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Biomedical subjects

F Kobayashi

Publications and source records attributed to F Kobayashi.

At least 181 records · Page 10Linked to original sources
PubMed1981

[The control of prolactin surge by ovarian steroids in the early phase of pseudopregnancy in rats (author's transl)].

The secretory patterns of prolactin and progesterone and the participation of ovarian steroids for their secretion in the early phases of delayed-pseudopregnancy (D-PSP) were studied in rats. D-DSP or immediate pseudopregnancy (I-PSP) was induced by vaginal stimulation (VS) given at 14:00 on diestrus 2. Blood for prolactin and progesterone analyses was obtained by decapitation performed every 2 hours between 13:00 on diestrus 2 and 13:00 on proestrus of the estrous cycle and during the corresponding stages of PSP. After the VS given on diestrus 2, concentrations of plasma prolactin and progesterone in D-PSP rats were the same as those of normal cyclic rats. In the rats given VS on estrus (Day 0) to produce I-PSP, a nocturnal surge of prolactin was obvious in the morning of Day 3. Plasma progesterone levels were also high in these rats. However, in the ovariectomized-adrenalectomized (OVX-ADX) rats, on which the operation was performed at various stages of the estrous cycle, a nocturnal surge of prolactin was clearly observed after the VS given at 14:00 on diestrus 2. The appearance of a nocturnal prolactin surge by the VS in the OVX-ADX rats was inhibited by the administration of estradiol-17 beta (1 microgram/rat). The nocturnal surge of prolactin in the early phase of I-PSP was also diminished by the administration of the steroid. Concomitant administration of progesterone with estrogen, however, overcame the inhibition of the nocturnal surge of prolactin by estrogen. These results indicate that the stabbing secretion of prolactin observed in the early phases of pregnancy or pseudopregnancy is modulated by the ovarian steroids and also suggests that the increasing secretion of estrogen from diestrus 2 to proestrus in the normal estrous cycle suppresses the prolactin surge expected by VS and resulting in D-PSP.

Animals↗
PubMed1981

[General pharmacological studies on a new macrolide antibiotic, miokamycin (MOM). 1. Effects on the central nervous system (author's transl)].

Behavioral and electroencephalographic (EEG) effects on a new macrolide antibiotic miokamycin (MOM), 9,3"-diacetylmidecamycin, were investigated in mice, rats and rabbits after oral administration. MOM caused a decrease in the spontaneous motor activity, a slight increase in the effect of megibal seizure at a dose of 1,000 mg (Potency)/kg, and an increase in the number of deaths on the maximal electroshock seizure after administration of doses more than 100 mg (Potency)/kg. Even at a dose of 1,000 mg (Potency)/kg, however, MOM showed no effects on general behavior, rectal temperature, traction test, inclined screen test, rotarod performance, thiopental-induced sleep, pentetrazol seizure, fighting behavior induced by electric stimulation and conditioned avoidance response. EEG effects in unanesthetized rabbits with permanent electrode implants were studied. MOM showed no effects on spontaneous EEG, arousal response to mesencephalic reticular stimulation, photic driving response, evoked cortical response by ventralis posterolateralis stimulation and afterdischarge elicited by hippocampal stimulation at a dose of 1,000 mg (Potency)/kg. Consequently, it can be concluded that MOM has no specific pharmacological effects on the central nervous system. Behavior effects of MOM metabolisms, Mb-1, Mb-2, Mb-6 an Mb-12, were almost the same as those of MOM in the mode of action.

Administration, Oral↗
PubMed1980

In vitro and in vivo antimicrobial activities of sporaricin A, a new aminoglycoside.

The in vitro and in vivo antimicrobial activity of sporaricin A, a new aminoglycoside, was compared with that of amikacin, dibekacin, and gentamicin. Sporaricin A showed a broad spectrum of activity against various gram-positive and -negative bacteria, including amikacin-, dibekacin-, or gentamicin-resistant strains. Sporaricin A inhibited more than 90% of clinical isolates of staphylococci, Klebsiella, Enterobacter, Citrobacter, Serratia, and Proteus, except for P. morganii and P. inconstans, at the concentration of 3.13 microgram/ml. This activity, except for that against Serratia, was similar to that of amikacin. Against P. inconstans and S. marcescens, sporaricin A was more effective than amikacin, dibekacin, and gentamicin. However, its activity against Pseudomonas aeruginosa was relatively weak in comparison with three other aminoglycosides. Sporaricin A was highly effective against bacteria that had various aminoglycoside-inactivating enzymes and that were resistant to the other drugs tested, but it was not active against those with aminoglycoside 3-acetyltransferase-I. The activity of sporaricin A tended to be greater with a reduction in inoculum size of bacteria and an increase in medium pH and decreased slightly in the presence of 10 to 50% horse serum. The in vitro activity was confirmed by in vivo tests in experimental infections with various bacteria. Its protective effect seemed to be equal to or greater than that of amikacin or dibekacin.

Amikacin↗
PubMed1980

Biphasic protection against bacterial infection in mice induced by vaccination of Propionibacterium acnes.

A single intraperitoneal injection of the phenol-treated cells of Propionibacterium acnes into mice showed nonspecific resistance against subsequent lethal doses of an intraperitoneal challenge of Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes. The protection showed a biphasic pattern. The maximum protection, designated as the early phase protection, was seen in mice injected with P. acnes vaccine 1 to 2 days before the challenge, whereas the late phase protection was seen in mice vaccinated 16 to 22 days before the challenge. The activity of the reticuloendothelial system in mice after vaccination also showed a biphasic pattern with the peak on days 4 and 12. The delayed activation of the reticuloendothelial system lasted up to 3 weeks and coincided with the period of the late phase protection. The early phase resistance was markedly impaired by the treatment with hydrocortisone and carrageenan, but not by the treatment with anti-thymocyte serum, actinomycin D, or cyclophosphamide. The number of peritoneal polymorphonuclear leukocytes in vaccinated mice increased on days 1 to 2. The number of macrophages also increased at 2 to 21 days after vaccination and reached its maximum on day 14. Total activities of acid phosphatase, Nitro Blue Tetrazolium reduction, and the phagocytic activities of peritoneal exudate cells were also enhanced on and after day 1 after the injection of P. acnes vaccine.

Animals↗
PubMed1980

[Effect of prednisolone 17-valerate 21-acetate on immunological responses in mice (author's transl)].

The in vivo effects of prednisolone 17-valerate 21-acetate (PVA), an anti-inflammatory glucocorticoid on several immunological responses in mice were investigated in comparison with hydrocortisone 17-butyrate (HB) and betamethasone 17-valerate (BV), when given subcutaneously. PVA reduced the spleen weight, the number of splenic nucleated cells, the formation of hemolytic plaque forming cells (PFC), delayed type footpad reaction and the responsiveness of splenic lymphocytes to concanavalin A. These suppressive effects were almost the same as those seen with HB and weaker than those of BV. However, the responsiveness of splenic cells to lipopolysaccharide and circulating IgM antibody response to sheep red blood cells were suppressed by a smaller dose of PVA than that of HB. PVA had no effect on the responsiveness to phytohemagglutinin-P, whereas HB and BV enhanced the phytohemagglutinin-P responsiveness. The suppressive effect of PVA on the host defense to experimental infection with Escherichia coli was weaker than those of HB and BV. From these results, PVA appears to be similar to other glucocorticoids in that it exerts complicated effects on several immunological responses in mice.

Administration, Topical↗