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Featured researches published by Paul D. Rosahn.


Experimental Biology and Medicine | 1933

Pathogenicity of Serratia Marcescens (Bacillus Prodigiosus)

Paul D. Rosahn; C. K. Hu

In connection with an investigation to determine the etiological agent responsible for a pandemic disease of rabbits 1 , filtration experiments were conducted, and all filter candles were tested in the usual manner with a strain of Serratia marcescens (Bacillus prodigiosus) obtained from Institute stocks. As the work progressed, a fortuitous observation led to an investigation of the pathogenicity of this organism. The growth from a 24 hour agar slant was suspended in 10 cc. of Lockes solution, and rabbits and mice were injected with this material. Rabbits receiving 0.3 cc. intra-cerebrally, or 1.0 cc. intraperitoneally, intravenously, or intrates-ticularly, all died within 24 hours, and all mice injected with 0.6 cc. intraperitoneally or 0.05 cc. intracerebrally also died within 24 hours. A benign course attended the use of smaller amounts of the organism. The gross findings at autopsy were striking. Hemorrhagic peritonitis with effusion, punctate hemorrhages in the adrenals, hemorrhagic lymph nodes, and small areas of focal necrosis in the liver were constant findings. An occasional animal had consolidated patches in the lungs. The spleen was usually large and swollen. Bacillus prodigiosus was recovered in pure culture from the brain, liver, spleen, lymph nodes, kidneys, lung, and blood. A second strain of the organism was obtained from another laboratory. Morphologically and culturally it was identical with our own strain. When injected into animals in the large doses previously mentioned, it too caused death in less than 24 hours, and the same pathological picture was present. Bertarelli 2 reported the death of rats, guinea pigs, and mice following the inoculation of massive doses of Bacillus prodigiosus.


Experimental Biology and Medicine | 1933

Experimental Transmission of Rabbit-Pox by a Filterable Virus

Louise Pearce; Paul D. Rosahn; C. K. Hu

Experimental transmission of the spontaneous rabbit-pox discussed in the preceding communication 1 was attempted early in the course of the pandemic. Since the result of bacteriological examinations together with the clinical picture of the condition made it appear unlikely that we were dealing with any of the usual bacterial agents, the initial experiments were carried out with Berkefeld “V” filtrates of various organs and tissues from rabbits showing well marked symptoms of the disease. In other experiments, unfiltered suspensions were used. The organs employed included: testicle, liver, spleen, lung, popliteal lymph nodes, brain, spinal cord, blood, and skin. Injections were made into the testicles of rabbits procured from outside sources. The results of the first experiments were positive in that an orchitis and scrotal edema were pronounced within 48 hours, fever developed (105°-107°), the animals appeared ill, frequently a diarrhea was present, and death occurred in from 4 to 8 days. This condition has been produced successively from rabbit to rabbit by means of filtered material (usually testicle) and the agent is now in the fifteenth serial passage. Other routes of inoculation have also been successfully employed, namely, intracutaneous, subcutaneous, intravenous, intraperitoneal, intramuscular, intracerebral, and nasal and conjunctival instillation. By using small doses and certain routes of inoculation, it has been possible to reproduce all the clinical and pathological features of the spontaneous disease including the characteristic pock eruption of the skin and mucous membranes. In addition, complete recovery has occurred in these circumstances. The agent is active in tissue stored in 50% glycerol at ice box temperature for at least 94 days. Unfiltered material is much more potent than that filtered through a Berkefeld “V” candle but an “N” filtrate is also active.


Experimental Biology and Medicine | 1935

Birth Weight Criterion of Dwarfism in the Rabbit

Paul D. Rosahn; Harry S. N. Greene

Conclusions When the birth weight of a rabbit as determined by the routine procedure described is less than 50.1 % of the weight of his heaviest littermate, a diagnosis of dwarfism is warranted. The birth weights of unusually small, nonviable animals derived from known transmitters of the abnormality fall below the 50.1% class, and these animals are, therefore, genetically true dwarfs in the sense that their abnormally low weights cannot be ascribed to environmental and nutritive factors operating in the interval between birth and the weight determination.


