Metal-tolerant morganella morganii isolates can potentially mediate nickel stress tolerance in Arabidopsis by upregulating antioxidative enzyme activities

Plant growth-promoting rhizobacteria (PGPRs) have been utilized to immobilize heavy metals, limiting their translocation in metal contaminated settings. However, studies on the mechanisms and interactions that elucidate how PGPRs mediate Nickel (Ni) tolerance in plants are rare. Thus, in this study we investigated how two pre-characterized heavy metal tolerant isolates of Morganella morganii (ABT9 and ABT3) improve Ni stress tolerance in Arabidopsis while enhancing its growth and yield. Arabidopsis seedlings were grown for five weeks in control/Ni contaminated (control, 1.5 mM and 2.5 mM) potted soil, in the presence or absence of PGPRs. Plant growth characteristics, quantum yield, and antioxidative enzymatic activities were analyzed to assess the influence of PGPRs on plant physiology. Oxidative stress tolerance was quantified by measuring MDA accumulation in Arabidopsis plants. As expected, Ni stress substantially reduced plant growth (shoot and root fresh weight by 53.25% and 58.77%, dry weight by 49.80% and 57.41% and length by 47.16% and 64.63% over control), chlorophyll content and quantum yield (by 40.21% and 54.37% over control). It also increased MDA content by 84.28% at higher (2.5 mM) Ni concentrations. In contrast, inoculation with M. morganii led to significant improvements in leaf chlorophyll, quantum yield, and Arabidopsis biomass production. The mitigation of adverse effects of Ni stress on biomass observed in M. morganii-inoculated plants was attributed to the enhancement of antioxidative enzyme activities compared to Ni-treated plants. This upregulation of the antioxidative defense mechanism mitigated Ni-induced oxidative stress, leading to improved performance of the photosynthetic machinery, which, in turn, enhanced chlorophyll content and quantum yield. Understanding the underlying mechanisms of these tolerance-inducing processes will help to complete the picture of PGPRs-mediated defense signaling. Thus, it suggests that M. morganii PGPRs candidate can potentially be utilized for plant growth promotion by reducing oxidative stress via upregulating antioxidant defense systems in Ni-contaminated soils and reducing Ni metal uptake.

Amniotic fluid thyrotropin (TSH) following maternal administration of thyrotropin releasing hormone

Cord blood and amniotic fluid thyrotropin (TSH), T4, T3, and rT3 concentrations were measured in 49 women who received 400 micrograms thyrotropin releasing hormone (TRH) iv during labor and in 16 control women who received saline. Cord blood serum TSH concentrations were elevated for as long as 4 hours after TRH administration and peak values (38.0 +/- 4.2 microU/ml) were observed from 61-120 minutes after TSH as compared to control values of 5.0 +/- 0.3 microU/ml. The elevations in fetal TSH concentration stimulated the fetal thyroid, resulting in a progressive increase in cord blood T4 and T3 but not rT3 concentrations. These TRH induced elevations in fetal cord blood TSH concentrations were not accompanied by increases in unconcentrated and 4 fold concentrated amniotic fluid TSH concentrations which were almost always below 0.6 microU/ml, the limit of assay sensitivity. Unconcentrated amniotic fluid T4 concentrations were barely detectable and no variation was observed between the TRH treated and saline treated mothers; amniotic fluid T3 was not detectable in any of the groups; and amniotic fluid rT3 concentrations ranged between 46.4 and 55.6 ng/dl and did not differ between groups. These findings suggest that term amniotic fluid TSH values do not reflect transient but marked elevations in fetal serum TSH concentrations and that amniotic fluid TSH determination is probably not useful in the detection of primary fetal hypothyroidism. It is possible, but unlikely, that long-term and even greater elevations in fetal serum TSH concentrations would result in increased amniotic fluid TSH concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of iodine administration on thyroid function in diabetic patients

Iodide-induced hypothyroidism has been observed in subjects treated with compounds with mild antithyroid activity. The hypoglycemic agent tolbutamide belongs to the aminoheterocyclic group, a class of compounds with antithyroid effect. Thus it was thought interesting to study the effect of large doses of iodide on thyroid function in diabetics chronically treated with tolbutamide. Basal thyroid function as assessed by clinical examination and iodothyronine and TSH concentrations was normal in all patients. Furthermore, in diabetics treated with tolbutamide, hormone concentrations were not different from those of patients treated with insulin or diet. Serum T4, T3 and TSH did not show any significant variation throughout the investigation period. Our results suggest that thyroid function is not affected by chronic treatment with tolbutamide even when large doses of iodide are administered.

