Sequential evaluation of portal venous hemodynamics by Doppler ultrasound in patients with severe acute hepatitis

OBJECTIVES

Portal hypertension may develop in patients with severe acute hepatitis. Sequential changes of portal venous hemodynamics in acute hepatitis is not well understood. This study evaluated portal hemodynamic changes and prognostic values in patients with severe, acute hepatitis.

METHODS

Doppler studies, liver function tests, and virology studies were done in the inclusion, the 3rd month, and the 6th month for patients with severe, acute hepatitis. An indocyanine green clearance was done in the inclusion. Doppler portal hemodynamic studies were done in the hilar area by an average of two measurements.

RESULTS

A total of 88 consecutive patients was included. Nine of them died. On initial study, fatalities were generally older patients with more delayed indocyanine green clearance, lower portal vein velocity, lower albumin values, higher bilirubin values, longer prothrombin time, and ascites. Using stepwise logistic regression, portal blood flow and prothrombin time were the two independence prognostic factors. By multiple linear regression, portal blood flow was associated with ascites, and average portal blood velocity was associated with bilirubin. During the hospital days, transient, depressed portal blood velocities followed by a hyperdynamic stage were found in survivors. The portal vein velocity changes for fatalities either were kept at a lower level or had a declining pattern.

CONCLUSIONS

Doppler ultrasound detects portal hemodynamic changes for patients with severe, acute hepatitis. Sequential portal hemodynamic studies will be helpful for evaluating patients with severe, acute hepatitis.

Riboflavin-binding protein induces early death of chicken embryos

Maternal riboflavin-binding protein (RfBP) mediates the deposition of riboflavin in avian eggs. A strain of Single-Comb White Leghorn chicken, genetically unable to synthesize RfBP, produces eggs deficient in riboflavin. Embryos in these eggs die on or about 13 of incubation, with severe hypoglycemia and impaired fatty acid oxidation. Injection of free riboflavin prior to incubation allows these embryos to survive and hatch normally. The egg whites of eggs from the RfBP-deficient strain were injected with different relative amounts of riboflavin and RfBP to determine their effects on the developing embryo. Injection of protein-bound riboflavin resulted in a substantial number of the embryos (27%) surviving until the end of the experiment (d 19) with an average weight of 13.7 g, demonstrating that some embryos were able to use the bound riboflavin. In control groups injected with riboflavin alone, 10 of 17 embryos survived until d 19 with an average weight 18.5 g, whereas those injected with saline died between d 10 and 13 with an average weight of 3.8 g. A fourth group, injected with apo-RfBP, produced embryos with an average weight of 0.24 g. This early death suggests that the protein scavenges the small amount of riboflavin normally available to the early embryo. Further studies showed that titration of RfBP-binding sites with exogenous riboflavin lessens this effect. These studies show that although riboflavin-binding protein is essential for the deposition of riboflavin in eggs, its presence in excess can diminish the availability of riboflavin to the chicken embryo.

Age-associated mitochondrial DNA deletions in mouse skeletal muscle: comparison of different regions of the mitochondrial genome

The abundance of mitochondrial DNA (mtDNA) deletions has been shown to increase with age in a number of species and may contribute to the aging process. Estimating the total mtDNA deletion load of an individual is essential in evaluating the potential physiological impact. In this study, we compared three 5-kb regions of the mitochondrial genome: one in the major arc, one in the minor arc, and a third containing the light strand origin of replication. Through PCR analysis of mouse skeletal muscle, we have determined that not all regions produce equal numbers of age-associated deletions. There are, on average, twofold more detectable deletions in the major arc region than in the minor arc region. Deletions that result in the loss of the light strand origin of replication are rarely detected. Furthermore, the mechanism of deletion formation seems to be similar in both the major and minor arcs, with direct repeats playing an important, although not essential, role.