Experimental Biology and Medicine | 1934

Hereditary Variations in Litter-Size of Rabbits

Paul D. Rosahn; Harry S. N. Greene; C. K. Hu

An analysis of 569 pregnancies occurring in our breeding colony during the 5-year period from 1929 to 1933 has indicated the presence of wide variations in the mean gestation periods of different breeds. 1 These differences were attributed to hereditary factors. The present report is concerned with an analysis∗ of the size of the litters resulting from these 569 pregnancies, the particular purpose being to ascertain whether breed had any influence on litter-size. The pregnancies were the result of matings made in all months with the exception of July and August. Eleven breeds consisting of 10 standard bred strains and one intensely inbred line of albinos which may be considered as a breed or family are represented. The mean litter-size ranged from 3.92 for Polish rabbits to 7.14 for the Beveren and Flemish breeds. It was found that the variance between breeds was significantly greater than the variance within breeds (Var. between means of breeds = 40.43; Var. within breeds = 4.67; F = 8.65; P = 0.01—, significant). The demonstration of heterogeneity between breeds is interpreted as indicating that with respect to litter-size, each breed represented a homogeneous, normally distributed population. Certain environmental factors which might account for the breed differences were considered. All animals received the same diet and were housed indoors under uniform conditions. Seasonal factors at the time of mating did not influence the litter-size, since a significant difference was not noted between the mean values calculated from all matings in the 2 intervals from March to October, and from November to February (March to October: n = 295, Mn = 5.18 ± 0.14; November to February: n = 274, Mn = 5.47 ± 0.14, D = 0.29 ± 0.19, t = 1.5, not significant). Moreover, the variance within 2 months intervals was larger than the variance between 2 months intervals, although the difference was not significant (Var. between means of 2 months classes = 11.53; Var. within 2 months classes =5.30; F = 2.18, not significant). With respect to season therefore, the population appeared to be homogeneous.


Experimental Biology and Medicine | 1931

A New Capillary Hematocrit.

Paul D. Rosahn

The apparatus to be described is an accurate and inexpensive hematocrit of extremely simple construction, employing heparin as an anticoagulant. Values are expressed directly in per cent by measuring the column of packed blood cells with a millimeter scale. That readings are made directly is an obvious advantage over a somewhat similar hematocrit described by Epstein, 1 with which the readings are calculated by dividing the length of the column of cells by the length of the original column of blood, and multiplying the quotient by 100. The hematocrit here described is a pipette 12 cm. long, cut from selected glass tubing of uniform bore, having an outside diameter of 5 mm. and a bore of 0.5 to 0.8 mm. One end is beveled, and exactly 10 cm. from this end is engraved a circular mark. Before use the tube is lined with the anticoagulant by drawing an aqueous solution of 1/2 to 1% heparin through the pipette which is then allowed to dry. The tube is then sealed by encircling it with a rubber band No. 84 which is 9 cm. long and 1.3 cm. wide. No subsequent leakage occurs if this sized rubber band is placed securely around the pipette. A rubber mouth suction tube is attached to the unbeveled end of the hematocrit, and freshly flowing blood obtained by needle prick is drawn up to the circular mark. Blood adhering to the outside is wiped away, the suction tube is carefully removed, and the pipette encircled from end to end with the rubber band. The hematocrit is now placed in a centrifuge with beveled end down and rotated for 20 minutes at 3000 r.p.m. Centrifugalization at this rate for more than 20 minutes gives constant readings.


Experimental Biology and Medicine | 1931

Delayed Differential Counting of the White Blood Cells by a Modified Supravital Technique.

Albert E. Casey; Paul D. Rosahn

It is a common experience in doing differential white blood cell counts by the supravital method 1 , 2 that the cells cannot be identified after about 2 hours in the hot-box, since by this time nearly all the cells have taken up large amounts of the dye. It has been found that by a relatively slight modification of the usual technique, differential counts may be made with great facility as long as 12 to 24 hours after taking the blood. This has been accomplished (1) by reducing the concentration of the dye used, (2) by placing the blood smears in the refrigerator until ready for counting, and (3) by eliminating the hot-box. Through the use of this procedure, all cells have been found to be actively motile and to retain their morphological viable characteristics; a 24 hour preparation which has been kept in the icebox appears to be entirely similar to a fresh smear and cannot be distinguished from it. Thirty drops of a saturated solution of neutral red iodide No. 2 in 10 cc. of absolute alcohol is a satisfactory concentration for rabbits blood instead of the usual 50 to 100 drops; as much as 100 drops per 10 cc. of absolute alcohol has been used with success in the case of normal human blood. Smears left in the open laboratory were found to last about four hours or twice as long as those kept at 37° in the hot-box. Further reduction of the temperature to 5°-10° (refrigerator) effected the preservation of the cells for as long as 24 hours. When the preserved smears are examined with an ordinary electric bulb as the source of illumination, active motility of the white cells is evident.


Experimental Biology and Medicine | 1935

Serum phosphatase in normal young rabbits.

Paul D. Rosahn

Summary Within the age limits of 15 and 71 days the serum phosphatase values for healthy rabbits describe a statistically significant linear decrease with increasing age and weight.