Inhibition of foetal growth hormone (GH) and thyrotrophin (TSH) secretion after maternal administration of somatostatin

Somatostatin (SRIF) was infused (500 micrograms over 30 min) into 68 pregnant women during labour. As a control, saline was infused into 26 pregnant women. Maternal blood was obtained prior to the infusion and at delivery and cord blood was obtained at delivery. The subjects were divided into 4 groups based upon the interval of time from the termination of SRIF infusion and delivery. There was a marked decrease in cord blood thyrotrophin (TSH) from 0 to 180 min and in cord blood growth hormone (GH) from 0 to 120 min following SRIF infusion. SRIF infusion did not affect cord blood iodothyronine and thyroglobulin concentrations. SRIF administration induced a small but significant (P less than 0.05) decrease in serum GH concentration but had no other effect on maternal hormone values. These studies strongly suggest that SRIF crosses the human placenta and transiently suppresses foetal anterior pituitary TSH and GH secretion.

Dermorphin, a new opioid peptide, stimulates thyrotropin secretion in normal subjects

The effect of a recently described, potent opioid peptide, dermorphin (DER), on TSH secretion in euthyroid subjects has been studied. DER infused at a rate of 5.5 micrograms/Kg/min for 30 min induced a significant increase in serum TSH concentration at 60, 90, and 120 min after the infusion was begun. Treatment with naloxone administered 30 min before the DER infusion with a bolus dose of 4 mg, followed by a constant infusion of 1 microgram/Kg/min for 150 min, prevented the rise in serum TSH. Naloxone administered alone did not induce any change in TSH concentration. The present findings suggest that DER has a stimulatory effect on TSH secretion, probably mediated by opioid receptors. These results, however, do not solve the question as to whether opioids have a physiological role in the control of pituitary TSH secretion.

Failure of metoclopramide to affect thyrotropin concentration in the term human fetus

Metoclopramide (MET), a potent dopamine receptor-blocking drug, or saline was administered to 125 term pregnant women at various time intervals (5-412 min) before delivery. Maternal serum was obtained before and after MET injection. Cord blood was obtained at delivery in MET-treated and saline-treated (control group) women. No significant changes in serum TSH, T4, T3, or rT3 concentrations were observed in maternal or cord blood after MET administration. These results suggest that, in contrast to euthyroid nonpregnant women and men, MET administration does not induce a rise in serum TSH concentration in term pregnant women or in the term fetus. Thus, the dopaminergic inhibitory effect on anterior pituitary TSH secretion may not be an important factor in TSH regulation during pregnancy or in the fetus, or the dose of MET employed may be unable to overcome the dopamine inhibitory effect.

Effect of metoclopramide on maternal and fetal hyperprolactinemia

To investigate the effect of metoclopramide (MET), a dopaminergic antagonist drug, on serum PRL concentration in maternal and cord blood (CB) serum, the drug was injected in 94 at term pregnant women whereas 28 mothers received saline. Maternal serum (MS) samples were obtained before MET injection and at the parturition time. According to the interval of time between MET administration and birth, MS specimens were grouped in 7 groups. CB was obtained from neonates whose mothers were injected with saline, group 0 and from newborns whose mothers were treated with MET, groups 1 to 7. In the 7 groups of women the mean PRL concentration before MET ranged between 307 and 439 ng/ml. After MET injection a significant increase has been observed in all groups with a minimum and maximal mean value of 639 and 931 ng/ml. The highest net increment of PRL has been measured in group 1 sampled at 5 to 30 minutes after MET. CB PRL concentration in group 0, saline treated, was not different from the values measured in group 1 to 7, treated groups, with a range between 504 and 703 ng/ml. These findings suggest that maternal lactotropes are still responsive to MET. On the opposite, fetal pituitary does not release PRL after MET injection probably because PRL secretory activity is maximal or because the dopaminergic receptors' system is still immature.

