Interrelation between nitric oxide and endothelin-1 in an experimental acute hypoxia in rats and its intervention

OBJECTIVES

To study the interrelation between nitric oxide (NO) and endothelin-1 (ET1) in experimental acute hypoxic rats, and to evaluate the mechanism of acute hypoxic pulmonary hypertension affected by NO and ET1 and its intervention.

METHODS

Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemical staining method, Griess biochemical assay and radioimmune assay were applied to investigate the changes of nitric oxide syntheses (NOS), NO and ET1 in normal, hypoxic, and L-Arginine (L-Arg) and dexamethasone treated hypoxic rats.

RESULTS

In normal rats, the NOS stain was localized in pulmonary vascular endothelium, and in the hypoxic rats, the activity of NOS was significantly lower. The level of plasma NO was significantly lower during acute hypoxia, but L-Arg as well as dexamethasone could prevent the drop of plasma NO. The level of plasma ET1 rose up significantly in the acute hypoxic rats, but after L-Arg therapy, it was significantly reduced, however, dexamethasone could not affect plasma ET1. The level of plasma cyclic guanosine monophosphate (cGMP) was significantly lower in the acute hypoxic rats, and L-Arg could prevent the drop of plasma cGMP, but dexamethasone could not prevent the drop of plasma cGMP.

CONCLUSIONS

NO and ET1 may modulate hypoxic pulmonary hypertension and acute hypoxia can result in acute hypoxic pulmonary hypertension. L-Arg can reverse the acute hypoxic pulmonary hypertension. Further study is needed if dexamethasone is beneficial in acute hypoxic diseases. NO may play an important role in physiology of the lung and acute hypoxic diseases.

Potent inhibitors of protein farnesyltransferase: heteroarenes as cysteine replacements

Synthesis and biological evaluation of heteroarenes as reduced cysteine replacements are described. Of the heteroaryl groups examined with respect to FT inhibitor FTI-276 (1), pyridyl was the replacement found to be most effective. Substitutions at C4 of the pyridyl moiety did not affect the in vitro activity. Compound 9a was found to have moderate in vivo bioavailability.

[Expression of endothelial nitric oxide synthase mRNA in human placenta]

OBJECTIVE

To determine the localization and type of nitric oxide synthase in human placenta.

METHODS

By polymerase chain reaction and in situ hybridization. The eNOS mRNA expression was observed in 10 cases of human normal term placenta and cord.

RESULTS

In human normal term placenta, positive staining of eNOS was evident in the syncytiotrophoblast and the endothelium of umbilical artery and vein, positive staining also presented in the endothelium of stem villous vessels, but it was absent in the endothelium of terminal villous capillary.

CONCLUSION

eNOS is present in syncytiotrophoblast and endothelium of stem villi vessels, and it can synthesize nitric oxide which results in the increase of nitric oxide in pregnancy.

Pregnenolone sulfate and dehydroepiandrosterone sulfate inhibit GABA-gated chloride currents in Xenopus oocytes expressing picrotoxin-insensitive GABA(A) receptors

We examined the effects of picrotoxinin, pregnenolone sulfate (PS) and dehydroepiandrosterone sulfate (DHEAS) on gamma-aminobutyric acid (GABA) responses in Xenopus oocytes injected with wild type alpha1, beta2 and gamma2 GABA(A) receptor subunits and in oocytes injected with wild type alpha1 and beta2 subunits and a mutated gamma2 subunit that eliminates picrotoxin sensitivity. All three agents inhibited GABA currents in oocytes injected with wild type subunits. Oocytes injected with the mutated gamma2 subunit showed no inhibition of GABA responses by picrotoxinin at concentrations up to 100 microM. PS and DHEAS inhibited GABA currents at similar concentrations in both sets of oocytes. These results indicate that PS and DHEAS do not require a functional picrotoxin site for inhibition of GABA responses.

Family history characteristics, tumor microsatellite instability and germline MSH2 and MLH1 mutations in hereditary colorectal cancer

Recent characterization of the molecular genetic basis of hereditary nonpolyposis colorectal cancer provides an important opportunity for identification of individuals and their families with germline mutations in mismatch repair genes. Cancer family history criteria that accurately define hereditary colorectal cancer are necessary for cost-effective testing for germline mutations in mismatch repair genes. The present report describes the results of analysis of 33 colorectal cancer cases/families that satisfy our modified family history criteria (Mount Sinai criteria) for colorectal cancer. Fourteen of these families met the more stringent Amsterdam criteria. Germline MSH2 and MLH1 mutations were identified by the reverse transcription-polymerase chain reaction and the protein truncation test, and confirmed by sequencing. Microsatellite instability analysis was performed on available tumors from affected patients. MSH2 or MLH1 mutations were detected in 8 of 14 Amsterdam criteria families and in 5 of the remaining 19 cases/families that only satisfied the Mount Sinai criteria. Three of the latter families had features of the Muir-Torre syndrome. A high level of microsatellite instability (MSI-H) was detected in almost all (16/18) colorectal cancers from individuals with MSH2 and MLH1 mutations, and infrequently (1/21) in colorectal cancer specimens from cases without detectable mutations. Families with germline MSH2 and MLH1 mutations tended to have individuals affected at younger ages and with multiple tumors. The Amsterdam criteria are useful, but not sufficient, for detecting hereditary colorectal cancer families with germline MSH2 and MLH1 mutations, since a proportion of cases and families with mutations in mismatch repair genes will be missed. Further development of cancer family history criteria are needed, using unbiased prospectively collected cases, to define more accurately those who will benefit from MSH2 and MLH1 mutation analysis.

[Study on relationship between Deficiency Syndrome of TCM and the biological behavior in patients of esophageal carcinoma]

OBJECTIVE

To investigate the relation between Deficiency Syndrome (DS) of TCM and the invading depth, lymphnode metastasis, TNM stage and prognosis prediction of esophageal carcinoma.

METHODS

According to Syndrome Differentiation of TCM, 101 patients of esophageal carcinoma were evaluated before operation and divided into two groups, the DS group and the non-DS group.

RESULTS

Thirty-eight cases in the 101 patients were DS, among them, 14 were Qi-Deficiency, 10 Yin-Deficiency, 10 Qi-Yin Deficiency, 2 Qi- and blood Deficiency, 1 Yang-Deficiency and 1 Yin-Yang Deficiency. There were significant differences between the DS group and non-DS group in the invading depth (deeper in DS), metastasis of lymphnode (severer in DS) and TNM stage (later in DS) of esphageal carcinoma, (P < 0.05).

CONCLUSION

There is a significant relation between DS and the biological behavior of esophageal carcinoma. The prognosis of DS patients is poorer than that of the non-DS patients.