Gastric actinomycosis

A case of actinomycosis of the stomach in a 61-year-old woman is reported. The patient presented to the hospital with a history of epigastric pain, fatigue, poor appetite, constipation and mild fever of 20 days' duration. On physical examination, a tender mass was felt at the epigastrium. Computed tomography (CT) showed a heterogeneously enhanced mass at the posterior wall of the stomach. Upper gastrointestinal series revealed a submucosal mass at the gastric antrum. A malignant tumor was suspected and surgery was recommended. A 5 x 4 x 2 cm mass was found at the posterior wall of the distal gastric antrum. A Billroth II subtotal gastrectomy was performed. Pathologic examination revealed suppuration and sulfur granules in the indurated mass. The patient was subsequently treated with intravenous penicillin-V for 12 days and then with oral penicillin-G for 4 months. She remained well at her last follow-up appointment. Although the initial radiologic findings were nonspecific, CT was of importance in delineating the location and evaluating the extent of the lesion.

Oligomerization of endothelial nitric oxide synthase. Evidence for a dominant negative effect of truncation mutants

Nitric oxide produced by the endothelial isoform of nitric oxide synthase (ecNOS) is a key determinant of vascular tone. In contrast to other nitric oxide synthase (NOS) isoforms, which have been characterized as soluble homodimeric enzymes, ecNOS is predominantly membrane-associated, a feature that has hindered direct biochemical analyses of its oligomeric structure. We investigated ecNOS oligomerization using co-immunoprecipitation experiments in transiently transfected COS-7 cells. When COS-7 cells co-transfected with constructs encoding wild-type ecNOS and an epitope-tagged myristoylation-deficient mutant were biosynthetically labeled with [3H]myristate, the antibody to the epitope tag specifically immunoprecipitated 3H-labeled ecNOS, reflecting enzyme oligomerization. In COS-7 cells transfected with cDNAs encoding epitope-tagged truncation mutants and untagged full-length ec-NOS, the wild-type enzyme could be immunoprecipitated by the antibody to the epitope tag. Co-immunoprecipitation of ecNOS with truncation mutants documented that both N- and C-terminal domains are involved in ecNOS oligomerization. When these truncation mutants are co-expressed with wild-type ecNOS, they exert a marked dominant negative effect on enzyme activity. Since NOS oligomerization itself may be subject to dynamic modulation, the regulation of ecNOS assembly may have implications for NO signaling in the vascular wall.

Giant retroperitoneal hemangiopericytoma

Hemangiopericytomas are rare vascular tumours that are derived from pericytes. Retroperitoneal hemangiopericytomas are usually bulky but clinically silent when diagnosed because of their slow rate of growth. A 49-year-old man, who presented with only vague symptoms of abdominal fullness for several months, was found on computed tomography to have a huge well-defined mass with areas of low attenuation and well-enhanced septa. The tumour was successfully resected and was confirmed to be a malignant retroperitoneal hemangiopericytoma. It measured 30 cm in the greatest dimension. We are prompted to present this case as it is believed to be the largest tumour reported to date.

Monitoring of two hearts in one chest

A 32 year old patient with end-stage cardiomyopathy underwent heterotopic heart transplantation with a small donor heart. Monitoring of this unusual clinical setting of two hearts beating independently in one chest required special technique and scrutinous interpretation so one can differentiate donor heart from recipient heart immediately.

Dobutamine stress echocardiography predicts early wall motion improvement after elective percutaneous transluminal coronary angioplasty

In 24 patients with chronic coronary artery disease, dobutamine stress echocardiography (DSE) was performed within 2 days before and after successful elective percutaneous transluminal coronary angioplasty (PTCA) in a blinded fashion. Patients with ischemic response on DSE before PTCA had significant improvement in the global peak-dose DSE score index after PTCA (1.62 +/- 0.35 to 1.40 +/- 0.29, p < 0.001), whereas patients without ischemic response had no improvement. The positive and negative predictive values of pre-PTCA DSE on early myocardial ischemia relief after angioplasty were 93% and 80%, respectively. In patients showing contractility recruitment during low-dose dobutamine infusion in the DSE before PTCA, there was significant improvement in the global resting wall motion score index in the DSE after PTCA (1.48 +/- 0.43 to 1.34 +/- 0.33, p = 0.004), while patients without contractility recruitment showed no improvement. Again, the positive and negative predictive values of pre-PTCA DSE on early hibernation recovery following angioplasty were 80% and 89%, respectively. In conclusion, DSE in patients with chronic, stable coronary artery disease accurately predicts wall motion improvement after successful angioplasty, and the expected improvement is safely demonstrated early after the procedure.