Iodothyronine and thyrotropin concentrations after iodoamide administration for angiographic studies

In order to study the effect of iodoamide (a contrast medium widely used for urographic and arteriographic studies) on thyroid function, seventeen subjects were studied before and after arteriographic examinations employing this contrast compound. Serum concentrations of T4, T3, rT3 and TSH were not modified during the observation period by the administration of iodoamide. This finding is in contrast with the observation that iopanoic acid and ipodate, used for cholecystographic examinations, can reduce the serum concentrations of T4 and T3 with a concomitant increase in rT3. Therefore, iodoamide is not useful in the treatment of hyperthyroidism.

Response of growth hormone to thyrotropin-releasing hormone during fetal life

The effect of TRH administration to the term pregnant women on the GH response in cord blood (CB) was evaluated in 138 subjects. Previous studies have demonstrated that TRH readily crosses the placenta. TRH (400 microgram) was administered iv to 59 pregnant women just before delivery. CB samples were obtained at delivery and assigned to 6 groups, depending upon the duration of time between TRH injection and CB sampling. The control group comprised 79 pregnant women who received saline. A progressive rise and then a fall in the CB GH concentration were observed after TRH administration. Values were significantly elevated 61-90 min after TRH administration compared to values in saline-treated subjects (19.3 +/- 3.1 vs. 13.1 +/- 0.9 ng/ml; P less than 0.05). The present study is the first report of the effect of TRH on the GH concentration in CB and suggests that TRH stimulates GH release in the fetus.

The value of serum thyroglobulin measurement as a marker of cancer recurrence in the follow-up of patients previously treated for differentiated thyroid tumor

In order to verify the value of serum thyrogolbulin (hTg) determination to detect cancer recurrence, 104 patients previously treated with surgical and 131I total thyroid ablation of differentiated thyroid cancer were studied. Comparison of serum hTg results and 131I total body scans (131I TBS) was attempted. In 87 patients with negative 131 I TBS, serum hTg was undetectable in 80% of the patients whereas in 20% detectable amounts of hTg were measured. In 57 patients with positive 131I TBS, serum hTg was measurable in 72% of the patients whereas in 20% was undetectable. These contrasting results of serum hTg measurement and 131I TBS suggest to us the usefulness to use both tests in the detection of thyroid cancer recurrence.

Human cord blood concentrations of thyrotropin, thyroglobulin, and iodothyronines after maternal administration of thyrotropin-releasing hormone

TRH or saline was administered to 214 term pregnant women at various time intervals (8-820 min) before delivery. Cord blood (CB) was obtained, and plasma TSH, T4, T3, rT3, and thyroglobulin concentrations were measured by specific RIA. CB TSH was significantly elevated within 20 min after TRH administration and remained elevated for 180 min. CB T3 rose significantly by 60 min and remained elevated for 820 min. CB T4 was significantly increased from 120 to 820 min after TRH administration. There was no significant change in the CB thyroglobulin concentration. These findings demonstrate for the first time that TRH crosses the human placenta, that the fetal pituitary is responsive to TRH, and that endogenous TSH stimulates the fetal thyroid.

Effects of somatostatin in a case of severe hypoglycemia due to nesidioblastosis

The Authors have studied the effects of somatostatin (SRIF) treatment in an infant affected by hypoglycemia due to nesidioblastosis. During iv infusion with SRIF we observed a marked increase of blood glucose levels; concomitantly insulin secretion was almost completely suppressed. In contrast, during treatment with protamine zinc-somatostatin (PZ-SRIF), a long acting SRIF preparation, the blood glucose levels did not rise and insulin concentrations were inappropriately elevated. Therefore in this case the long term treatment of hypoglycemia due to nesidioblastosis with PZ-somatostatin was unfeasible.

Serum concentrations of myoglobin, creatine kinase, lactate dehydrogenase and cardiac isoenzymes in euthyroid, hypothyroid and hyperthyroid subjects

Serum concentrations of myoglobin, creatine kinase and lactate dehydrogenase were measured in 33 euthyroid, 21 hyperthyroid and 15 hypothyroid subjects. The results showed that myoglobin, creatine kinase and lactate dehydrogenase were increased and decreased in the hypo- and hyperthyroid states, respectively. In addition, the concentrations of myoglobin, creatine kinase and lactate dehydrogenase values were inversely related to both the thyroxine and triiodothyronine concentrations. To study the origin of the increased muscle protein values observed in hypothyroidism, the cardiac isoenzyme fractions were measured; the results obtained support the view that the muscle enzymes are mainly derived from skeletal muscles.