Sensitization by dexamethasone of lymphocyte cyclic AMP formation: evidence for increased function of the adenylyl cyclase catalyst

1. Glucocorticoids and elevations of intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP) may affect lymphocyte activation, proliferation and effector functions in similar ways. Therefore, we have investigated the effects of the glucocorticoid, dexamethasone, on human lymphocyte cyclic AMP formation. 2. Treatment of resting human lymphocytes with the glucocorticoid, dexamethasone, sensitized prostaglandin E2-stimulated cyclic AMP accumulation in a time- and concentration-dependent manner. 3. In membranes of lymphocytes treated for 24 h with 100 nM dexamethasone, maximal adenylyl cyclase activity stimulated by prostaglandin E2, isoprenaline, guanosine 5'-triphosphate (GTP), forskolin and MnCl2 was significantly enhanced; the EC50 for these agents was not significantly altered. 4. beta 2-Adrenoceptor density, immunodetectable alpha-subunits of the G-proteins Gs and Gi, and pertussis toxin-substrates were not significantly altered by dexamethasone treatment. 5. In dexamethasone-treated lymphocytes, prostaglandin E2-mediated inhibition of concanavalin A-induced Ca2+ elevations was doubled compared to control cells. 6. Based on these data and the observation that enhancement of forskolin- and MnCl2-stimulated adenylyl cyclase activity could quantitatively account for the enhancement of prostaglandin E2-, isoprenaline- or GTP-stimulated adenylyl cyclase activity, we conclude that dexamethasone treatment sensitizes cyclic AMP formation in resting human lymphocytes by altering the adenylyl cyclase catalyst rather than G-proteins or hormone receptors. This results in an enhanced capability of cyclic AMP generating agonists to inhibit early steps of lymphocyte activation.

Autogenic-feedback training: a potential treatment for orthostatic intolerance in aerospace crews

Postflight orthostatic intolerance has been identified as a serious biomedical problem associated with long-duration exposure to microgravity in space. High priority has been given to the development of countermeasures for this disorder that are both effective and practical. A considerable body of clinical research has demonstrated that people can be taught to increase their own blood pressure voluntarily, and that this is an effective treatment for chronic orthostatic intolerance in paralyzed patients. The current pilot study was designed to examine the feasibility of adding training in control of blood pressure to an existing preflight training program designed to facilitate astronaut adaptation to microgravity. Using an operant conditioning procedure, autogenic-feedback training (AFT), three men and two women participated in four to nine training (15-30-minute) sessions. At the end of training, the average increase in systolic and diastolic pressure, as well as mean arterial pressures, that the subjects made ranged between 20 and 50 mm Hg under both supine and 45 degrees head-up tilt conditions. These findings indicate that AFT may be a useful alternative treatment or supplement to existing approaches for preventing postflight orthostatic intolerance. Furthermore, the use of operant conditioning methods for training cardiovascular responses may contribute to the general understanding of the mechanisms of orthostatic intolerance.

Towards a broader view of recovery

It is estimated that tobacco use accounts for 25% of the total economic cost of illness in America. Chemically dependent patients have a smoking rate that ranges from 80% to 95% in different studies, almost triple the national average. Despite these staggering statistics, only a handful of chemical dependency treatment programs treat nicotine as an addictive drug and actively encourage their patients to quit. Denial by treatment staff and fears in the Recovery community that Recovery would be jeopardized by quitting are two factors contributing to the reluctance to develop smoke-free programs and treat nicotine dependence. The fear that patients would refuse admission to a facility that prohibits smoking and resistance from staff who smoke appear to be the major barriers to adopting a smoke-free policy. The time has come to face the burdensome costs of tobacco use and to address nicotine dependence in chemical dependents. It is time to develop a broader view of Recovery.

Failure to demonstrate contrast nephrotoxicity

OBJECTIVE

We tested the hypothesis that there is no difference in the change in serum creatinine level following computed tomography (CT) between those given high osmolality contrast, low osmolality contrast and those not receiving contrast material.

DESIGN

Patients were assigned according to current radiological practice to receive one or other type of radiocontrast material or to have a scan without intravenous contrast (plain scan).

SETTING

The CT unit of Royal Newcastle Hospital, a tertiary referral institution.