A seven-transmembrane, G protein-coupled receptor, FPRL1, mediates the chemotactic activity of serum amyloid A for human phagocytic cells

We have previously reported (Badolato, R., J.M. Wang, W.J. Murphy, A. R. Lloyd, D.F. Michiel, L.L. Bausserman, D.J. Kelvin, and J.J. Oppenheim. 1994. J. Exp. Med. 180:203; Xu, L., R. Badolato, W.J. Murphy, D.L. Longo, M. Anver, S. Hale, J.J. Oppenheim, and J.M. Wang. 1995. J. Immunol. 155:1184.) that the acute phase protein serum amyloid A (SAA) is a potent chemoattractant for human leukocytes in vitro and mouse phagocytes in vivo. To identify the signaling mechanisms, we evaluated patterns of cross-desensitization between SAA and other leukocyte chemoattractants. We found that the chemotactic bacterial peptide, N-formyl- methionyl-leucyl-phenylalanine (fMLP), was able to specifically attenuate Ca2+ mobilization in human phagocytes induced by SAA, but only at very high concentrations, suggesting that SAA uses a low affinity fMLP receptor. Here we demonstrate that SAA selectively induced Ca2+ mobilization and migration of HEK cells expressing FPRL1, a human seven-transmembrane domain phagocyte receptor with low affinity for fMLP, and high affinity for lipoxin A4. Furthermore, radiolabeled SAA specifically bound to human phagocytes and FPRL1-transfected 293 cells. In contrast, SAA was not a ligand or agonist for FPR, the high affinity fMLP receptor. Thus, SAA is the first chemotactic ligand identified for FPRL1. Our results suggest that FPRL1 mediates phagocyte migration in response to SAA.

[Expression of Schistosoma japonicun fatty acid binding protein gene in silkworm cells and larvae]

AIM

To express the fatty acid binding protein (Sj14FABP) gene of Schistosoma japonicun in the silkworm cells and larvae.

METHODS

A 600 bp DNA fragment containing Sj14FABP gene was cloned into baculovirus transfer vector of pBacPAK His1 to construct recombinant transfer vector Sj14-pBac PAK His1. Coinfection was accomplished with this vector and Bombyx mori nuclear polyhedrosis virus (BmNPV) DNA in BmN cells. The recombinant virus of Bm-Sj14 was screened using dot-blotting. The BmN cells and silkworm larvae were infected with Bm-Sj14 to express Sj14FABF gene. Western blotting and ELISA were used to identify the antigenicity of the recombinant protein.

RESULTS

Sj14FABP gene was successfully expressed in the BmN cells and silkworm larvae infected with Bm-Sj14. The product was a 18 kDa fusion protein. The yield in BmN cells was about 100 micrograms/1 x 10(6) cells and 33 micrograms/ml cell supernatant. In silkworm larvae, the product yield was 4 mg/ml haemolymph as well as 4.6 mg/g silkworm tissue. The recombinant protein could be recognized by Western blotting and ELISA using the sera from mice immunized with SWAP.

CONCLUSION

Sj14FABP gene has been successfully expressed in BmNPV system and the product has high antigenicity.

A comparative study on the effects of low dose of tPA and different regimens of intravenous urokinase in acute myocardial infarction

OBJECTIVE

To compare the effects of low dose of recombinant tissue-type plasminogen activator (tPA) with those of conventional dose of urokinase (UK) and assess the influence of different regimens of intravenous UK in patients with acute myocardial infarction (AMI).

METHODS

Eighty patients with AMI were randomized to 50 mg of tPA (Group I; n = 26) using an accelerating approach or 1.0-1.5 million U of UK (Group II; n = 54). UK was administered as a single bolus injection of whole dose (Group IIa; n = 26) or half dose bolus injection followed by half dose infusion (Group IIb; n = 28). All patients underwent coronary arteriography 90 min after the initiation of intravenous thrombolysis, and the infarct-related coronary artery (IRA) patency was evaluated. Cardiac events during hospitalization were recorded and predischarge left ventricular function was determined by two-dimensional echocardiography.

RESULTS

The IRA patency rate was significantly higher in Group I (88.4%) than in Group II (53.7%) (P < 0.01). Group I patients had less cardiac events during hospitalization (11.5% vs 33.3%) and greater improvement in left ventricular function than Group II patients. However, these angiographic, left ventricular functional and prognostic parameters did not significantly differ between Group IIa and Group IIb.

CONCLUSIONS

Thrombolysis after AMI with low dose of intravenous tPA exerts better angiographic and clinical effects than that with conventional dose of UK. The thrombolytic effects of UK were not affected by different regimens of intravenous administration of the agent.

Effect of nitrous oxide on excitatory and inhibitory synaptic transmission in hippocampal cultures

Nitrous oxide (N2O; laughing gas) has been a widely used anesthetic/analgesic since the 19th century, although its cellular mechanism of action is not understood. Here we characterize the effects of N2O on excitatory and inhibitory synaptic transmission in microcultures of rat hippocampal neurons, a preparation in which anesthetic effects on monosynaptic communication can be examined in a setting free of polysynaptic network variables. Eighty percent N2O occludes peak NMDA receptor-mediated (NMDAR) excitatory autaptic currents (EACs) with no effect on the NMDAR EAC decay time course. N2O also mildly depresses AMPA receptor-mediated (AMPAR) EACs. We find that N2O inhibits both NMDA and non-NMDA receptor-mediated responses to exogenous agonist. The postsynaptic blockade of NMDA receptors exhibits slight apparent voltage dependence, whereas the blockade of AMPA receptors is not voltage dependent. Although the degree of ketamine and Mg2+ blockade of NMDA-induced responses is dependent on permeant ion concentration, the degree of N2O blockade is not. We also observe a slight and variable prolongation of GABAA receptor-mediated (GABAR) postsynaptic currents likely caused by previously reported effects of N2O on GABAA receptors. Despite the effects of N2O on both NMDA and non-NMDA ionotropic receptors, glial glutamate transporter currents and metabotropic glutamate receptor-mediated synaptic depression are not affected. Paired-pulse depression, the frequency of spontaneous miniature excitatory synaptic currents, and high-voltage-activated calcium currents are not affected by N2O. Our results suggest that the effects of N2O on synaptic transmission are confined to postsynaptic targets.

[The changes of pancreatic function after cardiopulmonary bypass]

OBJECTIVE

To evaluate the changes of endocrine and exocrine pancreatic function in patients who underwent heart valve replacement under cardiopulmonary bypass (CPB) in order to optimally conside clinical management perioperatively.

METHOD

Sixteen patients with heart valve disease were selected. Serum glucose, lactate, insulin, C peptide, amylase and lipase were measured.

RESULT

Hyperglycemia and hyperlactacemia were noted after CPB and peaked at 19:00 on the operative day. Their changes were correctly correlated. Serum glucose and lactate returned to the baseline level on the third postoperative day. The average level of serum insulin were normal, but higher on the third postoperative day. However, the level of serum C peptide was higher than the baseline. It doubled the baseline level at 19:00 on the operative day. The average level of serum amylase and lipase was normal, except the higher level of serum lipase on the fourth postoperative day. In our group, 12 patients had normal serum amylase level perioperatively, and 4 increased serum amylase level (25%), among them 2 patients accompanied with hyperlipasimia (16%). There were 8 patients with hyperlipasimia (50%).

