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Biomedical subjects

A G Jabara

Publications and source records attributed to A G Jabara.

At least 19 recordsLinked to original sources
PubMed1989

A primary extraskeletal osteogenic sarcoma arising in the spleen of a dog.

This paper describes a primary extraskeletal osteogenic sarcoma arising in the spleen of an 11-year-old, male, cross-bred Terrier. Initial diagnosis was made after surgical removal of a splenic mass, at which time the liver and other abdominal viscera appeared grossly normal. However, elevations in the activities of alanine aminotransferase and alkaline phosphatase in blood taken 7 days after laparotomy suggested that hepatic metastases were developing. This was confirmed when the dog died 3.5 months after surgery, with massive hepatic metastatic involvement. There appears to be no previous report of the spleen being the primary site of such a neoplasm in the dog.

Animals↗
PubMed1984

A congenital vascular naevus in a foal.

This paper describes a case of a congenital vascular malformation in the skin of a colt. The lesion arose at the coronary border of the right hind leg. The microscopic structure of a biopsy suggested that the lesion, consisting of multiple foci of closely-packed convoluted small vessels in the dermis, represented a marked exaggeration of glomi which normally occur in considerable numbers in this region of the skin. On the basis of the clinical, macroscopic and histological findings, this lesion was considered to be an hamartoma, rather than a true tumour, and was therefore termed a congenital vascular naevus. The foal is remaining under observation to determine the eventual outcome of the lesion.

Animals↗
PubMed1984

Extraskeletal osteoma in a cat.

This paper describes a case of a benign osseous lesion which arose in the right front leg of an 8-year-old spayed female cat. The growth was situated in the dermal tissue above the olecranon, but not attached to it, and shelled out easily at surgery. While certain non-neoplastic lesions, such as hamartomas or cases of heterotopic ossification, may appear histologically similar, the present case was considered to be a true tumour on the basis of the clinical, macroscopic and histological findings, and was termed an osteoma. The cat is remaining under observation, but there had been no recurrence 3 1/2 months after surgery.

Animals↗
PubMed1982

Effects of progesterone on mammary carcinogenesis when various doses of DMBA were applied directly to rat mammae.

To investigate the suggestion that progesterone acts directly on the mammary gland to inhibit carcinogenesis, doses of 500, 100 or 30 microgram of DMBA were applied directly to inguinal mammary glands of 50 d old rats which either received no other treatment or were injected with progesterone (3 mg/d) s.c. for 18 d before dusting the carcinogen. Progesterone pretreatment did not inhibit mammary carcinogenesis in rats dusted with 500 microgram or DMBA. When smaller doses of DMBA (100 microgram or less) were applied, hormone pretreatment markedly reduced carcinogenesis, the inhibitory effect being statistically significant in the group dusted with the smallest dose of carcinogen. As the dusting technique eliminated any observable systemic effects of the carcinogen, it is concluded that the results support the suggestion that progesterone acts directly on the mammary gland to inhibit carcinogenesis and that this effect can be over-ridden if a large enough dose of DMBA (somewhere between 100 and 500 micrograms) is applied. The importance of carcinogen dose to resulting tumour yield was clearly shown by the significant descending gradation in tumour incidences and gradual lengthening of average tumour latent periods in the 3 control groups with decreasing DMBA dose, as well as in the 3 hormone-pretreated groups.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

Hormone and drug effects on growth of DMBA mammary tumours and plasma prolactin levels in adreno-ovariectomized rats.

The effects of hormone and drug treatments on plasma prolactin (PRL) levels and mammary tumour growth were investigated in rats bearing continuously growing DMBA-induced mammary tumours that responded to bilateral adreno-ovariectomy (Ax + Ox), Oestrogen (E2) administration increased both plasma PRL and tumour growth, but was unable to sustain tumour growth when the PRL level was reduced by concurrent injection of ergocornine (Eg). Perphenazine (Pz) produced a dose-related increase in plasma PRL, but stimulation of tumour growth in the absence of E2 required a minimal level of plasma PRL induced by Pz (0.15 mg/100 g body wt/day or more). Progesterone (P) (3 mg/day) alone, although without effect on PRL levels, maintained static tumour growth (i.e. it had a slight stimulatory effect) irrespective of the duration of treatment. The increase in plasma PRL levels above the basal values in the Ax + Ox controls following injections of combined P + Pz (0.1 mg/100 g/day) was sufficient to sustain static tumour growth, but not to reactivate growth. Enhancement of both plasma PRL and tumour growth did not occur until P and higher doses of Pz (0.3 mg/100 g/day) were injected jointly; this treatment, however, while unable to stimulate continuous tumour growth, was able to maintain static growth when plasma PRL was reduced by concurrent injections of P + Pz + Eg. From these findings it is postulated that the mechanism of action whereby P maintains static tumour growth is different from that of PRL and independent of circulating PRL levels.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

Effects of progesterone on mammary carcinogenesis by DMBA applied directly to rat mammae.