Continuous noninvasive determination of pulsus paradoxus: a pilot study

OBJECTIVE

To evaluate two methods of continuous, noninvasive monitoring of pulsus paradoxus (PP).

METHODS

A single-subject, nonblind assessment was conducted of the ability of noninvasive monitoring techniques to measure experimentally induced PP. Variable degrees of PP were induced in a healthy adult breathing through a one-way valve to which a series of external airway resistances were added. Intra-arterial pressure (IAP), finger arterial blood pressure (FINAP), pulse oximeter pulse waveform, and chest wall motion were continuously recorded. For each resistance, PP was calculated from the IAP (PPIAP) and the FINAP (PPFINAP) recordings. PP was measured manually (PPmanual) in the opposite arm. The percentage pulse waveform decrease on inspiration (%PWDpleth) was derived from the oximeter pulse waveform. These measurements were compared with the PPIAP. Bias was assessed as the mean difference between PP measures.

RESULTS

PPFINAP was highly correlated with PPIAP (r = 0.96; 95% CI 0.93 to 0.98; p < 0.0001). There was a weak correlation between PPmanual and PPIAP (r = 0.27; 95% CI -0.05 to 0.55; p = 0.0963). The %PWDpleth correlated with PPIAP (r = 0.59, 95% CI 0.32 to 0.78; p = 0.0002). Bias was -1.515 +/- 5.6 mm Hg between PPIAP and PPFINAP; and -4.508 +/- 23.4 mm Hg between PPIAP and PPmanual.

CONCLUSION

An accurate and continuous PP can be measured noninvasively using a FINAP monitor. This method has much better agreement with IAP measurements than do manual measurements. The qualitative information provided by the oximeter pulse waveform is less accurate than that provided by the FINAP monitor, but is a potentially useful screening tool for detection of significant PP.

High levels of mitochondrial DNA deletions in skeletal muscle of old rhesus monkeys

Mitochondrial DNA (mtDNA) deletions increase in abundance with age in many tissues, however, their calculated low levels (usually < 0.1%) in samples from tissue homogenates containing thousands of cells argue against physiologic significance. Through the analysis of defined numbers of cells (skeletal muscle fibers) from rhesus monkeys, we report that the calculated abundance of specific mtDNA deletions is dependent upon the number of fibers analyzed: as the number of fibers decreases, the calculated deletion abundance increases. Also, most mtDNA deletions appear to occur in a mosaic pattern, varying from cell to cell in size, number and abundance. These data support the hypothesis that mtDNA deletions can focally accumulate to high levels contributing to declines in mass and function of aging skeletal muscle.

Isolation and analysis of nephritic-producing immune complexes in Plasmodium berghei-infected mice

A nephritic condition was developed by infecting Swiss Webster albino mice with the malarial parasite Plasmodium berghei NK 65. These animals were tested for urinary protein and the presence of circulating immune complexes using reagent strips and a polyethylene glycol (PEG) precipitation assay. The circulating immune complexes were isolated from the sera using both affinity chromatography and PEG precipitation and from the kidney by acid elution. The isolated complexes were dissociated into their individual components and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The components of the complexes were transferred to nitrocellulose sheets and probed for the presence of malarial antigens using a rabbit anti-P berghei antisera. The overall humoral response to the malarial parasite was evaluated using a radial immunodiffusion assay. The present study confirmed that the malarial-infected animals not only developed the nephritic condition (as evident by the high levels of proteinuria) but also, as indicated by the PEG assay, have the presence of high levels of circulating immune complexes in their serum. The apparent absence in the SDS gels of any abnormal protein bands followed by the inability of the Western blot to reveal any malarial antigens provides some of the strongest evidence to date that these malarial proteins are not directly involved in the circulating immune complexes believed to be responsible for producing this nephritic condition.