CONCLUSION

The endocrine and exocrine pancreatic functions were influenced by CPB and did produce pathophysiologic changes.

Lack of desensitization and enhanced efficiency of calcium channel promoter in conscious dogs with heart failure

The goal of this study was to compare responses to a calcium promoter, BAY y 5959, and dobutamine (Dob) in heart failure (HF). Dogs (n = 9) were chronically instrumented and studied in the conscious state before and after pacing-induced HF. In the control state, BAY y 5959 (20 microgram. kg-1. min-1) increased the first derivative of left ventricular (LV) pressure (dP/dt) by 83 +/- 8% and mean arterial pressure (MAP) by 8 +/- 2% and decreased heart rate (HR) by 30 +/- 3%. With Dob (10 microgram. kg-1. min-1) LV dP/dt rose similarly (+80 +/- 6%), but HR also rose (+25 +/- 4%) (P < 0.05 vs. BAY y 5959). After HF developed, BAY y 5959 still increased LV dP/dt by 108 +/- 8% and MAP by 21 +/- 2% and decreased HR by 28 +/- 4%, whereas Dob increased LV dP/dt by only 50 +/- 7% (P < 0.05 vs. BAY y 5959) and MAP by 7 +/- 3%, and HR did not change (+3 +/- 3%) (P < 0.05 vs. BAY y 5959). In HF, cardiac work increased more (P < 0. 05) with BAY y 5959 (+105 +/- 13%) compared with Dob (+47 +/- 11%), yet myocardial oxygen consumption increased similarly with the two drugs. Accordingly, mechanical efficiency increased more (P < 0.05) with BAY y 5959 (+73 +/- 14%) than with Dob (+17 +/- 12%). These data indicate that 1) increases in contractility mediated directly by Ca2+ are relatively resistant to desensitization in HF; and 2) the calcium-channel promoter can produce increases in myocardial contractility and cardiac work similar to those of Dob at a significantly lower oxygen cost, thereby enhancing mechanical efficiency in HF.

Metabotropic and ionotropic glutamate receptors regulate calcium channel currents in salamander retinal ganglion cells

1. Glutamate suppressed high-voltage-activated barium currents (IBa, HVA) in tiger salamander retinal ganglion cells. Both ionotropic (iGluR) and metabotropic (mGluR) receptors contributed to this calcium channel inhibition. 2. Trans-ACPD (1-aminocyclopentane-trans-1S,3R-dicarboxylic acid), a broad-spectrum metabotropic glutamate receptor agonist, suppressed a dihydropyridine-sensitive barium current. Kainate, an ionotropic glutamate receptor agonist, reduced an omega-conotoxin GVIA-sensitive current. 3. The relative effectiveness of selective agonists indicated that the predominant metabotropic receptor was the L-2-amino-4-phosphonobutyrate (L-AP4)-sensitive, group III receptor. This receptor reversed the action of forskolin, but this was not responsible for calcium channel suppression. l-AP4 raised internal calcium concentration. Antagonists of phospholipase C, inositol trisphosphate (IP3) receptors and ryanodine receptors inhibited the action of metabotropic agonists, indicating that group III receptor transduction was linked to this pathway. 4. The action of kainate was partially suppressed by BAPTA, by calmodulin antagonists and by blockers of calmodulin-dependent phosphatase. Suppression by kainate of the calcium channel current was more rapid when calcium was the charge carrier, instead of barium. The results indicate that calcium influx through kainate-sensitive glutamate receptors can activate calmodulin, which stimulates phosphatases that may directly suppress voltage-sensitive calcium channels. 5. Thus, ionotropic and metabotropic glutamate receptors inhibit distinct calcium channels. They could act synergistically, since both increase internal calcium. These pathways provide negative feedback that can reduce calcium influx when ganglion cells are depolarized.

Production and testing of Schistosoma japonicum candidate vaccine antigens in the natural ovine host

The objectives of this work were to clone and express Chinese strain Schistosoma japonicum antigens and evaluate their immunogenicity and protective efficacy in the natural ovine host in China. Recombinant antigens selected for testing were: isoforms of glutathione S-transferase Sj28GST and Sj26GST; the large hydrophilic domain of Sj23, the homologue of the protective S. mansoni membrane antigen Sm23; and a 3' fragment of S. japonicum paramyosin. In addition, Chinese strain S. japonicum native paramyosin and GST were purified and used for vaccination. Antigens were co-administered with Freund's adjuvants or BCG. We also examined the effects of co-administration of native unfractionated GSTs with keyhole limpet haemocyanin (KLH), which shares a cross-reactive protective epitope with schistosomes. These are the first side-by-side comparisons of candidate defined-antigen schistosomiasis vaccines in a natural host. Significant partial protection was obtained with each of the antigens tested. Less protection was obtained with a recombinant fragment of S. japonicum paramyosin compared with native paramyosin. Co-administration of native GST and KLH was no more effective than vaccination with either antigen alone. Although encouraging levels of protection against S. japonicum were demonstrated using each of these antigens, further work is needed to optimise vaccine delivery and vaccination schedules.

Amino acid residues in Std1 protein required for induction of SUC2 transcription are also required for suppression of TBPDelta57 growth defect in Saccharomyces cerevisiae

The STD1 gene of Saccharomyces cerevisiae was isolated independently as a multicopy suppressor of a dominant negative mutation in the TATA-binding protein and of a mutation in the Snf1/Snf4 kinase complex, suggesting that Std1 might couple the Snf1 kinase signaling pathway to the transcriptional machinery. In order to identify the protein domains that specify these activities of the Std1 protein, a plasmid library of randomly mutagenized STD1 genes was screened for loss of function alleles using complementation of the raffinose growth defect of a std1-, mth1- strain as an assay. One missense allele (P236S) with complete loss of function at 30 degreesC and four missense alleles (L173F, E225K, S269L and E274K) that conferred a temperature sensitive phenotype were identified. The C-terminal 20 residues of Std1 were essential for SUC2 derepression, whereas the deletion of the N-terminal 96 residues did not affect SUC2 gene induction. Std1 mutants that lost the ability to induce SUC2, were also unable to suppress the growth defect caused by the expression of the dominant negative TBPDelta57 protein, suggesting that these two genetic screens may be detecting the same biological activity.

[Subxiphoid pericardial window drainage in the management of large pericardial effusions]

OBJECTIVE

To choose a safe, effective, minimum invasive procedure for treatment of patients with a large pericardial effusion and cardiac tamponade.

METHODS

Retrospective analysis of 30 cases with large pericardial effusion or cardiac tamponade diagnosed by echocardiography during four years (1993-1997). The subxiphoid pericardial window drainage and pericardial tissue biopsy was performed.

