Further studies of swarmer cell differentiation of Proteus mirabilis PM23: a requirement for iron and zinc

Proteus mirabilis PM23, unlike other motile strains of the species, differentiates in rich fluid media to form nonseptate filaments resembling the swarmer cells formed on solid media. The swarming activity of PM23 is greater than that of the other strains on solid media and it grows faster than another strain, IM47, in differentiation-supporting broth. This faster growth is not exhibited in broth that does not support differentiation. The differentiation of PM23 in brain-heart infusion broth occurs over a wide range of pH and temperature. Inhibitors of swarming on agar plates (p-nitrophenylglycerol and boric acid) and three chelating agents (EDTA, sodium cyanide, and sodium diethyldithiocarbamate) stop differentiation both on plates and in brain-heart infusion broth; however, EGTA is not effective even at 10 mM (10 times the minimum inhibitory concentration of EDTA). The inhibitory mechanisms of p-nitrophenylglycerol and boric acid are different from that of the chelating agents. The timing of EDTA inhibition suggests generation of a "signal" to differentiate after about 2 h growth. Prevention of differentiation by addition of Fe2+ and Zn2+ up to near the time that differentiation should appear suggests that these cations have a crucial involvement in the process of initiation. However, they are not effective as additives in allowing differentiation to occur in defined media or even nutrient broth; the further addition of nucleotides or cAMP was equally ineffective.

Resistance to acute nephrotoxicity induced by cadmium-metallothionein dependence on pretreatment with cadmium chloride

Three groups of rats (B-D) were given various daily doses of CdCl2 (0.5-2 mg Cd/kg) continuously or in intervals during time periods of 1-8 weeks. Another group of animals (A) were kept untreated. At the end of the period, selected subgroups of groups A-D were given a single subcutaneous injection of 109Cd-metallothionein (109CdMT) 0.05 or 0.4 mg Cd/kg ("challenge dose"). Subsequently, urinary creatinine, protein, Cd, 109Cd and MT and kidney cortex Cd, 109Cd and MT were determined. In group A (no long term pretreatment), an increased proteinuria was observed after the rats had received the lower of the challenge doses of 109CdMT, and an even greater increase after the higher challenge dose of 109CdMT. No such increase appeared in group B, C and D (repeatedly pretreated with CdCl2) at either of the challenge doses. Higher metallothionein concentrations in kidney cortex observed in the pretreated groups constitute a plausible explanation of the protective effects of pretreatment against the development of increased proteinuria after challenge dosing. It is likely that increasing Cd concentrations, gradually accumulating in the renal cortex (22-226 micrograms/g wet wt.) as a result of the pretreatment, served to induce the synthesis of metallothionein in the renal cortical cells, thus making them resistant to the challenge from 109CdMT.

Influence of cadmium-metallothionein pretreatment on tolerance of rat kidney cortical cells to cadmium toxicity in vitro and in vivo

Kidney cells were isolated from rats pretreated by daily subcutaneous doses of cadmium metallothionein (CdMT: 0.05-0.2 mg Cd/kg X 5) and from non-pretreated rats. Upon exposure to CdCl2 in vitro (0-200 micrograms Cd/ml), a concentration dependent decrease in viability was observed in the non-pretreated cells, while no such decrease occurred in the pretreated cells indicating that these cells were more resistant to the toxic action of cadmium. There was a higher in vitro uptake of Cd+2 and an increased metallothionein (MT) concentration in the pretreated cells (compared to non-pretreated cells). Subcellular distribution studies revealed that Cd was mainly recovered in the "cytosol" fraction. The higher total cadmium uptake in pretreated cells corresponded to an increase of Cd in "cytosol" and "nuclear" fractions. This observation may be explained by MT-binding of Cd in the cells and is in accordance with a possible protective effect of induced MT in the pretreated cells. In order to assess whether pretreatment-induced tolerance to cadmium toxicity--indicated by the cellular studies--could also be observed in vivo, some whole animal experiments were also performed. A dose-related proteinuria was observed in non-pretreated rats after a single subcutaneous administration of 109Cd-MT at doses of 0.05 and 0.4 mg Cd/kg. Urinary total Cd, 109Cd and MT was also increased in a dose-related fashion. Cadmium concentrations in kidney were dose related and reached 19 micrograms/g wet weight. In contrast, in animals repeatedly pretreated with CdMT according to 1), no proteinuria was observed after administration of the same single doses of 109CdMT. Total Cd. 109Cd and particularly MT-concentrations in urine were lower in such pretreated animals than in in non-pretreated ones in spite of the accumulation of higher tissue concentrations of total Cd (up to 80 micrograms/g). The pretreatment was thus shown to prevent some of the acute nephrotoxicity of CdMT, possibly by means of induction of MT synthesis.