Rebleeding rate of various stigmata of recent hemorrhage in peptic ulcer bleeding with different severity

The stigmata of recent hemorrhage (SRH) have been used as a factor for predicting peptic ulcer rebleeding. In previous studies, the rebleeding rate of the visible vessel varied. A hypothesis had been proposed stating that the evolution of the color of the stigmata depends on the point in the healing process of the blood clot on the bleeding ulcer. This retrospective study evaluates the rebleeding rates associated with various colors of stigmata of recent hemorrhage. Of a total of 623 cases of peptic ulcer bleeding (474 male and 149 female, with a mean age of 59 years old), there were 232 gastric ulcers, 369 duodenal ulcers, and 22 stomal ulcers. Stigmata of recent hemorrhage were found in 387 cases (62%). The overall rebleeding rate for those with gastric ulcers was higher than for those with duodenal ulcers (24.2% versus 16.3%, p<0.05), especially for oozing and sentinel clots, the rebleeding rates for active bleeding, blood clots, sentinel clots, and others were 35%, 24.8%, 17%, and 11.3% respectively. The red clot of stigmata of recent hemorrhage had a slightly higher rebleeding rate than the black clot, but the difference was not statistically important. Furthermore, the 5 duodenal ulcers with white sentinel clots experienced no rebleeding. When comparing the rebleeding rates between groups with massive and minor bleeding, a significantly higher rebleeding rate was found in the massive bleeding group (50.5% versus 6.6%, p < 0.001). It can thus be seen that the different types of stigmata of recent hemorrhage represent different stages in the healing process of a bleeding ulcer. A white sentinel clot had a change of not rebleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of delayed treatment with sodium polystyrene sulfonate on serum lithium concentrations in mice

OBJECTIVES

To determine the efficacy of sodium polystyrene sulfonate (SPS) in lowering serum lithium (Li) concentrations. Specifically, to determine the effects of both different doses of SPS and different times to treatment with SPS on serum Li levels.

METHODS

The study was a controlled, single-dose murine trial of SPS on serum Li levels. Male CD-1 mice (n = 525) were given orogastric LiCl and then divided into three main treatment groups: group SPS received a single orogastric administration of SPS in a dose of 5 gm/kg body weight at either 0, 15, 30, 45, or 90 minutes after LiCl; group half-SPS received a single orogastric administration of SPS in a dose of 2.5 gm/kg body weight at times equivalent to those of group SPS; and the control group received orogastric deionized water in a volume equivalent to that of group SPS at 0, 15, 30, 45, or 90 minutes after LiCl. Subgroups of seven to ten mice in each of the four treatment groups were sacrificed at one, two, four, and eight hours after administration of LiCl, and their blood was analyzed for Li concentration.

RESULTS

1) Single doses of SPS significantly lowered serum Li concentrations; 2) this effect was dose-related; 3) the delays in administration of SPS used in this study did not significantly reduce its ability to lower serum Li concentrations; and 4) even when administered after peak serum Li concentrations had been achieved, a single dose of SPS was effective in lowering serum Li levels.

CONCLUSIONS

SPS may be efficacious in the treatment for Li toxicity under certain circumstances, even when there is delay to treatment. Additional study is warranted to further characterize the ability of SPS to alter Li kinetics.

A double-blind comparison of once-daily metoprolol controlled-release and atenolol in the treatment of Chinese patients with mild to moderate hypertension