RESULTS

The symptoms were improved immediately following the drainage. The drainage volume during operation was 200-2,000 ml, and postoperation was 0-2,000 ml. The drainage tube was kept in position for average of 5.6 days. With the echocardiography follow up, the pericardial effusion disappeared or remained only minimum fluid in 96.7% of the patients. The complications happened in 6 cases. The 30-days mortality was 6.7%.

CONCLUSIONS

The subxiphoid pericardial window drainage procedure is the first choice for a safe, effective, minimal invasive and easy to do procedure for the patients with a large pericardial effusions or cardiac tamponade.

[Clinical analysis of postoperative radiotherapy for stage I endometrial cancer]

OBJECTIVE

To evaluate the role and complications of adjuvant radiotherapy for stage I endometrial cancer after surgery.

METHODS

From May, 1986 to December, 1995, 20 patients with stage I endometrial cancer received total abdominal hysterectomy with bilateral salpingo-oophorectomy(TAH/BSO), and additional pelvic lymph node dissection in 5 cases. Most of the patients received radio therapy in 2-4 weeks after surgery. The radiation fields included pelvic lymph nodes with a total dose of 40-50 Gy.

RESULTS

All the patients had survived for 10 years. Only one patient developed distant metastases. Acute radiation reaction was observed in all patients. Late radiation-induced damage occured in six patients and was severe in two.

CONCLUSION

Postoperative radiotherapy in the management of stage I endometrial cancer is beneficial for the controal of local recurrence but has relatively high frequency of late radiation injury.

Cyclopentanedi- and tricarboxylic acids as squalene synthase inhibitors: syntheses and evaluation

Based on earlier lead squalene synthase inhibitor A-87049 (3) and zaragozic acids, a series of cyclopentanedi- and tricarboxylic acids were synthesized and evaluated against the enzyme. Some exhibited good potency and SAR revealed the importance of conformation and substitution pattern of these synthetic inhibitors.

[The changes of maternal and umbilical serum nitric oxide in patients with pregnancy induced hypertension]

OBJECTIVE

To determine whether levels of maternal and umbilical serum nitric oxide (NO) were changed in patients with pregnancy induced hypertension (PIH).

METHODS

40 women with PIH, 40 normal late trimester pregnant women and 20 nonpregnant women were studied. Maternal venous blood were collected from all the cases and umbilical venous blood were collected from 28 of the first two groups respectively. Serum NO2-/NO3-, the endproducts of NO, were measured with the Griess reaction after reduction with nitrate reductase.

RESULTS

The mean NO2-/NO3- in maternal venous serum were 23.30 +/- 5.60 mumol/L in nonpregnant group, 26.42 +/- 4.54 mumol/L in normal pregnant group and 32.58 +/- 5.06 mumol/L in PIH group. Umbilical serum NO2-/NO3- were 12.26 +/- 4.91 mumol/L in normotensive groups and 14.64 +/- 3.90 mumol/L in PIH group. Maternal serum NO2-/NO3- in nonpregnant group were lower than that both in normal pregnant group (P < 0.05) and in PIH group (P < 0.01). Compared with the normotensive group, maternal serum NO2-/NO3- in PIH group was significantly higher (P < 0.01), while significantly higher serum NO2-/NO3- were also found in umbilical venous blood in PIH group (P < 0.05). There were no correlations between serum NO2-/NO3- level and blood pressure or birth weight. The total nitrite levels in fetal circulation was lower than that in maternal circulation in both pregnant groups (P < 0.01).

CONCLUSION

Total nitrites are increased both in maternal and fetal circulation in PIH. The result indicates that the increase of NO may be secondary compensative reaction in PIH.

Biodegradation in vitro and retention in the rabbit eye of crosslinked poly(1-vinyl-2-pyrrolidinone) hydrogel as a vitreous substitute

To elucidate the relatively short retention of crosslinked poly(1-vinyl-2-pyrrolidinone) hydrogels in the eye when used as potential vitreous substitutes, a 14C-labeled hydrogel was produced and subjected to both in vitro biodegradation assays and in vivo experiments. The polymer was synthesized by the free-radical copolymerization of 99% 1-vinyl-2-pyrrolidinone with 1% 14C-methyl methacrylate in the presence of ethylene glycol dimethacrylate (0.1%) as crosslinking agent. The in vitro protocol for assessing the biodegradation included the incubation of hydrogel with hydrolases (trypsin or collagenase), followed by examination of changes in its physical characteristics and by monitoring its residual radioactivity, as well as by detection of possible degradation products. Within the maximum duration of experiments (4 weeks), none of the procedures indicated biodegradation of polymer. The hydrogel was also injected into the vitreous humor of rabbits and followed up to 4 weeks. Residual radioactivity measurements of the vitreous contents indicated that 50% of the polymer was removed by the end of this period. Histopathologic examination revealed cell infiltrates of the mononuclear phagocyte system in both vitreous and retinal tissue. A possible phagocyte-mediated mechanism for the dissipation of hydrogel is discussed.

Cardiac protection by long-term treatment with captopril in patients with acute myocardial infarction

OBJECTIVES

To assess the effects of long-term angiotensin-converting enzyme (ACE) inhibitor treatment with captopril on cardiac function in acute myocardial infarction (AMI).

METHODS

One hundred and one patients with AMI who were admitted to hospital within 72 hours of the onset of symptoms with no cardiogenic shock were randomly allocated to captopril (n = 52; group I) and conventional treatment (n = 49; group II). Left ventricular (LV) systolic performance and diastolic transmitral flow velocity profiles were assessed by Doppler echocardiography at admission (1.2 +/- 1.1 days), before discharge (27 +/- 10 days) and during follow-up (363 +/- 31 days).

RESULTS

At one year follow-up, in group I LV end-diastolic volume decreased, and ejection fraction increased due to a disproportionate decrease in end-systolic volume. The incidence of cardiac dilatation was reduced. LV early diastolic filling velocity (E) increased and late atrial filling velocity (A) decreased, resulting in an elevation of E/A ratio. However, the mean values of LV systolic and diastolic functional parameters were unchanged in group II.

CONCLUSIONS

Long-term treatment with captopril exerts a beneficial effect on cardiac protection for patients with AMI.

Effect of crystal seeding on the hydration of calcium phosphate cement

In this paper, the effect of crystal seeding on the hydration of calcium phosphate cement (CPC) has been carefully investigated. The setting time of the CPC slurry not containing any crystal seeds was 150 min, while the setting time for the specimen containing 5 wt% low crystallinity hydroxyapatite used as a crystal seed was 7 min. This improvement in the setting time was due to HAP serving as a substrate for heterogeneous nucleation which accelerated nucleation. In addition, the compressive strength of the specimen containing the crystal seeding was deduced and we report values different from those previously reported in the literature. The calorimetric curve indicated that crystal seeding could reduce the induction period. A.c. impedance spectroscopy revealed that at the beginning of hydration, the rate of reaction increased and also that the mean diameter and porosity decreased as the seed content increased. At the end of the hydration reaction the situation was changed with the mean diameter and porosity in the sample without any seeds being a minimum, which indicated that the compressive strength was a maximum. This result could be explained by the dissolution and reprecipitation of small hydration products produced by the high rate of reaction produced by the introduction of the crystal seeds.