Experimental Biology and Medicine | 1934

Reaction of the Rabbit to Vaccine Virus

Louise Pearce; Paul D. Rosahn; C. K. Hu

Little information is available regarding the clinical reaction of the rabbit to cutaneous inoculation of dermo-vaccine virus except as regards the local reaction at the site of injection. Furthermore, factors which presumably might affect the response as, for example, age, have not generally been considered. Our interest in the matter arose from the results obtained in the vaccination of the rabbits of a large breeding colony. The experiments are still in progress but enough has been learned to show that the clinical reaction of the rabbit to vaccination is extremely variable and that these variations are associated with a number of factors which concern the host. Approximately 1800 rabbits were vaccinated in December, 1933, and January, 1934, with culture dermo-vaccine virus obtained through the kindness of Dr. T. M. Rivers. The injections were made intracutaneously with dilutions ranging from 1:50 to 1:40,000. Previous tests had shown that the virus was active in a titre of 1:100,000 to 1:1,000,000 injected intradermally. Certain outstanding results of the experiments may be briefly summarized as follows. A typical local reaction developed in the adult non-immune stock of both sexes but it was much more severe in bucks than in does, and more pronounced in resting than in pregnant and nursing does. Generalized manifestations consisting in particular of a cutaneous maculo-papular eruption in areas remote from the injection site, as for example, the ears, were not infrequent. A lymph adenitis was also observed and an orchitis in male animals developed in many instances. There were a few cases of pronounced illness and prostration but only 3 fatalities. The results were quite different in the younger stock, all of which were presumably susceptible. In the first place, a local reaction did not develop in a large proportion of these rabbits and the incidence of negative results was inversely proportional to age.


Experimental Biology and Medicine | 1932

Comparison of the Blood Picture in Treated and Untreated Syphilis Patients

Paul D. Rosahn; Louise Pearce

Blood examinations were made on a number of syphilitic patients 20 who were divided into 2 groups. One group consisted of 58 patients who had received no treatment up to the time of the blood examination. Thirty-two were seen in the stage of an active primary infection, 18 had active secondary lesions, and 8 had signs and symptoms of tertiary disease. The second group consisted of 55 patients who had received varying amounts of specific treatment, ranging from less than one full course of arsphenamine and mercury to several such courses. In 20 of these, treatment was instituted during the primary stage of the disease, in 16 treatment was begun during the secondary stage, and in 19 during the tertiary stage. Since the patients were ambulatory and repeated counts could be obtained only with great difficulty, one complete blood examination was made on each individual. Each examination included a total red and white cell count made with standardized pipettes, a hemoglobin determination by the Newcomer method, a platelet count by the Ringer-heparin method of Casey, 1 , 2 and a differential white cell count made with the supravital technique, 100 cells being counted on each of 2 smears. The blood findings in these 2 groups were then compared, and the mean and standard error of the mean was determined for each blood element. A difference was considered to be significant when the probability of its occurrence by chance was less than one in 100. In the treated group as compared with the untreated patients, the hemoglobin level and the absolute and relative numbers of lymphocytes were significantly higher, while the total white cells, the number of platelets, the absolute and relative numbers of neutrophils, and the absolute and relative numbers of monocytes were significantly lower.


Experimental Biology and Medicine | 1934

Observations on vitamin treatment of reproductive abnormalities in the rabbit.

C. K. Hu; Paul D. Rosahn; Harry S. N. Greene

The reproductive activities of certain rabbits in our breeding colony have been observed on repeated occasions to be abnormal. These abnormalities may be classified, for present consideration, in 3 phases, namely, infertility, desertion or neglect of the young, and cannibalism. Observations indicated that some of these conditions were associated with nutritional disorders and it had been found that some improvement could be obtained by a general increase in vitamin intake. Accordingly, an attempt was made to correct the abnormalities of a selected series of animals by the administration of vitamin concentrates singly or in various combinations. The results thus far obtained have been highly encouraging and these form the basis of the present communication. A group of 42 rabbits was selected for this study. These included 38 females and 4 males of pure bred and hybrid stocks, chiefly Rex, Belgian hare, English, Havana, Dutch, Polish, Himalayan and a highly inbred Albino family. In each case previous observations had indicated that the reproductive behavior was abnormal. Following vitaminization for various periods of time, the treated animals were mated with known fertile animals and the results were measured by subsequent observations made with regard to the particular abnormality presented. In all cases except one, dried brewers yeast, representing the B complex was used either alone or in combination with halibut liver oil or viosterol or with both. Halibut liver oil alone was employed in one case. All vitamin concentrates were administered by hand. A few preliminary tests were made during the Winter of 1932-33 and the Spring of 1933, but most of the experiments were carried out between December, 1933, and February, 1934, inclusive. The test animals have lived indoors from birth and were distributed among normals in several rooms, and all the rabbits of the colony were fed a standard diet.

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C. K. Hu

Rockefeller University

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Albert E. Casey

Louisiana State University

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