The efficacy and tolerability of controlled-release metoprolol (metoprolol CR/ZOK), 100-200 mg, and atenolol, 50-100 mg, once daily was compared in Chinese patients with mild to moderate essential hypertension. The study was of a randomized, double-blind, two-way crossover design. The active treatment periods lasted 4 weeks each and were preceded by a 4-week placebo run-in period. The two double-blind phases were separated by a 2-week washout period on placebo. Blood pressures and heart rates were measured at rest in each 2-week visit and during exercise at the end of each treatment period. Twenty-four patients (M/F = 14/10) were valid for efficacy analysis. Their ages ranged from 39 to 68, with a mean of 53.5 years. The rest supine blood pressure and heart rate before active treatment was 160 +/- 15/106 +/- 6 mmHg and 75 +/- 14 beats/min (mean +/- SD), respectively. A responder was defined as exhibiting a supine diastolic blood pressure < or = 90 mmHg or a supine diastolic blood pressure reduction of at least 10% of the baseline level. Both agents had high response rate: 88% and 92% of all patients responded to metoprolol CR/ZOK and atenolol, respectively. Both active treatments considerably reduced resting systolic and diastolic blood pressures and heart rates as compared with baseline (p < 0.001), respectively. With controlled-release metoprolol, a more pronounced beta 1 blockade was obtained than with atenolol, which was expressed as a significant reduction in exercise-induced heart rate at the highest comparable workload compared with placebo (p < 0.05). These findings are compatible with those reported from western populations.

Success of endoscopic injection therapy in correlation with maximal one-day transfusion requirement

BACKGROUND AND STUDY AIMS

The rate of blood transfusion is related to blood flow and the diameter of the bleeding vessel. Therapeutic endoscopy is less effective in larger vessels. To determine the effect of therapeutic endoscopy with pure ethanol injection in massive peptic ulcer bleeding, we conducted a retrospective study using the maximal one-day blood requirement as an indicator of the required blood transfusion.

PATIENTS AND METHODS

The maximal one-day blood requirement was defined as the total amount of blood transfusion needed within a day to keep hemodynamics stable and hemoglobin above 8.0 g% before therapeutic endoscopy. From January 1986 to May 1993, 283 patients with high-risk signs of the stigmata of hemorrhage on endoscopy, who received pure ethanol injection therapy, were included in this study. There were 214 men and 69 women with a mean age of 58.4 years (ranging from 16 to 93 years). One hundred forty-three had gastric ulcers; 125 had duodenal ulcers; and 15 had stomal ulcers. Patients whose maximal one-day blood requirement was less than 1000 ml were assigned to Group I. Patients without, and patients with, major organ diseases whose maximal one-day blood requirement was more than 1000 ml were assigned to Group IIa and Group IIb, respectively.

RESULTS

In Group I, 87.1% attained permanent hemostasis; 51.3% in Group IIa; and 49.4% in Group IIb. Temporary hemostasis and failure rates were 8.9% and 4.8% in Group I; 14.5% and 33.8% in Group IIa; and 21.2% and 29.4% in Group IIb. The rate of permanent hemostasis was significantly lower in patients with massive bleeding (p < 0.001) but did not differ between patients with and without major organ diseases (p > 0.05).

CONCLUSION

The success rate for pure ethanol injection therapy was lower in patients with a large maximal one-day blood transfusion requirement.

Gender role identity and perceptions of Ismaili Muslim men and women

Gender roles in the Ismaili Muslim community were examined. Eighty-one Shia Imami Nizari Ismaili Muslims living in Ontario, Canada, provided demographic data and completed the Bem Sex-Role Inventory (BSRI; Bem, 1981) and the Attitudes Toward Women Scale (AWS; Spence, Helmreich, & Stapp, 1973). The results indicated that, although the Muslim women had more liberal views about gender roles than the Muslim men did, both the men and the women reported views that were liberal and comparable to those that have been reported by other Canadian samples.

Central cardiovascular effects of CPU-23, a substituted tetrahydroisoquinoline, in rats

The cardiovascular effects of intracerebroventricular (i.c.v.) injections of low doses of CPU-23, a substituted tetrahydroisoquinoline, were investigated and compared with those of nifedipine in pentobarbital-anaesthetized Sprague-Dawley rats. CPU-23, in doses of 0.2 to 0.5 mg/kg (i.c.v.), which did not elicit any significant cardiovascular responses when injected intravenously, caused a clear-cut and long-lasting decrease of mean arterial pressure (MAP) and heart rate (HR) in a dose-dependent manner. The effects of CPU-23, in a dose of 0.05 mg/kg, were similar to those of nifedipine, a prototype L-type calcium antagonist. The hypotensive effects of CPU-23 were significantly attenuated by bilateral cervical vagotomy. The results strongly suggest that a central component may be involved in the cardiovascular effects of CPU-23 and that dihydropyridine receptor sites in the brain may be involved in the central control of cardiovascular functions.

