatures during exposure at 25°C. During the latter stage of maturation studied in these experiments, days 17 to 21, the animals achieved homeothermic stability between 25° and 36°C. Only 25°C prompted a metabolic increase, 30° to 36°C became a zone of thermal neutrality, and body temperatures came to equal or exceed adult temperatures. The animals had gained significant weight, thereby increasing thermal insulation, and brown fat deposits had accumulated additional lipid.

Relationship between EEG Activation and Reaction Time

Abstract: The relationship between RT and EEG activation, as defined by measurements of both amplitude and frequency (period) of waves from the dominant hemisphere, was investigated. A 250-c/sec. tone that was presented without a preparatory warning signal was the stimulus. Within-subject correlations from 99 Ss supported the hypothesis of an association between EEG activation and behavioral arousal. Frequency of the waves was a better predictor of RT than amplitude.

The genetic‐determination of ossification sequence polymorphism

Abstract: Serial hand-wrist x-rays of 81 pairs of twins were examined to investigate the genetics of ossification sequence polymorphism. Discordance in ossification sequence was 3.5 times more common between like-sex dizygotic twins than between monozygotic twins, with the difference being significant at the 0.01 level of confidence. These findings support the contention that the major part of variation in ossification sequence is genetically determined.

Control of responding by the elements of a compound discriminative stimulus and by the elements as individual discriminative stimuli.

Abstract: In the first of two studies, the responding of four albino rats was differentially reinforced in the presence of noise and light together and then tested in the presence of the noise and the light separately during extinction. The light exercised substantially more control of responding than did the noise. In the second study the responding of a similar group of four rats was differentially reinforced in the presence of the noise and the light separately. Control of responding by the light developed more rapidly than control by the noise. Results suggest that levels of control by stimuli after differential reinforcement with respect to the stimuli together can be predicted by the rates of development of control during differential reinforcement with respect to the stimuli separately.

Prognosis of breast cancer based on pathologic type.

Abstract: The pathologic type is of primary importance in determining the prognosis of operable breast cancer. The classification of Foote and Stewart or the slightly modified World Health Organization classification is recommended for general use so that comparative data between different series in various countries will be more meaningful. In view of the importance of the level of lymph node involvement in the axilla in primarily operable breast cancer, all surgeons are urged to avail themselves of this easily provided and highly significant bit of information.

A Confirmation of Electrogenicity of Frog Gastric Mucosa by Using Methoxyflurane

Abstract: ConclusionMethoxyflurane, like dinitrophenol, acts only on the H+ secretory mechanism in Cl--free solutions. This anesthetic also reveals the linear relationship between the PD and H+ rate and permits estimates of the parameters of the H+ secretory mechanism in Cl--free solutions.