PATIENTS

Of 3188 inpatients having a CT scan between June 1988 and December 1989, 1041 patients were eligible (having a first scan in "office hours" outside holiday periods, not due for imminent discharge, aged 18 years or more and not presenting to the Intensive Care Unit or with acute trauma). Twenty-five patients were excluded as baseline measures of renal function were missing and 132 subjects were lost to follow-up, leaving 884 study subjects.

INTERVENTIONS

CT scans using high osmolality, low osmolality or no contrast (plain scan).

MAIN OUTCOME MEASURE

Renal impairment as defined by a maximal increase in the serum creatinine level of greater than or equal to 50% or greater than 0.04 mmol/L from the baseline level on at least one of the subsequent four days.

RESULTS

Renal impairment was seen in 4% (12 of 292), 12% (23 of 187) and 4% (16 of 405) of patients given high osmolality, low osmolality or no contrast respectively. Age and the baseline level of serum creatinine were independent predictors of the development of renal impairment (P = 0.04 and 0.02 respectively) and those given low osmolality contrast were 3.2 times (95% confidence interval, 1.6-6.3) more likely to develop renal impairment than those given no contrast. There was no excess risk with the use of high osmolality contrast compared to no contrast (odds ratio, 1.06; 95% confidence interval, 0.5-2.3). Selection factors (sicker patients being given low osmolality contrast) are likely to have accounted for the excess risk in the low osmolality group as mortality in hospital was higher in this group than in the others. The 51 patients who developed renal impairment (cases) were matched for age, sex, type of contrast and pre-existing renal impairment with up to three controls (150 patients in total). Cases were more likely to have had a blood transfusion (odds ratio, 6.40; 95% confidence interval, 2.18-22.63) or surgery (odds ratio, 3.22; 95% confidence interval, 1.19-7.65) than controls.

CONCLUSIONS

Confounding by other factors which impair renal function is likely to explain previous suggestions of an effect of radio-contrast material on renal function. There does not appear to be a risk of renal impairment from the use of high osmolality radiocontrast material (although a small effect or an effect in particular subgroups cannot be excluded by our study). Fear of causing or exacerbating renal damage should not be a reason to use low osmolality contrast material, nor should it be a reason for with-holding contrast studies.

Lack of relationship between parity and level of carcinoembryonic antigen in women with breast cancer

Women with high parity appear to be protected against the development of breast cancer. It has been suggested that those tumours which secrete carcinoembryonic antigen (CEA) are destroyed in women who develop cell-mediated immunity to embryonic antigen at the time of pregnancy or childbirth at an early age. A study of 335 patients with breast cancer was designed to test the hypothesis that circulating levels of CEA would be lower in women with high parity and an early age at first pregnancy or live birth. CEA levels were higher if measured in the presence of tumour metastasis. There was no association between CEA levels and parity, age at first live birth, age at diagnosis or cigarette smoking. Thus we have no evidence that breast cancers which express embryonic antigens, such as CEA, are preferentially destroyed by an immune response which has arisen from embryonic inoculation during or around an early childbirth.

Rural sites benefit from link to urban center

Six-year-old Thomas Carter never knew that his risk of permanent injury was worse because he lived in Morton, in rural West Texas. But when Thomas chose to play with matches and was accidentally burned over 40 percent of his body, statistically the chances were slim that he could be saved from death or permanent injury.

Chloroquine poisoning in a child

Chloroquine poisoning in children, although infrequent, is extremely dangerous because of the narrow margin between therapeutic and toxic doses. Children clinically present with apnea, seizures, and cardiac arrhythmias. We present the case of a 12-month-old infant, the second-youngest patient reported in the US literature to die from chloroquine poisoning. A serum level of 4.4 mg/L (13.64 mumol/L) was obtained after the infant ingested only one tablet (300 mg). This establishes a new minimal lethal dose/blood level for children. Although some pediatric and adult pharmacokinetic and clinical similarities exist, the outcome is different. Pediatric mortality is 80%, whereas adult mortality is only 10%. Pediatric ingestion cases are primarily unintentional, and most adult cases are suicide attempts. Current treatment in adults includes a protocol of diazepam and epinephrine. Further studies involving children and these medications and other modalities are needed to improve survival.

