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Biomedical subjects

A Riesenfeld

Publications and source records attributed to A Riesenfeld.

14 recordsLinked to original sources
PubMed1991

Effects of perinatal alcohol exposure and dietary calcium supplements on skeletal and dental growth in rats.

Osteoporosis, hypocalcemia and skeletal size reduction are all common correlates of perinatal alcohol exposure. The present study assesses the effects of dietary calcium supplements on reversing perinatal alcohol-induced osteopenia. One hundred and twenty-nine offspring from Fisher 344 rats received 14% v/v alcohol in tap water from conception to weaning or 3 months of age followed by dietary calcium supplements (230 mg/kg/day) to 6 months of age. Significant group effects (p less than 0.001) were noted for all 12 dental and skeletal dimensions measured. Results suggest that calcium therapy following perinatal alcohol exposure may ameliorate alcohol-induced osteopenia in exposed offspring.

Alcohol Drinking↗
PubMed1988

Effects of nicotine on the fertility, cytology and life span of male rats.

Contrary to an earlier opinion that nicotine has no effect on the fertility of male animals or humans, the present experimental study using male inbred Fisher rats demonstrates that the reproductive capacity of the animals is greatly reduced when injected with nicotine, and that the effect is much greater in male than in female Fisher rats similarly injected with nicotine. This is in accord with some earlier histological and morphological studies which have shown that female rodents have a greater tolerance to nicotine than their male counterparts. It is also confirmed by the cytologic observations of the present study. These observations show that, similar to female rats, inflammatory processes, as evidenced by an increased number of lymphocytes and/or polymorphonuclear leukocytes, are responsible for the decrease in fertility. However, the cytological profile is profoundly different in the two sexes: virulent inflammatory conditions begin much earlier in male rats, they are more frequent and, whereas the condition is reversible in the female animal when nicotine treatment is discontinued, it is not in some male rats, and inflammatory conditions persist for the entire life as does infertility. However, the life span of nicotine-treated male rats is greater than in female nicotine-treated rats, although it is shorter in both sexes than in their respective controls; in some male nicotine-treated rats, the life span is greater not only than in their male controls but even than in their female counterparts. Possible explanations for this apparently paradoxical life-prolonging effect of nicotine treatment are reviewed, but the evidence is either conflicting or insufficiently established and requires further study.

Animals↗
PubMed1987

The effect of nicotine and alcohol on the fertility and life span of rats. A cytological analysis.

Inbred Fisher and Buffalo rats were exposed to nicotine and alcohol. Fertility was greatly reduced in both strains with nicotine treatments being much more deleterious than alcohol use. Fisher rats tolerated both toxins better than Buffalo rats. Both strains became 'extinct' after one generation of fetal and postnatal exposure to nicotine, but alcohol-ingesting Fisher rats had 3 or more generations of offspring. The total reproductive period was significantly shortened in both strains under the effect of both toxins, as was the total life span. The causes of the teratological effects of both toxins are inflammatory processes as evidenced by the presence of numerous lymphocytes and/or polymorphonuclear leukocytes. Their presence occurs earlier in nicotine than in alcohol use and earlier in Buffalo than in Fisher rats, but the damage done during nicotine treatment is reversible when the procedure is terminated. Inflammation is not transmitted to the newborn offspring of nicotine- or alcohol-treated mothers, but occurs in neonates during the nursing period or later. There is considerable individual variation in the tolerance to both toxins. Experimental results and clinical observations show a sufficient number of similarities to justify the use of experimental data as a model for further studies on human subjects.

Animals↗
PubMed1979

Vibrissae removal and the phenomenon of unexplained sudden death.

Two earlier theories on the effect of vibrissae removal in rats were tested. One theory stating that vibrissae removal produces impairment of spatial orientation capacity was confirmed. The other stating that it causes a depressive state of hopelessness and sudden death could not be confirmed. It is concluded that the extrapolation from the particular animal experiment to human psychological processes is not justified.

Animals↗
PubMed1979

Hybridization and heat tolerance in rats.

Buffalo and Fisher inbred rats and their F1--F4 hybrids were exposed to heat, 96 degrees F and 30% humidity, at 35 days of age. Fisher rats which are of lighter weight survive significantly longer than Buffalo rats which are heavier. Body weight was significantly depressed in all hybrids. Only in F2 hybrids was heat tolerance similar to that of the Fisher inbreds. In all other hybrids, it was lower. No heterosis was found under the conditions used.

Adaptation, Physiological↗
PubMed1978

Sexual dimorphism of skeletal robusticity in several mammalian orders.

This study tries to determine whether a phylogenetic trend exists in the sexual dimorphism of skeletal robusticity and whether domestication has an effect on it. The problems were studied in the metatarsals of marsupials, insectivores, rodents and primates including Homo, and in various skeletal sections of wild and domesticated rats and dogs. No clear phylogenetic trend could be found and domestication cannot be shown to have an effect on diminishing skeletal robusticity. Sexual dimorphism of skeletal robusticity seems to be highly species-specific and to have a mosaic distribution in a given taxon. Conclusions on phylogenetic trends of sexual dimorphism of skeletal robusticity and the effect of culture on it seem to be premature.