Defective endogenous nitric oxide-mediated modulation of cellular respiration in canine skeletal muscle after the development of heart failure

BACKGROUND

It is well documented that nitric oxide (NO) suppresses the function of a number of mitochondrial enzymes. Our recent studies found that endogenous NO may play an important role in the modulation of tissue oxygen (O2) consumption and cellular respiration both in vitro and in vivo.

METHODS

Tissue O2 consumption was measured by a Clark-type O2 electrode at 37 degrees C in freshly isolated skeletal muscle segments from the accessory head of the triceps brachii (90% type I muscle fiber) and extensor carpi radialis (86% type II muscle fiber) from normal dogs and dogs with tachycardia-induced heart failure.

RESULTS

S-nitroso-N-acetylpenicillamine (SNAP), carbachol, and bradykinin at doses of 10(-7) to 10(-4) mol/L concentration significantly suppressed tissue O2 consumption both in the absence and presence of 2,4-dinitrophenol (1 mmol/L), a mitochondrial uncoupler. These effects were not significantly different in the accessory head of the triceps brachii (90% type I muscle fiber) and extensor carpi radialis (86% type II muscle fiber). The effects of carbachol and bradykinin but not SNAP were attenuated by NG-nitro-L-arginine (10(-4) mol/L), indicating inhibition of the formation of endogenous NO. The inhibitory effect on tissue O2 consumption in response to carbachol and bradykinin became significantly smaller in skeletal muscle from dogs with pacing-induced heart failure, but the effects of SNAP were unchanged.

CONCLUSIONS

Endogenous NO released from microvascular endothelium may play an important physiologic role in the modulation of cellular respiration in skeletal muscle, and the loss of this regulatory function may contribute to peripheral metabolic disorders and poor exercise tolerance during heart failure.

Sestamibi scanning is inadequate for directing unilateral neck exploration for first-time parathyroidectomy

OBJECTIVE

To determine whether technetium Tc 99m sestamibi scanning is accurate enough to allow surgeons to perform unilateral neck exploration for first-time parathyroidectomy in patients with primary hyperparathyroidism.

DESIGN

Retrospective review.

SETTING

University tertiary care center.

PATIENTS

Forty patients with primary hyperparathyroidism who underwent sestamibi scanning before first-time parathyroidectomy, of whom 28 had single adenomas, 9 had multiple adenomas, and 3 had hyperplasia.

INTERVENTIONS

All 40 patients underwent bilateral neck exploration with identification of 4 parathyroid glands.

MAIN OUTCOME MEASURES

We compared the results of preoperative sestamibi scanning with operative and histologic findings. We then used these data to calculate the projected success rates of parathyroidectomy if unilateral neck explorations had been performed based on the results of sestamibi scanning, instead of bilateral explorations.

RESULTS

Sestamibi scanning was correct in 20 (71%) of 28 patients with single adenomas, 4 (44%) of 9 patients with multiple adenomas, and 0 (0%) of 3 patients with hyperplasia. If unilateral neck explorations had been performed on the basis of localization by sestamibi scanning, parathyroidectomy would have failed in 4 (10%) of 40 patients.

CONCLUSIONS

Sestamibi scanning, although helpful, is inadequate for directing unilateral neck exploration for first-time parathyroidectomy. Surgeons who perform unilateral neck exploration based on the results of sestamibi scanning will record a higher failure rate and incur higher costs than those who perform bilateral neck exploration for first-time parathyroidectomy.

[Successful 48-72 h cold storage of dog kidneys with HX-1 solution]

HX-1 solution was used in this study to determine its effects on long term kidney preservation. 20 female and male mongrel dogs were randomly divided into control (HC-WCU solution) and experimental (HX-1 solution) groups. Kidneys were flushed with HC-WCU or HX-1 solution and stored at 0.4 degree C for 48 or 72 h. After being preserved, the kidney was implanted in the right groin of the animal and anastomosed to the iliac vessles. This procedure was immediately followed by a contralateral nephrectomy. The experimental findings were: 1. The maximum serum creatinine levels were 642.60 +/- 158.60 mumol/L and 686.20 +/- 154.04 mumol/L respectively in HC-WCU solution subgroups for 48 or 72 h cold storage. But the maximum serum creatinine levels were 448.32 +/- 36.90 mumol/L and 524.60 +/- 109.38 mumol/L respectively in HX-1 solution subgroups. 2. 80% of the kidneys were viable after 48 h storage in HC-WCU kidney solution, but 100% viable when stored in HX-1 solution: 40% of the kidneys were viable after 72 h storage in HC-WCU solution, but 60% viable when stored in HX-1 solution. 3. Histologically the kidney of dogs that died of renal failure was damaged worse in HC-WCU solution group than that in HX-1 solution group. These results suggest that HX-1 solution is superior to HC-WCU solution for preserving kidneys and HX-1 solution may store up the kidney of dogs to 48-72 h.

Changes in intracellular and extracellular calcium concentration of the myocardial cells during heart failure in children

OBJECTIVE

To explore the relationship between heart failure and changes in intracellular calcium concentration of the myocardium.

METHODS

The intra-and extracellular concentration of ionized calcium and total calcium of myocardium in 11 cases of heart failure was measured using calcium fluorescence indicator Fura-2 and atom absorption spectrophotometry. The activity of the erythrocyte membrane pump was determined with hemolysate chemical method.

RESULTS

The concentration of ionized calcium in myocardial cells and the erythrocyte was significantly higher in the patients with heart failure (280.85 +/- 47.8 nmol/L, 1.76 +/- 0.04 F335/F385) than in those without heart failure (121.88 +/- 13.15 nmol/L, 1.47 +/- 0.08 F335/F385). Total calcium in the erythrocyte was also increased markedly in the patients with heart failure, but the activity of the erythrocyte membrane pump was lower than in those without heart failure. The intracellular calcium of the peripheral erythrocyte and the activity of membrane pump returned to normal after the heart failure was cured.

CONCLUSION

There is excessive calcium accumulation in the myocardium and erythrocyte and the latter may be cause of the disturbance of myocardial diastolic function during heart failure.

Evaluation of the biocompatibility of a nonceramic hydroxyapatite

In this study, the biocompatibility of calcium phosphate cement (CPC) was systematically investigated, which included systemic injection acute toxicity assay, cell culture cytotoxicity assay, gene mutation assay (Ames test), chromosome aberration assay (micronucleus test), DNA damage assay (unscheduled DNA synthesis test) and implant histological evaluation. The results showed that the CPC had no toxicity and all tests for mutagenicity and potential carcinogenicity of CPC extracts are negative. CPC was implanted into the femurs of rabbits under no-load condition and the histology of specimens revealed that the implant tightly joined with the surrounding bone, only a very slight histological inflammatory reaction occurred. Thus, CPC is a highly biocompatible material and seems to be safe for application in humans.