Septic acute cholecystitis

BACKGROUND

Bacteremia occurs frequently in cholangitis, but the incidence of bacteremia in acute cholecystitis has not previously been examined.

METHODS

Seventy-eight cases (46 men and 32 women; mean age, 63 +/- 10 years) of acute cholecystitis with positive blood cultures were analyzed for clinical manifestation, bacteriology, and what consequences ensued. Seventy-eight non-bacteremic cholecystitis patients, matched for age and sex, served as the control group.

RESULTS

The prevalence of bacteremia in acute cholecystitis was 7.65% (78 of 1020). A single microorganism was isolated from the blood and bile in 87.2% and 27.3%, respectively. The commonest organisms were Escherichia coli and Klebsiella pneumoniae. The source of bacteremia could be identified from the infected bile in 80% of cases. Compared with the non-bacteremia group, significant increases in liver biochemical test results (aspartate and alanine aminotransferases and bilirubin, and so forth), more complications (acute renal failure and septic shock), and higher mortality (9.0%) were found in the bacteremic group.

CONCLUSION

Acute cholecystitis is not often complicated by bacteremia, but when bacteremia is present, morbidity and death more consistently ensue.

Complement-mediated neurotoxicity is regulated by homologous restriction

The ability of beta-amyloid peptides to activate the classical complement cascade and the presence of various complement proteins including the membrane attack complex (C5b-9) on dystrophic neurites in Alzheimer's disease brains, raises the possibility that the complement system may contribute to this neurodegenerative disorder. To address this issue, we have studied the effect of complement activation on nerve growth factor (NGF)-differentiated rat pheochromocytoma PC12 cells, and on retinoic acid (RA)-differentiated human neuroblastoma SH-SY5Y cells. Although incubation of both cell types with human serum resulted in activation of complement, as indicated by iC3b formation, only PC12 but not SH-SY5Y cells were killed by human serum treatment. In contrast, heat-inactivated serum (56 degrees C, 45 min) was not neurotoxic. On SH-SY5Y cells, both PCR amplification and immunocytochemistry demonstrated the presence of CD59, a glycosylphosphatidylinositol-anchored protein that restricts homologous complement activation by inhibiting the formation of the membrane attack complex. The presence of CD59 probably accounts for the inability of human complement to lyse the human cell lines. Indeed, removal of glycosylphosphatidylinositol (GPI)-anchored proteins with phosphatidylinositol-specific phospholipase C (PI-PLC) rendered SH-SY5Y cells vulnerable to complement attack and eventually led to serum-medicated cell death. Reconstituted C5b-9 was also toxic to both PC12 and PI-PLC-pretreated SH-SY5Y cells. These observations suggest that complement activation can cause neuronal cell death and that this process is regulated by homologous restriction.

Gastric leiomyosarcoma: a clinicopathological review

OBJECTIVE

To report our experience of eight patients with primary gastric leiomyosarcoma.

DESIGN

Retrospective study.

SETTING

Teaching hospital, Taiwan.

SUBJECTS

8 patients who presented with primary gastric leiomyosarcoma between 1986 and 1990.

MAIN OUTCOME MEASURES

Endoscopic, radiological, and histopathological features, DNA ploidy, and outcome.

RESULTS

Abdominal pain and gastrointestinal bleeding were the most common presenting symptoms. In 5 of the 7 patients who had endoscopy preoperatively a diagnosis of submucosal tumour was made, but a definite diagnosis of leiomyosarcoma was made in only 3. A provisional diagnosis of leiomyosarcoma was made in 3 of the 4 patients who had computed tomography. All patients underwent some form of gastric resection ranging from palliative resection to total gastrectomy. Patients in whom the tumour had invaded adjacent organs had a poor prognosis. Histopathological grading of tumours correlated well with DNA ploidy.