Animals↗
PubMed1978

Functional and hormonal control of pelvic width in the rat.

Absolute sacral dimensions of the rat are influenced by muscular, ovarian and testicular action, and all affect absolute sacral length more than absolute width. However, relative to trunk-length dimensions are rather stable and drop with a higher level of significance only in castration combined with estrogen or progesterone treatment. Relative pelvic width, as expressed by the transverse interiliac distance, is greatly widened in extreme muscular hypofunction but the sacrum does not participate in this widening. The widening results from a broadening of the proximal part of the ilium, following a genral response of long bones to extreme muscular hypofunction. Pelvic width is reduced in castration and ovariectomy with and without testosterone or estrogen treatment, but not in the combination of castration with progesterone treatment. Changes of sacral width are, however, more often independent from than concomitant with the width changes of the pelvis. The transverse interventral spine distance is dependent on rectus femoris muscle activity and drops drastically in hind-leg removal. It also drops in castration and particularly when castration is combined with estrogen treatment; but progesterone adds little to the effect of castration alone. The effect of ovariectomy alone or combined with testosterone treatment is negligible.

Amputation, Surgical↗
PubMed1977

Relationship between facial protrusion and tooth length in four strains of rats.

Total tooth length was measured in the first lower molar of two short-faced strains of rats (Sprague-Dawley and Buffalo) and two long-faced strains (BN and GRL). Tooth length was significantly longer in the long-faced than in the short-faced strains. The same correlation had previously been found in dogs, baboons and human populations, as well as in rats in which facial shortening was obtained experimentally by septum removal. The data suggest that the same mechanism is responsible for this relationship in all groups.

Animals↗
PubMed1977

Is the biomechanical principle of 'antagonistic compensation' valid also on the genetic level?

According to 'antagonistic compensation', appendicular bones rendered hypofunctional by surgical means, become shorter and more robust. In normal Buffalo rats, appendicular bones are short and very robust and in Fisher rats they are long and gracile. Total body constitution is robust in Buffalo rats and gracile in Fisher rats. In GRL rats, appendicular bones are short but body constitution is gracile and the robusticity of the appendicular bones is intermediate between Fischer and Buffalo rats. Thus, total body constitution and relative length of the appendicular bones determine their robusticity, shorter bones being more robust than longer bones. In other words, the relationship between bone length and robusticity is the same in experimentally produced antagonistic compensation and genetically determined normal condition of rats.

Animals↗
PubMed1977

Sexual dimorphism of bone robusticity in different strains of rats.

A quantitative method was used to establish the sexual dimorphism of bone robusticity in 10 domesticated strains of rats and in wild rats. Sexual dimorphism had its highest frequency in the pelvis, followed by the ulna, the skull, and the femur and tibia. Humerus and tail showed the lowest frequency of such sexual dimorphism. This distribution in an unspecialized mammal such as the rat, in which selective pressures are at their minimum becauses of the factor of domestication, can serve as a baseline for comparison with taxa in which selective forces are more strongly active.

Animals↗
PubMed1976

Compact bone changes in cold-exposed rats.

Rats exposed to cold stress show a reduction of relative cortical thickness in their long bones. The reaction resembles reduction of cortical thickness observed in Asiatic humans of the Mongoloid race, in whom many morphological features have been postulated to be cold-adaptive. However, until it can be established that the physiological processes underlying the experimental and phylogenetic condition are similar, no extrapolation can be attempted from the one to the other.

Acclimatization↗
PubMed1976

Constitution and body proportions in different strains of rats. A study of race formation in breeding isolates.

(1) There are considerable differences in body constitution in different strains of rats, ranging from very robust to very gracile forms. The differences are greater in the larger males than in the smaller females. (2)Craniofacial and postcranial proportions of the trunk in domesticated strains of rats differ either uniformly or mosaically from the wild form. (3)Nasal shape differs greatly in rats ranging from extreme leptorrhine to extreme platyrrhine forms, giving a total range greater than in human populations. (4)Fisher 344 rats have long tails and extremities and Buffalo and GRL short tails and extremities. (5)Wistar and ACI rats have longer tails than wild rats but do not differ significantly from wild rats in the relative length of their other extremities. (6)The relationship between tail and extremity length is under genetic control which is concordant in Fisher, Buffalo and GRL rats, but discordant in the Lewis, Wistar and ACI strains. (7)There is no connection between relative extremity length and total body constitution since short-limbed strains occupy both the highest (Buffalo) and lowest (GRL) levels o f robusticity, and strains that do not differ in relative extremity length from wild rats differ greatly from each other in constitutional type (Wistar and ACI). (8)Differences of relative extremity length and nasal shape in rats have their parallels in human populations. But in human populations they follow Allen's ecological "rule" and can be duplicated experimentally. In rats here used, however, they do not result from any known ecological pressures, but from the genetic factors acting in breeding isolates.

Animals↗
PubMed1975

Endocrine control of skeletal robusticity.

Changes of skeletal robusticity result from a mosaic response of various parts of the skeleton to given endocrine changes. The character of these reactions corresponds to that of muscles which act as selective target areas for specific hormones. Robusticity changes are mediated by increases or decreases of the length and weight of the bones. The changes are probably species- or even subspecies-specific.

Animals↗