Contribution of the ventricles and the atrial appendages to the elevation of plasma atrial natriuretic factor (ANF) during pacing-induced heart failure in conscious dogs

The goal of our study was to determine whether the elevation in plasma ANF was produced by the atrial appendages or ventricular tissue during pacing-induced heart failure in chronically instrumented conscious dogs (sham) or dogs with bilateral atrial appendectomy. Acute volume expansion caused a significant elevation of plasma ANF from 80 +/- 8 to 149 +/- 26 pg/ml (p < 0.01) in sham dogs, but caused no significant change from 67 +/- 7 to 84 +/- 8 pg/ml in atrial appendectomized dogs. There were increases in left ventricular end-diastolic pressure (LVEDP) and left atrial pressure (LAP) in both groups of dogs. After rapid left ventricular pacing (210-240 beats/min) for 4 weeks to induce heart failure, dogs in both groups had tachycardia, elevated LVEDP and higher LAP. Plasma ANF was increased by 250% to 283 +/- 64 pg/ml (p < 0.01) in sham dogs, and only 40% to 94 +/- 15 pg/ml (p > 0.05) in atrial appendectomized dogs. In response to volume expansion, there were further increases in LVEDP and LAP in both groups of dogs, but plasma ANF was not elevated (288 +/- 39 pg/ml) in sham dogs and only slightly increased (132 +/- 7 pg/ml) in atrial appendectomized dogs. Our results suggest that, during pacing-induced heart failure, the atrial appendages are the major source of elevated plasma ANF, and the remaining atrial and ventricular tissue, even when maximally stretched, can only modestly increase plasma ANF.

A truncated hMSH2 transcript occurs as a common variant in the population: implications for genetic diagnosis

Germline mutations of the hMSH2 gene are responsible for many cases of hereditary nonpolyposis colorectal cancer. While screening for hMSH2 gene mutations in hereditary nonpolyposis colorectal cancer kindreds, we observed that a previously reported germline mutation is in fact a common, alternatively spliced variant in the population. Using RT-PCR and the protein truncation test, the hMSH2 exon 13 deletion variant was found in more than 90% of individuals. The exon 13 deletion transcript was only present in lymphocyte RNA, no abnormalities were detected in genomic DNA flanking exon 13, and the deletion transcript is apparently not translated. These findings highlight further that caution should be exercised in providing genetic risk assessment on the basis of currently used germline mutation detection strategies.

Mitigation of nitrofurantoin-induced toxicity in the perfused rat liver

1. Nitrofurantoin is an antimicrobial agent which produces hepatotoxicity caused by the redox cycling of the nitro group and its radical anion. This futile cycling triggers a complex series of events known collectively as oxidative stress. 2. Our goal was to determine treatment strategies which could mitigate nitrofurantoin-induced toxicity in the isolated perfused rat liver. We co-infused various agents which blocked early or late events in the progression to toxicity. Tissue levels of glutathione and protein thiols were measured as indicators of the progression to toxicity and lactate dehydrogenase leakage into the perfusate was used as a marker of irreversible cell death. 3. Five treatments significantly (P < 0.05) decreased LDH leakage (reported as thousands of units accumulated in perfusate at 300 min, mean+/-standard error, n = 3-4) when compared to nitrofurantoin alone (274 +/- 37). These treatments were adenosine-2'-monophosphate (120 +/- 53), penicillamine (90 +/- 29), N-(2-mercaptopropionyl)-glycine (120 +/- 49) and bromosulfophthalein with (80 +/- 29) or without 5,5'-difluro-1,2-bis(O-aminophenoxy)ethane-N,N,N'N'-tetraace tic acid (101 +/- 46). Two other treatments, N-acetylcysteine (183 +/- 7) and dithiothreitol (166 +/- 59) delayed the onset of toxicity. Finally, calpeptin (319 +/- 34) which blocks activation of nonlysosomal proteases was ineffective. 4. We concluded that early intervention on the pathway to toxicity was most effective. The strategies detailed here may prove beneficial in treating hepatotoxicity seen following nitrofurantoin therapy.

[An experimental study on compound anisodine III for softening scar of mouse skin after burn]

OBJECTIVE

The aim of this study was to investigate the mechanism of compound anisodine (CA) III which can rapidly soften the cicatrized tissue in clinical practice.

METHODS

2 mol/L NaOH was applied onto the back of 36 mice for one minute to induce deep grade skin burn injury. After 1 week local cicatrization occurred. The mice were randomly divided into 3 groups: 1 ml saline was used in group I as control, hyaluronidase 150 U dissolved in 1 ml 2% procaine was used in group II and 0.005% CA 0.1 ml in 2% procaine 1 ml with hyaluronidase 150 U was used in group III. Subcutaneous injection once every other day for two weeks was the method of drug administration in all the 3 groups and then all the rats were euthanized. The burned skin was sectioned for HE and modified Masson's stains.