Organization and expression of polygalacturonase and other ripening related genes in Ailsa Craig "Neverripe" and "Ripening inhibitor" tomato mutants

The organization and expression of ripening-related genes were investigated in normal tomato (Lycopersicon esculentum cv. Ailsa Craig) and in Neverripe (Nr) and Ripening inhibitor (rin) mutants.Hybridization studies with ripening-related cDNA clones showed that the gene for polygalacturonase (PG) is barely expressed in rin and expressed at a low level in Nr fruit. Four other genes were found to be expressed at reduced levels in rin. Exogenous ethylene was able to restore higher levels of expression of all the genes showing reduced expression in rin except that for PG. However, exogenous ethylene did not restore normal ripening in rin fruit. Analysis of chromosomal DNA by Southern blotting indicated that all the genes studied, including the PG gene, and also an upstream promoter of the PG gene, are present in the rin and Nr genomes and appear to be arranged in a similar way to those in normal tomatoes. The results are discussed in the light of the suggestion that these mutations may involve part of the regulatory apparatus leading to the expression of ripening genes such as PG.

Aromatase is concentrated in the proximal pars distalis of tilapia pituitary

Aromatase has been identified in the telostean, avian, and mammalian pituitaries, although its cellular location(s) is not yet certain. To address this question, experiments were performed in tilapia (Oreochromis mossambicus), a species which has been well characterized with respect to the intraglandular distribution of the different pituitary cell types. To estimate aromatase, glands were microdissected into rostral pars distalis (RPD), proximal pars distalis (PPD), and neurointermediate lobe (NIL) and organs were cultured in the presence of [3H]androstenedione for 16-24 hr. [3H]Estrogen products were isolated and quantified after ether extraction, hydrolysis with glucuronidase-sulfatase, thin-layer chromatography, and phenolic partition. Authentic estrone or estradiol-17 beta were produced by all pituitary regions and also by the urophyseal region of the spinal cord. Aromatase was two to five times higher in PPD than in RPD or NIL and similar to activity in adjacent hypothalamus-preoptic area (HPOA). Much lower estrogen yields were obtained in cultures of cerebellum, urophysis, and other cord regions. Since the PPD contains most of the somatotropes, these data are consistent with earlier studies implicating GH3/GH4 cell strains as an enriched enzyme source, although its presence in other cell types cannot be ruled out. The unusually high and localized aromatase in tilapia pituitary renders this species a useful model for studying the targets and functional importance of estrogen as a parahormone in the pituitary.

Identification and sequence determination of a cDNA clone for tomato pectin esterase

Cell wall softening during tomato fruit ripening is brought about through the action of a number of pectolytic enzymes. We have reported previously the cloning and characterisation of the cDNA for the major cell wall softening (degrading) enzyme, polygalacturonase [Grierson, D., Tucker, G. A., Keen, J., Ray, J., Bird, C. R. and Schuch, W. (1986) Nucleic Acids Res. 14, 8595-8603]. We have now isolated a cDNA clone for tomato pectin esterase, an enzyme also implicated in cell wall softening. Here we report the structure of this cDNA and compare it with the structure of pectin esterase derived from amino acid sequence experiments [Markovic, O. and Jornvall, H. (1986) Eur. J. Biochem. 158, 455-462]. We have used the pectin esterase cDNA clone to analyse pectin esterase gene expression during development and ripening of normal and mutant fruit.

Mesiodistal root fracture. Three case reports

Vertical root fractures present a complex diagnostic problem. Three cases of vertical root fractures are presented. In the first case, there was a mesiodistal vertical fracture with an almost intact tooth structure. In the second case, there was a mesiodistal vertical fracture with an extensive amalgam restoration and improper root canal treatment. The third case showed extensive root caries with proper root canal therapy. All of the cases resulted in periodontal defects with subsequent loss of the tooth. Diagnosis was obtained with the use of clinical, fiberoptic, and disclosing solution examinations. Histologic examination revealed pulpal canals devoid of vital tissue and filled with necrotic material, debris, neutrophils, and bacterial colonies.