TGF-beta 3 inhibits the increased gene expressions of pulmonary surfactant proteins induced by dexamethasone in fetal rat lung in vitro

OBJECTIVE

To determine the effects of transforming growth factor-beta 3 (TGF-beta 3) on expressions of surfactant proteins (SPs).

METHODS

Northern blot hybridization and reverse transcriptase polymerase chain reaction (RT-PCR) were employed to determine the SP-A, SP-B and SP-C mRNA levels of cultured lung explants and type II cells from fetal rat lungs.

RESULTS

TGF-beta 3 alone did not affect the expressions of SPs either in explants or in type II cells. However, TGF-beta 3 did inhibit the increase of SP-B, SP-C mRNA levels caused by dexamethasone (100 nmol/L), in a dose-dependent manner. Furthermore, TGF-beta 3 had no direct inhibition on the increase of SP-B, SP-C mRNA induced by dexamethasone in type II cells, but had an indirect inhibitory effect mediated by fibroblasts.

CONCLUSION

TGF-beta 3 plays an important inhibitory role in the development of pulmonary surfactant proteins. The present study may provide a possible explanation for the unideal effect of glucocorticoids in the prevention of neonatal respiratory distress syndrome.

Two metabotropic gamma-aminobutyric acid receptors differentially modulate calcium currents in retinal ganglion cells

Metabotropic gamma-aminobutyric acid (GABA) receptors were studied in amphibian retinal ganglion cells using whole cell current and voltage clamp techniques. The aim was to identify the types of receptor present and their mechanisms of action and modulation. Previous results indicated that ganglion cells possess two ionotropic GABA receptors: GABAAR and GABACR. This study demonstrates that they also possess two types of metabotropic GABAB receptor: one sensitive to baclofen and another to cis-aminocrotonic acid (CACA). The effects of these selective agonists were blocked by GDP-beta-S. Baclofen suppressed an omega-conotoxin-GVIA-sensitive barium current, and this action was reversed by prepulse facilitation, indicative of a direct G-protein pathway. The effect of baclofen was also partially occluded by agents that influence the protein kinase A (PKA) pathway. But the effect of PKA activation was unaffected by prepulse facilitation, indicating PKA acted through a parallel pathway. Calmodulin antagonists reduced the action of baclofen, whereas inhibitors of calmodulin phosphatase enhanced it. Antagonists of internal calcium release, such as heparin and ruthenium red; did not affect the baclofen response. Thus, the baclofen-sensitive receptor may respond to influx of calcium. The CACA-sensitive GABA receptor reduced current through dihydropyridine-sensitive channels. Sodium nitroprusside and 8-bromo-cGMP enhanced the action of CACA, indicating that a nitric oxide system can up-regulate this receptor pathway. CACA-sensitive and baclofen-sensitive GABAB receptors reduced spike activity in ganglion cells. Overall, retinal ganglion cells possess four types of GABA receptor, two ionotropic and two metabotropic. Each has a unique electrogenic profile, providing a wide range of neural integration at the final stage of retinal information processing.

[Medicine S inhibits class II MHC expression of intragraft renal in rats]

The Purpose of this study was to address the mechanism of medicine S which has anti-rejection effects of renal allografts in rats. Kidney transplantations were performed from SD to Wistar strain (allogeneic) and from Wistar to Wistar (Isograft) using the same modified technigue described by Fabre and kamada. Experimental rats were divided into five groups. Group I (Isograft group) and group II (allograft group) as controls were not treated with medicine. The others were allograft groups which received medicine S, Cyclosporine A, and low-dose Cyclosporine combined with medicine S, respectively. Renal function and resultant morphology changes were assessed 2, 4 weeks after transplantation. All sections of kidney grafts were stained with monoclonal antibody class II MHC (OX6), and then the surface densities of positive staining were quantified by computer image analysis. The level of molecular expression in group II was significantly increased (7.61 +/- 0.57 vs 0.51 +/- 0.2 of group I, P < 0.01). In groups I and IV, the molecule of expression was reduced, compared with the groups II, III and V (P < 0.05). The results suggest that medicine S decreases the level of class II MHC expression and medicines combined with lowe-dose cyclosporine is more effective than cyclosporine alone.

Mitochondrial tRNA(Leu(UUR)) gene mutation diabetes mellitus in Chinese

OBJECTIVE

To ascertain the prevalence and clinical features of mitochondrial tRNALeu(UUR) gene nucleotide (nt) 3243 A-->G mutation diabetes mellitus in Chinese and to establish the approaches for genetic diagnosis of this subtype of diabetes during routine daily clinical practice.

METHODS

Mitochondrial nt 3243 A-->G mutation was screened among 207 unrelated non-insulin-dependent diabetes mellitus (NIDDM) patients by using polymerase chain reaction (PCR)/Apa I restriction endonuclease digestion. Samples with positive result were confirmed by DNA sequence analysis. Genetic and clinical analysis were carried out in family members of the proband with positive genetic diagnosis.

RESULTS

Positive results were found in two subjects during screening of unrelated NIDDM patients, which account for 2.4%-11.1% of NIDDM subjects with uncommon clinical features (with early age-of-onset, with low body-mass-index and on insulin therapy) or with positive family history of diabetes consistent with or unable to exclude from maternal inheritance. Genetic diagnosis was positive in 10 out of 25 family members in the pedigrees of these two probands.

CONCLUSIONS

Mitochondrial tRNALeu(UUR) gene nt 3242 A-->G mutation should be considered in diabetic patients with the above-mentioned clinical features. The genetic diagnosis in daily clinical practice can be performed with allele specific priming amplification, or PCR/Hae III or Apa I digestion which are technically simple to perform and diagnostically easy to define.

Mechanism of the hardening process for a hydroxyapatite cement

The dynamics for the hydraulic process of calcium phosphate cement (CPC) were investigated by X-ray diffraction quantitative analysis. The results show that the hardening process of CPC is initially controlled by the dissolution of reactants in a 4-h period and subsequently by diffusion through the product layer of hydroxyapatite (HAP) around the grains. The compressive strength rises approximately linearly with the increase of the extent of conversion in a 4-h period, and a maximum compressive strength of about 51 MPa, which is superior to those reported by the references, is obtained in 4 h. Then the compressive strength drops a little with an increase in the extent of conversion. The final product of setting reaction is acicular HAP crystal. Crystal seed not only reduces the setting time but also drops the compressive strength. The variation of pH in CPC slurry from 7.5 to 10.5 reveals that the control step of the dissolution process in the hardening process is the dissolution of dicalcium phosphate anhydrous and the presence of crystal seed will reduce the supersaturation to produce HAP.

