Biomedical subjects

J A Andersen

Publications and source records attributed to J A Andersen.

At least 109 records · Page 6Linked to original sources

PubMed1978

Substrate, metal and template effects on inhibition of bacteriophage-qbeta ribonucleic acid polymerase by ortho- and pyro-phosphate.

Two reactions of bacteriophage-Qbeta RNA polymerase with synthetic templates were characterized and used to study the effects of substrate, metal and template on inhibition by Pi and PPi. Analysis of the poly(C)-dependent reaction yielded results on kinetics, GTP-dependence, preference for Mn2+ over Mg2+, and Michaelis constants for template similar to those in the literature. New data are provided for the poly(U2,C)-dependent reaction. Our results suggest that GTP and Mn2+ can form relatively stable complexes with the polymerase and that such complexes change the interaction of the enzyme with the inhibitors, Pi and PPi.

Coliphages↗

PubMed1977

Lobular carcinoma in situ of the breast. An approach to rational treatment.

A review of 3299 benign breast lesions was carried out. Lobular carcinoma in situ (LCIs) was discovered in 52 cases; and of these, 44 had been treated by biopsy alone. During the follow-up period averaging 15.9 years, 11 patients developed invasive breast cancer (IBC): 9 ipsilateral lesions, and 4 contralateral. This was about 12 times the frequency expected. The development of IBC had no relation to the patient's age, nor could any correlation be drawn between the time periods which elapsed from the time of the diagnosis of the in situ cancer to the development of IBC. The ipsilateral occurrence of IBC was not isgnificantly different from the contralateral. Careful lifelong follow-up seems to be the rational treatment for women whose breast biopsy shows LCIs.

Adult↗

PubMed1977

Focal pregnancy-like changes in the breast.

The aetiology of focal, preganancy-like mammary changes in non-pregnant and non-lactating women is discussed on the basis of the literature and a material of 31 patients. Such changes were found in one or more glandular lobules in 3 per cent of the breast tissue specimens received in our departments. As a rule, this finding was made in women who had been pregnant and who had been or were on oestrogenic or on contraceptive medication. They occurred in fertile, menopausal, as well as in post-menopausal women. Often they were seen many years after the pregnancy and/or intake of hormones. They were observed also in women who had never been pregnant or on hormone medication, and even in men on oestrogen therapy. It is likely, therefore, that focal pregnancy-like changes in non-pregnant and non-lactating women indicate a selective susceptibility of the mammary glandular tissue to oestrogen. Accordingly, we interpret the change as a normal histological variant.

Adenofibroma↗

PubMed1975

The basement membrane and lobular carcinoma in situ of the breast.

The basement membrane (BM) was examined by light microscopy in cases of lobular carcinoma in situ of the breast (LCIS), employing the following stains: haematoxylin-eosin, van Gieson-Hansen, PAS, colloidal-iron-PAS, and reticulin. The BM was non-intact in 12 out of 26 investigated cases of LCIS when reticulin staining was applied, but appeared non-intact in about 70 per cents with the other staining methods. On the other side control areas of the BM were intact in 23 out of 26 cases with reticulin stain, but in only about half of the cases with other stains. It is concluded that reticulin staining is the most suitable in evaluating the BM in LCIS, and that more or less pronounced defects of the BM in LCIS cannot be considered evidence of imminent invasion. Although the overall occurrence of invasive breast carcinoma was significantly increased in 9 cases with epithelial cell protrusion through the BM, this feature should be investigated further before it is allowed to affect therapeutic decisions.

Basement Membrane↗

PubMed1975

Benurestat, a urease inhibitor for the therapy of infected ureolysis.

A single oral administration of the urease inhibitor benurestat (2-(p-chlorobenz-amido)acetohydroxamic acid) to the human at 15 or 25 mg per kg produced, for 4 hr, mean urinary levels of inhibitory activity that were 700 to 1900 times that equivalent concentration of benurestat required to inhibit Proteus mirabilis urease by 90 per cent. In the rat these same dosage levels produced urinary inhibitory activity equivalent to 16 to 140 fold that required for 90 per cent urease inhibition. Benurestat administration, 25, 50, or 100 mg per kg, caused a decrease in the urinary excretion of ammonia from rats with experimental P. mirabilis genitourinary tract infection. The formation of struvite calculi was inhibited under these conditions. Nitrofurantoin, sulfamethoxazole, and ampicillin also slowed the formation of struvite calculi in infected rats and together with benurestat a potentiation of the inhibition of calculi formation was secured. Some combination therapies composed of benurestat plus an antibacterial agent, sulfamethoxazole or ampicillin, were effective in promoting the net dissolution of formed calculi. The number of viable bacteria present in the bladders of infected rats was significantly less after the administration of benurestat plus nitrofurantoin, sulfamethoxazole, or ampicillin than the respective numbers that were obtained from control infected rats or from rats administered either component of the combination separately.

Ammonia↗

PubMed1974