Weight bearing after arthrodesis of the first metatarsophalangeal joint. A randomized study of 61 cases.

We performed a prospective randomized study of 61 cases of arthrodesis of the first metatarsophalangeal joint in 56 patients. In the first group, full weight bearing was allowed after 2-4 days and in the second group at 4 weeks. Radiographic union of the arthrodesis in the two groups did not differ.

Cell-bound and extracellular autolytic activity of a tolerant and a nontolerant Staphylococcus aureus strain exposed to methicillin.

Cell-bound and extracellular autolytic activity was studied in a tolerant and a non-tolerant Staphylococcus aureus strain after exposure to low (10 mg/l) and high (80 mg/l) concentrations of methicillin. Tolerance was defined as survival after 24 h of over 2% of the inoculum after exposure to high concentrations of methicillin (greater than or equal to 64 mg/l). The nontolerant strain showed an increased cell-bound autolytic activity after exposure to both low and high concentrations of methicillin. The tolerant strain on the other hand selectively showed a reduced cell-bound autolytic activity after exposure to 80 mg/l of methicillin. In both types of strains extracellular activity was less after exposure to a high concentration of methicillin than after exposure to a low concentration. This phenomenon was caused by the release of an inhibitor of the autolysins under the influence of the high concentration of methicillin.

[Mycotic placentitis in cattle]. / Mycotische placentitis bij het rund.

Two cases of bovine mycotic placentitis are reported. The two cows did not show any clinical symptoms before or during premature delivery of two clinically normal calves. In both placentas a severe placentitis accompanied by extensive necrosis and a large number of hyphae was present in two placentas. Aspergillus fumigatus was isolated in one case. The literature on bovine mycotic placentitis is reviewed in the discussion.

Responses of tolerant and nontolerant Staphylococcus aureus strains to methicillin treatment in an experimental infection in mice.

Staphylococcus aureus strains can be divided into tolerant and nontolerant strains on the basis of their survival in vitro in the presence of high concentrations of methicillin (greater than or equal to 64 micrograms/ml). A strain is defined as tolerant if more than 2% of the inoculum survives under these conditions. The response of five susceptible and five tolerant S. aureus strains to treatment with methicillin was studied in an experimental thigh infection in mice. Animals were treated with one and two injections of methicillin (2.5 mg per mouse). At the end of treatment, the number of CFUs in the thigh muscles infected with the susceptible strains was found to be significantly lower than that in the thigh muscles infected with the tolerant

Tolerance percentage as a criterion for the detection of tolerant Staphylococcus aureus strains.

In this study, the degree of tolerance was determined in several populations of Staphylococcus aureus isolates. The degree of tolerance of a staphylococcal strain can be established in a reproducible way by exposing the strain to increasing concentrations of a beta-lactam antibiotic and determining the number of surviving bacteria at each concentration. The number of surviving bacteria was expressed as a fraction of the initial inoculum. By this technique, it appears that for each strain the value of the surviving fraction stabilized above a certain concentration of the antibiotic. This value was called the tolerance percentage of the strain. In 64 S. aureus strains isolated from blood cultures in 1982, the tolerance percentages, after exposure to methicillin, varied from less than or equal to 0.1 to 6; 28% of the strains showed a tolerance percentage of less than or equal to 0.1, and 12.5% showed a tolerance percentage of greater than or equal to 2. Similar tolerance percentages were found with cloxacillin, nafcillin, cephalothin, and penicillin. Strains with a tolerance percentage of greater than or equal to 2 showed slow killing and lysis in the presence of a high methicillin concentration. A tolerance percentage of 2 appeared to be the breakpoint between susceptible and tolerant strains. Older collections of S. aureus strains, dating from the years 1951 to 1953 and 1957 to 1958, also included strains with a survival percentage of greater than or equal to 2, thus indicating that tolerance of S. aureus to beta-lactam antibiotics is not a new phenomenon.