Urease activity related to the growth and differentiation of swarmer cells of Proteus mirabilis

Urease activity was measured using whole cells of both long (swarming) and short (nonswarming) populations of Proteus mirabilis from casein hydrolysate agar (CHA) and broth (CHB) cultures, and from brain heart infusion broth (BHIB) cultures. Urease is a constitutive enzyme for both long and short cells, but its activity was tremendously increased when urea was incorporated into the media. Urease production was also affected by culture age and media used. Before exponential phase, urease activity was very low, and it increased to its highest point after about 4 h in BHIB and 8 h in both CHA and CHB cultures at 37 degrees C. Long cells had higher urease activity than did short cells when grown on CHA, and was also expressed by two different strains cultured in BHIB. Strain PM23, in BHIB, was able to form long cells (swarming cells) to a maximum proportion after about 4 h, but strain IM47 could not differentiate in any of the liquid media. The former had more urease when swarming differentiation was initiated. PM23 grew relatively faster than IM47 when the former began to differentiate, but this fast growth could not be observed when nutrient broth or minimal medium was used. These observations suggest that long or swarming cells are "faster growing" rather than "nongrowing bacteria".

Uptake of cadmium in isolated kidney cells--influence of binding form and in vivo pretreatment

Uptake of cadmium as 109CdCl2, 109Cd-cysteine, 109Cd-albumin and 109Cd-metallothionein was studied in isolated kidney cells from rat. Cd as 109CdCl2 and 109Cd-albumin was taken up at similar rates. The uptake of cadmium as 109Cd-cysteine was greater and that of 109Cd-metallothionein lower compared with that of the other substances. These observations were made on non-pretreated cells. In cells taken from rats pretreated with CdCl2 in vivo, the uptake of cadmium as 109CdCl2, 109Cd-cysteine and 109Cd-albumin was lower than in cells from non-pretreated rats. However, the uptake of 109Cd-metallothionein was considerably enhanced in pretreated cells. In pretreated kidney cells the decreased uptake of Cd (as Cd-albumin) might be related to protection of the kidney against acute Cd toxicity and increased uptake of metallothionein-Cd might contribute to the explanation of renal damage in long-term Cd exposure.

Cadmium toxicity in kidney cells. Resistance induced by short term pretreatment in vitro and in vivo

Epithelial cells from the kidney were freshly isolated from rats pretreated by daily subcutaneous doses of CdCl2 in vivo (0.5-2 mg Cd/kg X 5). Such cells were incubated in vitro in media with different concentrations of cadmium chloride (0-200 micrograms Cd/ml). There was no inhibition of cell growth in such cells. However, in cells isolated from non-treated rats, in vitro exposure to the same concentrations of CdCl2 caused a dose dependent decrease in viability. When cells, isolated from non-treated rats were pretreated in vitro with CdCl2 (10 micrograms/ml) and subsequently exposed to cadmium chloride (0-200 micrograms/ml), a protective effect was observed, which was similar to the one observed in cells isolated from animals pretreated with CdCl2. The concentration of metallothionein in the cells treated with cadmium was increased. A lower uptake of cadmium chloride, in vitro has been observed in kidney cells pretreated in vivo or in vitro compared to nonpretreated cells. Subcellular distribution studies indicate that Cd-distribution was similar in pretreated and non-pretreated cells, but concentrations were generally lower in the pretreated cells. The decreased uptake of Cd by pretreated kidney cells is a sign of Cd-interference with cellular function. These changes are suggested as a contributing mechanism to the prevention of acute toxic effects of cadmium on the kidney.

Epidural beta-endorphin in treatment of pain

Epidural administration of 3 mg of synthetic beta-endorphin produced analgesia in 10 patients with intractable pain due to disseminated cancer. Mean onset of relief of pain was 24 +/- 3 minutes and the mean duration of analgesia was 19 +/- 3 hours. The onset of analgesia produced by the epidural injection of beta-endorphin was slower and the duration less than those observed after intrathecal injection.

Effect of exogenous beta-endorphin on anterior pituitary hormone secretion in man

The effect of large amounts of synthesized human beta-endorphin (beta-EP) administered intrathecally on pituitary-adrenocortical function was investigated by determining the plasma levels of ACTH, cortisol, growth hormone and prolactin in 8 patients with pain caused by severe disseminated cancer. They were divided into 2 groups, an Ep group of 8 patients and a control group of 5 of the same 8 patients. There were no significant effects of beta-Ep on plasma ACTH, cortisol and growth hormone levels. However, the injection of beta-Ep into human subjects resulted in a rise in plasma concentrations of prolactin.

Profound analgesic effects of beta-endorphin in man

Profound and long-lasting analgesia (mean duration of pain relief 33.4 h, range 22.5--73.5 h) was produced by intrathecal administration of 3 mg synthetic beta-endorphin in all of 14 patients with intractable pain due to disseminated cancer. No respiratory depression, hypotension, hypothermia, or catatonia was observed.

Effects of anaesthesia and surgery on plasma aldosterone concentration and renin activity in man

The effects of various anaesthetic agents and surgery on the plasma concentrations of aldosterone and on renin activity were investigated in 76 patients. The plasma concentration of aldosterone was increased markedly by 2.5 times the control value during 45 min of ether anaesthesia. It was increased also during halothane, methoxyflurane and enflurane anaesthesia. Spinal anaesthesia did not alter significantly the plasma concentration of aldosterone. Plasma renin activity and ACTH concentration were increased slightly during general anaesthesia.