The effects and site(s) of action of progesterone on DMBA mammary carcinogenesis in the rat, when a small dose of the carcinogen was applied directly to the inguinal mammary gland, were investigated. No reduction in tumour yield was apparent when progesterone was administered s.c. for 18 days before dusting DMBA. This finding contrasts with a previously reported inhibitory effect on carcinogenesis when hormone treatment was followed by intragastric administration of DMBA. When progesterone injections were begun either 2 days before or 2 days after direct application of DMBA, and were continued until the end of the experiment (135 or 195 days) an enhancement in carcinogenesis was observed similar to that previously demonstrated after gastric intubation of DMBA. These findings, together with previously reported observations, suggest that progesterone may exert its inhibitory effect on carcinogenesis by acting at a site outside the breast, perhaps on the liver. However, it is likely that the hormone acts directly on the mammary tissue to exert its enhancing effect on tumorigenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

A mixed tumour and an adenoma both of ceruminous gland origin in a dog.

Ceruminous gland tumours are uncommon in the dog and this paper reports a case of two such tumours which arose in either ear of a 12 year old male long-haired Dachshund. Histologically, one tumour was a ceruminous adenoma and the other a rare ceruminous mixed tumour of borderline malignancy.

Adenoma↗
PubMed1975

Effects of 7,12-dimethylbenz(a)anthracene on rat mammary epithelial cell macromolecules: a time study.

The effects of 7,12-dimethylbenz[a]anthracene (DMBA) on levels of four mammary epithelial cell macromolecules were investigated at various times between 1 and 14 days after Sprague-Dawley virgin female rats were fed the carcinogen. Whereas the level of nuclear protein remained relatively constant throughout this period, comparison with normal controls revealed that significant reductions in nuclear RNA and cytosol protein levels occurred in cells from DMBA-treated animals 24 hours after carcinogen treatment; levels were lowest within the first 3 days. Cytosol protein and nuclear RNA values then increased progressively, reaching normal levels between 4 and 6 days; they were elevated 122% (+/-6 SD) and 41% (+/-5), respectively, above controls by the 14th day. DNA levels remained within normal limits up to the 4th day, after which they gradually increased to 36% (+/-5) above normal by the 14th day. All four macromolecules in neoplastic epithelial cells derived from three mammary adenocarcinomas approximately 135 days after DMBA was fed to rats showed increases similar to, though more pronounced than, those seen in mammary epithelial cells 14 days after carcinogen administration, which suggested that early changes in these macromolecules, especially in RNA and cytosol protein, may be related to DMBA mammary carcinogenesis. The data further suggested that malignant transformation of the epithelial cells may occur within the first 4-6 days, after which there appears to be a loss of normal synthetic control of nuclear DNA, RNA, and cytosol protein.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1973

Effects of hypothyroidism and progesterone on mammary tumours induced by 7,12-dimethylbenz(a)anthracene in Sprague-Dawley rats.

Hypothyroidism, alone or combined with progesterone, significantly decreased 7,12-dimethylbenz(a)anthracene (DMBA) mammary tumorigenesis relative to controls. However, the decrease was less in the progesterone-treated group, and statistical analysis showed that progesterone enhanced tumorigenesis to the same extent in hypothyroid animals as in the controls. Most tumours in hypothyroid progesterone-treated rats were adenocarcinomata; in the absence of the hormone most tumours were benign. However, the difference between the tumour types in the 2 groups was not statistically significant.The morphological changes observed in the endocrine glands, genital tracts and non-neoplastic mammary tissue, considered in relation to previously reported data, suggest that hypothyroidism reduced the tumour yield mainly by secondarily inhibiting somatotrophin production and secretion, although the effect of decreased food intake could not be excluded completely. The higher tumour yield in the hypothyroid progesterone-treated rats may have been due to higher circulating levels of prolactin in this group compared with those in the hypothyroid group which received no hormone.

Adenocarcinoma↗
PubMed1973

Effects of time and duration of progesterone administration on mammary tumours induced by 7,12-dimethylbenz(a)anthracene in Sprague-Dawley rats.

A reduction in tumour yield was apparent when progesterone administration was begun 25 days before feeding 7,12-dimethylbenz(a)anthracene (DMBA). This effect was most obvious when the duration of hormone administration was brief. Continuation of progesterone for some time after feeding DMBA caused a progressive diminution of the inhibitory effect, and 135 days of continuous hormone treatment entirely abolished the effects of 25 days pretreatment with the hormone.In contrast, when progesterone injections were begun 2 days after feeding DMBA, there was a trend towards enhancement of tumour yield. Continuous hormone administration appeared more effective than shorter treatment regimens.

Animals↗
PubMed1972

An autoradiographic study of the early effects of 7,12-dimethylbenz(a)anthracene and progesterone on DNA synthesis in rat mammary epithelial cells and subsequent tumour development.

Experiments were undertaken to investigate the early effects of DMBA or progesterone, or the two in combination, on DNA synthesis in rat mammary epithelial cells, and also to determine whether there was any correlation between the level of DNA synthesis observed in the first 96 hours after administration of DMBA, either alone or combined with progesterone, and subsequent tumour development.It was found that DMBA alone caused an insignificant reduction in DNA synthesis in the first 96 hours, whereas progesterone significantly enhanced DNA synthesis. When the carcinogen and hormone were administered together, a greater rise was seen in the level of DNA synthesis than that occurring in rats treated only with DMBA, but the increase was not significantly greater than that in untreated animals. A two-way analysis of variance revealed no interaction between DMBA and progesterone in relation to mammary epithelial cell DNA synthesis.Mammary neoplasms occurred only in the groups of rats which had received DMBA, either alone or in combination with progesterone. No correlation could be demonstrated between the extent of DNA synthesis observed in mammary glands biopsied between 6 and 96 hours after carcinogen administration and the occurrence of tumours in the host rats 135 days later.

Adenoma↗