Efficacy of continuous versus intermittent administration of penicillin G in Streptococcus pneumoniae pneumonia in normal and immunodeficient rats.

An experimental Streptococcus pneumoniae pneumonia was used to study the influence of continuous versus intermittent administration of penicillin G on therapeutic efficacy in normal rats and in rats whose phagocytic capacities were impaired by decomplementation with cobra venom factor. Response to antibiotic treatment was evaluated with respect to numbers of bacteria in left lung, blood and pleural fluid. Penicillin treatment was started 36 h after bacterial inoculation, and continued for four days. With intermittent intramuscular administration of penicillin normal rats were cured after daily doses of 4 mg/kg at 12 h intervals, whereas decomplemented rats recovered only after daily doses of 100 or 102 mg/kg at 12 h or 8 h intervals, respectively. When penicillin was administered by way of continuous infusion, daily doses of 3.5 mg/kg were required for a cure of infections in both normal rats and in decomplemented rats. This treatment resulted in a constant level of 0.05 micrograms of penicillin per ml, which was slightly above the minimum bactericidal concentration for the infecting strain. These findings show that maintenance of bactericidal levels of penicillin were particularly important in curing severe infection in rats with impaired defense.

Changes in oestradiol, progesterone and testosterone concentrations in follicular fluid and in the micromorphology of preovulatory bovine follicles relative to the peak of luteinizing hormone.

Preovulatory bovine follicles (n = 58) were collected at different times after the onset of standing oestrus when cows would allow mounting until shortly before ovulation, which occurred 24 +/- 1.4 h after the peak level of LH in the peripheral blood. Non-atretic antral follicles (n = 71) of 3-20 mm were also collected from cows during the luteal phase of the oestrous cycle. The follicular fluid was aspirated for the radioimmunoassay of oestradiol-17 beta, progesterone and testosterone. The follicular wall was examined micromorphologically. Follicular fluid steroid levels were compared in 2-h periods relative to the LH peak. The development of the preovulatory follicles from onset of oestrus to ovulation can be divided into four phases. Phase 0 (after onset of oestrus but before LH surge) was characterized by a high level of oestradiol (6.05 mumol/l); the levels of progesterone and testosterone were lower (0.387 and 0.165 mumol/l respectively) but higher than in non-atretic luteal follicles of similar size. The theca interna (TI) was wider and the membrana granulosa (MG) cells were larger than those of non-atretic antral follicles. During phase 1 (0-6 h after the LH peak) oestradiol remained constant but at a lower level, progesterone increased (0.727 mumol/l) and testosterone was higher from 0 to 2h after the LH peak (0.241 mumol/l). The TI was 40% wider, whereas the size of the MG cells remained the same. In phase 2 (6-20 h after the LH peak) the level of oestradiol dropped rapidly during the period from 6 to 10 h, that of progesterone decreased to the same level as in phase 0 and that of testosterone was low (0.031 mumol/l). The width of the TI decreased to that of preovulatory follicles in phase 0 and the MG cells were slightly larger. In phase 3 (20 h after the LH peak until ovulation) the level of oestradiol decreased further (0.461 mumol/l) and that of testosterone remained low. Progesterone increased to the highest levels observed (1.51 mumol/l), however, and this coincided with a 39% increase in the size of the MG cells, whereas the width of the TI remained the same as in the preceding phases 0 and 2. In phase 3 the basement membrane began to disintegrate and phagocytic cells could be observed. This points to a simultaneous functional and morphological luteinization. It is suggested that these changes in follicular steroid levels and micromorphology are regulated by the preovulatory LH peak.

Intrarenal distribution of ampicillin in the healthy and the infected rat kidney: a comparison of methods.