CONCLUSION

Both histopathological grading and DNA ploidy could be helpful objective prognostic criteria in patients with primary gastric leiomyosarcoma.

Total knee arthroplasty after patellectomy

We compared the outcome of total knee arthroplasty in 19 patients who had had previous patellectomy with the results in a matched series of arthroplasties performed on knees in which the patella was intact. The mean follow-up was 63 months (21 to 114). In the study group, the outcome was poor in five patients. There was instability in the coronal plane in three patients and persistent pain in four. Three supracondylar fractures occurred. The overall complication rate was 36%. In the control group, pain was relieved in every case and there were no complications. Total knee arthroplasty has a higher complication rate and inferior results if the knee has undergone prior patellectomy.

Total knee arthroplasty after patellectomy

We compared the outcome of total knee arthroplasty in 19 patients who had had previous patellectomy with the results in a matched series of arthroplasties performed on knees in which the patella was intact. The mean follow-up was 63 months (21 to 114). In the study group, the outcome was poor in five patients. There was instability in the coronal plane in three patients and persistent pain in four. Three supracondylar fractures occurred. The overall complication rate was 36%. In the control group, pain was relieved in every case and there were no complications. Total knee arthroplasty has a higher complication rate and inferior results if the knee has undergone prior patellectomy.

cAMP is not involved in interleukin-1-induced interleukin-6 release from human astrocytoma cells

We have previously shown that activation of the phosphatidyl-inositol/phospholipase C pathway could induce interleukin 6 (IL-6) release from U373MG human astrocytomes cells. We also found that, although interleukin 1 beta (IL-1 beta) did not activate phosphatidy-linositol turnover, it induced, a robust release of IL-6. In the present study, we examined the role of adenylate cyclase/cyclic 3',5'-adenosine monophosphate (cAMP) pathway in IL-6 release. Agents which mimicked (dibutyryl cAMP) or stimulated (isoproterenol and forskolin) cAMP formation were found to induce IL-6 release and their effects could be potentiated by 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor. On the other hand, in spite of its robust action on IL-6 release, IL-1 beta did not stimulate cAMP formation. Other possible signal transduction mechanisms involved in IL-1 beta-induced IL-6 release are discussed.

Regulation of the release of interleukin-6 from human astrocytoma cells

Recent evidence suggests that the level of interleukin-6 (IL-6) is elevated in Alzheimer's disease (AD) brains. IL-6 is produced by reactive glial cells and could potentially affect neuronal survival. Understanding the biochemical mechanism that regulates the production and release of IL-6 by astrocytic cells may help to identify potential targets for therapeutic intervention in AD. In the present study, glial fibrillary acidic protein-positive human U373MG astrocytoma cells were used as a model of reactive astrocytes. Production of IL-6 in response to drug treatment was monitored with an ELISA assay. Histamine (1-100 microM), substance P (SP; 1-100 nM), and human interleukin-1 beta (IL-1 beta; 1-30 pM) stimulated the release of IL-6 in a time- and concentration-dependent manner, with EC50 values of 4.5 microM, 8 nM, and 4.5 pM, respectively. The respective effects of histamine, SP, and IL-1 beta were effectively blocked by the histamine H1, SP, and IL-1 receptor antagonists, supporting a receptor-mediated event for these agents. Both histamine and SP enhanced the formation of inositol phosphates and increase intracellular calcium levels, suggesting that the phosphatidylinositol bisphosphate/protein kinase C pathway may be involved in the IL-6 release process. Indeed, phorbol 12-myristate 13-acetate, a protein kinase C activator, also evoked IL-6 release from the U373MG cells. On the other hand, IL-1 beta, which produces a much more robust release of IL-6 than histamine or SP, has no effect on inositol phosphate formation or intracellular calcium levels.(ABSTRACT TRUNCATED AT 250 WORDS)