Ectopic eye development in Drosophila induced by directed dachshund expression

The dachshund gene encodes a nuclear protein that is required for normal eye development in Drosophila. In the absence of dachshund function, flies develop with severely reduced or no eyes. We show that targeted expression of dachshund is sufficient to direct ectopic retinal development in a variety of tissues, including the adult head, thorax and legs. This result is similar to that observed with the highly conserved Drosophila gene eyeless, which can induce ectopic eye formation on all major appendages. Here, we show that dachshund and eyeless induce the expression of each other and that dachshund is required for ectopic retinal development driven by eyeless misexpression. These results suggest that the control of eye development requires the complex interaction of multiple genes, even at the very highest regulatory levels.

Application of a Shack cube as a beam splitter in interferometers with a local reference beam

A different setup of the Mach-Zehnder interferometer for testing the convergent wave front is described. A Shack cube is used to replace a traditional recollimator and a parallel-plate beam splitter. An equivalent pupil model has been suggested that describes the point diffraction mechanism. The calibration procedures for the Mach-Zehnder interferometer are described. The Shack-cube beam splitter has the advantages of compactness and better reference-beam quality compared with the recollimator and the parallel-plate beam splitter.

[Protective effect of active components extracted from radix Astragali on human erythrocyte membrane damages caused by reactive oxygen species]

A study has been made on the protective activities of active components extracted from Radix Astragali by using reactive oxygen species initiated lipid peroxidation of purified human erythrocyte membrane. The results show that the total flavonoids of Astragalus and total saponins of Astragalus can significantly inhibit the membrane lipid peroxidation generated by O2.-, H2O2 and UV rays, while the total polysaccharide of Astragalus possesses weaker protective activity.

Interaction between prostacyclin and nitric oxide in the reflex control of the coronary circulation in conscious dogs

OBJECTIVE

Our goal was to determine the role of nitric oxide (NO) on the coronary vasodilation induced by prostacyclin (PGI2) in conscious dogs.

METHODS

Dogs were chronically instrumented for the measurements of coronary blood flow (CBF), left ventricular pressure (LVP), mean arterial pressure (MAP) and heart rate (HR).

RESULTS

Intravenous injections of PGI2 caused dose-dependent increases in CBF, and decreases in MAP and late diastolic coronary resistance (LDCR). For instance, CBF increased by 128 +/- 19% (P < 0.05) from 30 +/- 3.5 ml/min and LDCR decreased by 73 +/- 3% (P < 0.05) from 2.57 +/- 0.20 mmHg/ml/min following injection of PGI2 (1.0 microgram/kg). After infusion of nitro-L-arginine (NLA, 35 mg/kg) intravenously, the coronary vasodilation induced by PGI2 was partially attenuated. PGI2 (1.0 microgram/kg) increased CBF by 55 +/- 15% from 33 +/- 5.3 ml/min and decreased LDCR by 42 +/- 9% (both P < 0.05, compared with before NLA) from 3.29 +/- 0.39 mmHg/ml/min. Infusion of L-arginine (100 mg/kg) reversed the action of NLA. For example, PGI2 (1.0 microgram/kg) increased CBF by 115 +/- 15% from 36 +/- 6 ml/min and decreased LDCR by 68 +/- 3% from 3.02 +/- 0.36 mmHg/ml/min (both P > 0.05, compared with before NLA). Atropine (0.1 mg/kg) partially attenuated the coronary vasodilation induced by PGI2 the magnitude of which was almost identical to that by NLA. NLA or atropine also blunted the coronary vasodilation induced by acetylcholine, while the coronary vasodilation induced by nitroglycerin was not affected by NLA.

CONCLUSION

Our results indicate that the coronary vasodilation induced by PGI2 was partially attenuated by NLA or atropine, suggesting that the coronary vasodilation induced by PGI2 is due to two components: a reflex parasympathetic cholinergic vasodilation mediated by NO and a direct action of PGI2.

Three distinct domains in the HOX-11 homeobox oncoprotein are required for optimal transactivation

HOX-11 (tcl-3) is a homeobox oncogene isolated from the breakpoint region of the t(10;14) chromosomal translocation recurring in T-cell acute lymphoblastic leukemia. Here we demonstrate that the HOX-11 homeoprotein mediates transactivation of reporter genes through various promoters in both mammalian and yeast cells. By deletion analysis, the transactivation domains of HOX-11 have been mapped to three amino acid stretches in the homeoprotein, the glycine-proline-rich region at the amino terminus, the homeodomain and the glutamine-rich region at the carboxyl terminus. The three distinct functional domains of HOX-11 act in concert for optimal transactivation. In addition, the homeodomain of HOX-11 appears to be differentially utilized in a promoter-dependent manner. Our data support the notion that the HOX-11 homeoprotein functions as an oncogenic transcription activator in leukemogenesis.

Function and production of nitric oxide in the coronary circulation of the conscious dog during exercise

This study determined the changes in NO production from the coronary circulation of the conscious dog during exercise. The role of endogenous NO as it relates to coronary flow, myocardial work, and metabolism was also studied. Mongrel dogs were chronically instrumented for measurements of coronary blood flow (CBF), ventricular and aortic pressure, and ventricular diameter, with catheters in the aorta and coronary sinus. Acute exercise (5 minutes at 3.6, 5.9, and 9.1 mph) was performed, and hemodynamic measurements and blood samples were taken at each exercise level. Nitro-L-arginine (NLA, 35 mg/kg IV) was given to block NO synthesis, and the exercise was repeated. Blood samples were analyzed for oxygen, plasma nitrate/nitrite (an index of NO), lactate, glucose, and free fatty acid (FFA) levels. Acute exercise caused significant elevations in NO production by the coronary circulation (46 +/- 23, 129 +/- 44, and 63 +/- 32 nmol/min at each speed respectively, P < .05). After NLA, there was no measurable NO production at rest or during exercise. Blockade of NO synthesis resulted in elevations in myocardial oxygen consumption and reductions in myocardial FFA consumption for comparable levels of CBF and cardiac work. The metabolic changes after NLA occurred in the absence of alterations in myocardial lactate or glucose consumptions. NO production by the coronary circulation is increased with exercise and blocked by NLA. The absence of NO in the coronary circulation during exercise does not affect levels of CBF, because it shifts the relationship between cardiac work and myocardial oxygen consumption, suggesting that endogenous NO modulates myocardial metabolism.