The ampicillin concentration in the cortex of the normal and the infected rat kidney was determined by means of three different methods: tissue homogenate analysis, renal lymph analysis, and autoradiography. Both tissue homogenate analysis and autoradiography revealed that the cortical ampicillin concentration was about five times as high as the serum concentration. Renal lymph analysis disclosed that the ampicillin concentration in this fluid amounted to about 93% of the serum concentration. The discrepancy between these results can be explained on the basis of the binding of ampicillin to cellular components in the cortex. The results of the study of ampicillin distribution in infected rat kidneys with the aid of tissue homogenate analysis and autoradiography indicate that the ampicillin concentration was lower in the affected than in the intact tissue. Renal lymph analysis showed that the ampicillin concentration in the lymph was not affected by the presence of the infection. Quantitative autoradiography demonstrated that the ampicillin concentration in the cortical foci of infection was of the same order of magnitude as the serum concentration. For this kind of study autoradiography together with lymph analysis are recommended.

Ampicillin susceptibility and ampicillin-induced killing rate of Escherichia coli.

The killing rate induced by ampicillin was determined in 20 strains of Escherichia coli. The apparent generation rate constant for each E. coli showed a characteristic concentration-dependent course. This course can be mathematically described and is determined by four parameters. Three of these parameters determine the speed of the process, and the fourth parameter determines a minimal concentration. The susceptibility of the strains, measured as the minimal inhibitory concentration by an agar dilution method, correlated with the minimal concentration and with a minimal inhibitory concentration calculated from the curve, but not with the rate-determining parameters.

Factors influencing detection of tolerance in Staphylococcus aureus.

The phenomenon of tolerance to cloxacillin and methicillin was studied in Staphylococcus aureus. It was demonstrated that the minimal bactericidal concentrations showed marked differences, depending on the method of detection used. These differences resulted from carry-over of the antibiotic to the subculture plates. When carry-over of the antibiotic was prevented by the addition of beta-lactamase to the nutrient medium, the antibiotics were no longer bactericidal. At a certain antibiotic concentration and at higher concentrations, however, each strain showed a certain survival percentage after 24 h. The tolerance percentage was determined for 15 strains. The values found for the individual strains ranged from less than 0.1 to 11% for cloxacillin and methicillin. since these percentages were reproducible within narrow limits, they could be regarded as a characteristic of the strains. The tolerance percentage was independent of the growth phase of the initial cultures.

Premature changes in surface activity in lung fluid of fetal lambs.

The present study was conducted to monitor changes in surface activity of lung and amniotic fluid of premature lambs. Lung fluid was continuously obtained from 10 tracheotomized fetal lambs (gestational age 98-112 days) until (premature) parturition. Amniotic fluid was sampled twice a week from 3 other lambs by catheterization, and during cesarean section at the end of the gestational period from another 3 lambs. Surface activity in lung fluid increased on the first postoperative day, the more so when this occurred at a later fetal age in the period of 98-112 days. These findings show that even before day 110 'stress' can result in a release of surface active material. A return to low surface activity (about 26 mN/m) was observed within 3 to 6 days. Thereafter, between days 110 and 120, surface activity increased steeply within the individual animals but with large variability between the fetuses. The steep and premature increased was followed by a further but slow increase during the mature period and Ymin values of approximately 2 mN/m were reached. Amniotic fluid surface activity changed slowly with gestational age, but did not reach Ymin values of less than 15 mN/m. Lung fluid total phospholipid phosphorus values were low (about 6 micro M) up to 125 days, when they increased rapidly (greater than 16 micro M). Lung fluid production increased from 4.9 ml/h at the beginning of the experiment to 12.1 ml/h after day 130 but decreased dramatically 1-3 days before (premature) parturition. Experiments on fetal lung maturation should be started before day 105 of gestation and we suggest that measurement of surface activity of fetal lung fluid may be useful in monitoring changes in the premature alveolar type II cells of lambs.

Myometrial electrical activity throughout the entire course of pregnancy in the ewe.