Metabolism of 7,12-dimethylbenz[a]anthracene by Cunninghamella elegans

The metabolites of 7,12-dimethylbenz[a]anthracene (DMBA), a carcinogenic polycyclic aromatic hydrocarbon, in cultures of Cunninghamella elegans were isolated by high-pressure liquid chromatography and characterized by UV spectroscopy and mass spectrometry. The major metabolites were DMBA-trans-8,9-dihydrodiol and DMBA-trans-3,4-dihydrodiol. The 7-hydroxymethyl and the 12-hydroxymethyl derivatives of these dihydrodiol metabolites were also formed. The metabolic profile described in this report contrasts with those obtained in our earlier experiments in which the incubation of DMBA with Pseudomonas aeruginosa and Penicillium notatum produced no dihydrodiol metabolites but only methyl-hydroxylated metabolites.

Treatment of primary osteosarcoma with intra-arterial and intravenous high-dose methotrexate

In an effort to achieve high concentrations and prolonged exposure times, high-dose methotrexate (MTX) was administered by the intra-arterial route over 6 hours at a dose of 12.5 g/m2 to nine patients with osteosarcoma. This was followed by citrovorum factor (CF) rescue, which was initiated 12 hours after completion of the infusion (MTX-CF). The regimen achieved high local concentrations over a finite period. No toxicity was encountered. Treatment was administered at weekly intervals, during which intravenous MTX-CF was interposed if facilities for intra-arterial administration were not available. However, despite increases in local venous concentrations and exposure times, only four of nine patients (44%) responded. This is similar to responses achieved with 7.5 g/m2 (48%) with CF initiated 2 hours after completion of the infusion. Higher MTX doses, intra-arterial administration, and prolongation of cytotoxic exposure time did not confer a therapeutic advantage as opposed to "conventional" intravenous high doses.

Osteosarcoma: intra-arterial treatment of the primary tumor with cis-diammine-dichloroplatinum II (CDP). Angiographic, pathologic, and pharmacologic studies

Intra-arterial CDP was utilized to treat the primary tumor in 11 pediatric patients with osteosarcoma and in one with malignant fibrous histiocytoma. The investigation commenced with a phase I-II pilot study in four osteosarcoma patients. A dose of 150 mg/m2 was found to be safe and effective in producing a clinical response. This was followed by a definitive study in the remaining seven osteosarcoma patients and in the one malignant fibrous histiocytoma patient. The results were assessed by specific clinical, pharmacologic, radiographic and pathologic criteria. The overall response in the definitive study was 50% with two patients exhibiting total tumor destruction. The success of intra-arterial CDP was attributed to its ability to achieve high local drug concentration and tumor penetration. This was demonstrated by pharmacologic studies.

Plasma lipid levels in insulin-dependent diabetes mellitus

Because several recent reports have indicated a high incidence of hyperlipidemia in insulin-dependent juvenile diabetes, the plasma lipid levels were measured in a population of insulin-dependent diabetic patients to determine if hyperlipidemia is necessarily associated with diabetes. Only one patient had an elevated cholesterol concentration (greater than 220 mg. per deciliter) and two patients had an elevated triglyceride concentration (greater than 140 mg. per deciliter), giving an incidence of 6.4 per cent. A normal control group had an incidence of hyperlipidemia of 5.7 per cent. The mean cholesterol level (164 "/- 38 mg. per deciliter) of the diabetic population was significantly less than that of the normal control group (183 +/- 38 mg. per deciliter). The diabetic patients were divided into groups on the basis of 24-hour urinary glucose excretion and records of glycosuria. The serum triglyceride of the patients in group 4 (highest urinary glucose content and spills) was significantly elevated above three other groups with less glucosuria. Dietary history revealed that group 4 patients consumed a significantly higher percentage of fat. Cholesterol levels did not correlate with parameters of regulation of the diabetes.

Speech and lingual behavior before and after mandibular osteotomy

A procedure was applied to compare the oral behavior of five patients before and after mandibular osteotomy for correction of Class III malocclusions. It was found that observable changes in oral behavior do occur after mandibular osteotomy. Fewer errors were found in sibilant articulation, while more maladaptive lingual behaviors were found in lingual diadochokinetic tasks. Changes were also found in swallowing behaviors. Performance tasks of speech, diadochokinetics, and swallowing were recorded on audio-videotape.