Role of endothelium-derived nitric oxide in the modulation of canine myocardial mitochondrial respiration in vitro. Implications for the development of heart failure

The mechanism responsible for the regulation of cardiac function by endogenous nitric oxide (NO) remains unclear. In this investigation, O2 consumption by freshly isolated myocardial muscle segments from the left ventricular free wall of canine hearts was quantified by a Clark-type O2 electrode at 37 degrees C. S-nitroso-N-acetylpenicillamine (SNAP, 9 +/- 3% to 50 +/- 8%), bradykinin (BK, 14 +/- 3% to 30 +/- 5%), or carbachol (CCh, 15 +/- 4% to 29 +/- 4%) significantly attenuated tissue O2 consumption at doses of 10(-7) to 10(-4) mol/L (mean +/- SE, P < .05). The effects of BK and CCh, but not SNAP, were blocked by 10(-4) mol/L NG-nitro-L-arginine, consistent with both BK and CCh stimulating NO biosynthesis and with SNAP decomposing to release NO, respectively. Similar doses of 8-Br-cGMP caused a respiratory inhibition, but to a lesser extent (9 +/- 2% to 14 +/- 6%). A mitochondrial uncoupler, 2,4-dinitrophenol (at 1 mmol/L), blocked the effects of 8-Br-cGMP, but not those of SNAP, BK, or CCh, suggesting that the major site of action of NO is on mitochondrial electron transport. Myocardial muscle from dogs with pacing-induced heart failure had a basal O2 consumption rate of 251 +/- 21 nmol.min-1.g-1, which was 54% higher than the rate seen in muscle from normal healthy canine hearts. The inhibitory effects of BK and CCh on O2 consumption were not observed in failing cardiac tissue, but SNAP showed an unaltered inhibitory effect. Therefore, our results indicate that NO released from microvascular endothelium by BK, stimulation of muscarinic receptors, and perhaps flow velocity may play an important physiological role in the control of cardiac mitochondrial respiration, and the loss of this regulatory function may contribute to the development of heart failure.

Loss of nitric oxide production in the coronary circulation after the development of dilated cardiomyopathy: a specific defect in the neural regulation of coronary blood flow

1. The aims of our study were to determine the role of nitric oxide (NO) in cholinergic reflex dilation of the coronary circulation in normal healthy conscious dogs and after the development of pacing-induced dilated cardiac myopathy and overt congestive heart failure. 2. Dogs were instrumented using sterile surgical techniques under general anaesthesia and allowed to fully recover. The Bezold-Jarisch reflex was stimulated by the intra-atrial injection of veratrine or the intravenous injection of PGI2, while the carotid chemoreflex was stimulated by the intracarotid injection of nicotine. Experiments were performed before and after the development of overt congestive heart failure (HF) caused by rapid left ventricular pacing for 4 weeks. 3. The release of NO, or NO-mediated vascular relaxation following administration of acetylcholine (ACh) may have little physiological significance since as ACh is released from nerve endings in vivo. Stimulation of the Bezold-Jarisch or carotid chemoreflex resulted in typical vagal cholinergic reflex coronary vasodilation, an increase in coronary blood flow and a decrease in coronary vascular resistance, which was substantially reduced following NO synthesis inhibition with nitro-L-arginine. 4. After the development of severe congestive HF, the production of NO by sieved coronary microvessels from the heart was markedly reduced accompanied by a 60-80% reduction in both the mRNA (northern blot) and protein (western blot) for endothelial NO synthase in the aorta. 5. After the development of severe pacing-induced HF, activation of the Bezold-Jarisch or carotid chemoreflex no longer resulted in coronary vasodilation due to the disappearance of NO production from the coronary circulation. 6. Therefore, cholinergic reflex coronary vasodilation is mediated by NO. Because coronary blood vessels lose the ability to produce NO after the development of HF, reflex cholinergic coronary vasodilation is markedly altered, uncovering a previously undiscovered specific defect in the integrated control of the coronary circulation in the failing heart.

Reoperation for persistent or recurrent primary hyperparathyroidism

OBJECTIVE

To analyze the causes and outcomes of reoperation for persistent or recurrent primary hyperparathyroidism.

DATA SOURCES

Medical records of 102 patients with persistent or recurrent primary hyperparathyroidism who underwent reoperation by 1 surgeon between 1985 and 1995.

STUDY SELECTION

Only patients with persistent or recurrent primary hyperparathyroidism were selected; patients with secondary hyperparathyroidism, parathyroid cancer, familial hyperparathyroidism, and previous thyroid operations were omitted.

DATA EXTRACTION

Performed by a single unblinded researcher.

DATA SYNTHESIS

Reasons for failed parathyroid operations included tumor in ectopic position (53%), incomplete resection of multiple abnormal glands (37%), adenoma in normal position missed during previous surgery (7%), and regrowth of previously resected tumor (3%). Of the ectopic glands, 28% were paraesophageal, 26% in the mediastinum (nonthymic), 24% intrathymic, 11% intrathyroidal, 9% in the carotid sheath, and 2% in a high cervical position. Eighty-three percent of ectopic glands were accessible via cervical incision. The success rate of reoperations was 95%. One patient (1%) became permanently hypocalcemic after reoperation; 1 patient (1%) suffered permanent unilateral vocal cord paralysis. The sensitivities of preoperative localization studies were as follows: technetium Tc 99m sestamibi scan, 77%; magnetic resonance imaging, 77%; selective venous catheterization for intact parathyroid hormone, 77%; thallium-technetium scan, 68%; ultrasonography, 57%; and computed tomography, 42%.

CONCLUSIONS

Repeated parathyroidectomy can be avoided in more than 95% of patients if an experienced surgeon performs bilateral cervical exploration during the initial parathyroid operation. For patients with persistent or recurrent primary hyperparathyroidism, preoperative localization studies and a focused surgical approach can result in a 95% success rate with minimum complications.

Modulation by atrial natriuretic factor of receptor-mediated cyclic AMP-dependent responses in canine pulmonary artery during heart failure

1. Pacing-induced congestive heart failure (CHF) in dogs is associated with increased plasma levels of atrial natriuretic factor (ANF) and inhibition of receptor-mediated cyclic AMP-dependent relaxation in isolated pulmonary arteries (PA). Since ANF is known to be negatively coupled to adenylate cyclase, we studied cyclic AMP-mediated relaxation to isoprenaline (Iso) and arachidonic acid (AA) in PA from control dogs (C), dogs with pacing-induced CHF (CHF) and dogs with bilateral atrial appendectomy and CHF (ATR APP+CHF). 2. In CHF, plasma ANF levels increased from a baseline of 80 +/- 8 pg ml-1 to 283 +/- 64 pg ml-1 (P < 0.05), but the ATR APP+CHF group failed to show this increase (67 +/- 7 pg ml-1 vs 94 +/- 15 pg ml-1, P = NS). Plasma ANF levels, however, did not influence myocardial dysfunction in CHF. 3. The relaxation of 49 +/- 5% to 1 microM Iso in C was reduced to 23 +/- 4% in CHF (P < 0.05), but relaxation of 49 +/- 12% was observed in the ATR APP+CHF group (P = NS vs C). Relaxation responses to 10 microM AA were as follows: 77 +/- 5% (C, n = 8), 27 +/- 8% (CHF, n = 10, P < 0.05 vs C), and 93 +/- 5% (ATR APP+CHF, n = 5). The presence of CHF, or the plasma ANF levels, did not affect responses to cyclic GMP-mediated relaxing agents in PA. 4. These data indicate that the myocardial performance in CHF is not influenced by plasma ANF levels. However, altered cyclic AMP-mediated relaxation in PA during CHF is, in part, modulated by circulating ANF levels.