Bipolar electrodes were implanted into the myometrium of three cycling ewes. Natural mating took place 35, 47 and 91 days after surgery, and all three animals became pregnant. Two of them were slaughtered 18 and 40 days after mating, the third delivered twin lambs 144 days after mating. The uterine electrical activity was recorded during pregnancy and parturition. From the 3rd until the 27th day after mating the uterus appeared to be quiescent. From the 5th wk of pregnancy until induction of parturition on day 141, electrical activity was observed to occur in episodes of 5--10 min, with a frequency of 1--3 per 2 h. The episodes are separated by periods of inactivity. The amplitudes of the electrical discharges increased gradually during pregnancy, although the plasma progesterone levels increased also. It is concluded that (1) the implanted electrodes did not interfere with normal reproductive processes such as conception, maternal recognition of pregnancy, implantation and fetal development: (2) a distinct pattern of electrical activity can be detected as early as the 5th wk of pregnancy.

In-vivo myometrial electrical activity in the cyclic mare.

Uterine electromyography was performed by means of chronically implanted surface electrodes in 3 Pony mares during spontaneous oestrous cycles and following luteolysis induced by a prostaglandin analogue (fluprostenol). Three distinct patterns were recognized during the oestrous cycle. (1) During oestrus well defined phases of activity with closely grouped high-amplitude spikes were separated by long periods (10-45 min) of complete inactivity. (2) During dioestrus more diffuse phases of activity with low-amplitude spikes were separated by variable periods of relative inactivity. (3) During luteolysis, short and frequently occurring phases of activity were propagated between the two electrodes on one uterine horn; a similar pattern also occurred between 1 and 3 h after injection of fluprostenol. Peripheral plasma progesterone, but not total inconjugated oestrogen, concentrations were closely related to characteristics of the myographic activity during the cycle. Insemination during oestrus and injection of fluprostenol during dioestrus caused a marked and prolonged increase in myometrial electrical activity. Almost any non-specific environmental stimulus, including entry by palpation of the genital tract per rectum and vaginoscopic examination, but these were of brief duration and the normal resting pattern of activity was quickly re-established after completion of the manipulations.

Uterine position and presentation of minipig-fetuses and their order and presentation at birth.

Uterine position and presentation of fetuses in 17 minipigs during pregnancy were compared with their order and presentation at birth. Fetuses from 1 or both uterine horns were marked between day 80 and day 105 of gestation by 1 or more transuterine injections of either a 2.5% solution of dianil blue (3 animals) or a radiopaque substance (14 animals). Roentgenograms of the newborn pigs, which were ear-notched immediately after birth, enabled making individual identification. Pigs seemed to be delivered randomly from the 2 uterine horns. They either followed a neighbor from the same horn (n = 42) or followed a pig from the contralateral horn (n = 52). Only in 3 dams did 1 uterine horn become empty before delivery from the other horn started. In 4 dams, 1 pig passed its neighbor from the same horn, thereby being born earlier than expected. Moreover, passing of pigs could have occurred and gone undetected in those dams from which the pigs of only 1 horn were marked. This passing might have taken place within the uterine body. From 18 of 95 pigs (19%) , the presentation at birth differed from the one observed at laparotomy.

Indication of increase of the lecithin/sphingomyelin (L/S) ratio in lung fluid of lambs maternally treated with metabolite VIII of Bisolvon.

Metabolite VIII of Bisolvon (Met. VIII) was administered to six pregnant ewes (i.m. daily 5 or 10 mg/kg for 7-9 days). The treatment was started at the 116th/117th or 117th/118th day of gestation and in one case the drug was given to the fetus (i.v. 2 mg/ml/h). Fetal lung fluid obtained from chronically implanted catheters was used for the estimation of the lecithin/sphingomyelin ratio. The maternal treatment with Met. VIII resulted in a significantly increased growth of the L/S ratio compared to the control group (n=4). In three lambs a sharp increase of the L/S ratio was noticed during the last days of Met. VIII treatment. The time gap between first treatment and noticeable effect was 6-8 days. It is postulated that the noticed increase of L/S ratio is the consequence of Met. VIII treatment and very unlikely the result of a release of glucocorticoticoids.