RESULTS

Histopathology revealed there were epidermis proliferation, keratinization and fibrosis with disorderly arranged collagenous fibers invading into muscles and a large amount of inflammatory cells infiltrating the lesion in groups I and II. However, the skin was nearly normal in group III.

CONCLUSIONS

CA III can inhibit the epidermic and collagenous proliferation, improve the tissue blood supply and have antiinflammatory effect to prevent scar formation and promote epidermic repair in the skin.

Abnormal coronary flow reserve in patients with angina pectoris and hypertensive left ventricular hypertrophy

OBJECTIVE

To assess coronary flow reserve using a computer-assisted method with intracoronary papaverine in patients with angina pectoris.

PATIENTS AND METHODS

Coronary arterial diameter, cross-sectional area and blood flow velocity were measured during coronary arteriography before and after intracoronary papaverine in 26 control subjects, 45 patients with significant coronary artery disease (> 50% luminal narrowing), 16 patients with syndrome X and 14 patients with hypertension and left ventricular hypertrophy (LVH).

RESULTS

After intracoronary administration of papaverine, proximal diameter, cross-sectional area, blood velocity, flow volume and reserve capacity of both left anterior descending and right coronary arteries were lower in patients with significant coronary stenosis than in the controls. Despite similar changes in diameter and cross-sectional area, the blood velocity, flow volume and reserve capacity of the two vessels were also lower in patients with syndrome X than in the controls. In 14 patients with hypertension and LVH, although the blood velocity and flow volume were augmented for the two arteries and did not differ from those in the controls, the flow reserve was reduced because of higher baseline blood velocity and flow volume.

CONCLUSIONS

Coronary flow reserve is reduced in patients with coronary artery disease, syndrome X or hypertensive LVH, which may be related to abnormal changes at different levels of the coronary vasculature or resting flow states.

Shearing interferometer with a Kitty self-pumped phase-conjugate mirror

A shearing interferometer with a Kitty-type self-pumped phase-conjugate mirror is developed. The measurement of the focal length of a lens is demonstrated with a standard deviation of 1.5%. In addition, we measured the microdisplacement in the range of tens of micrometers with an error less than 2% by using the interferometer.

Glottic carcinoma with a fixed true vocal cord: outcomes after neoadjuvant chemotherapy and supracricoid partial laryngectomy with cricohyoidoepiglottopexy

Twenty patients with glottic squamous cell carcinoma and a fixed true vocal cord underwent neoadjuvant chemotherapy followed by supracricoid partial laryngectomy with cricohyoidoepiglottopexy. Phonation, respiration, and deglutition were preserved. Local control was better than has been previously reported for either extended vertical partial laryngectomy or radiation therapy. All patients were monitored for at least 3 years or until death. The Kaplan-Meier 3-year survival, local recurrence, nodal recurrence, distant metastasis, and second primary rates were 75%, 10.8%, 5%, 10.8%, and 10.8%, respectively. Overall local control was achieved in all cases, and laryngeal preservation in 90%. Our experience suggested that neoadjuvant chemotherapy with supracricoid partial laryngectomy with cricohyoidoepiglottopexy deserves further consideration in the treatment of glottic tumors with a fixed true vocal cord.

[The influence of HX- I on rabbit thyroid allografts]

We studied the anti-rejection effect of HX- I, a preparation of traditional Chinese herbs, on rabbit thyroid allografts. The transplantations were performed on 28 rabbits after total thyroidectomies. The grafting sites were in their pretrachial muscles. These animals were divided into four groups, namely, Group I: homografts: Group I: allografts without medication; Group II: allografts with dexamethason (0.25 mg/(kg.d) intramuscularly), and Group IV: allografts with HX-I water solution, (5g/(kg.d), peros). The medication lasted 28 days. Blood samples were drawn every week postoperatively. Serum T3 and T4 were tested by RIA. The grafts were removed for histopathological evaluation on the 28th day postoperatively. The histopathology of rejection and survival were scored and classified. On the 7th and 14th days, serum T3 and T4 levels were almost the same between groups. On the 21st and 28th days, the T3 and T4 levels were higher in Groups I and IV than those in Group II (P < 0.05). The histopathological findings were; in Group I, damaged follicles with much lymphocytes infiltration and fibrosis, and 6 cases being rejected; in Group II, two deaths and three cases with damaged thyroid tissue and much lymphocytes infiltration; in Group IV, three cases with damaged thyroid tissue and four intact grafts. Our results indicate that HX-I and dexamethason both can inhibit rejection in thyroid allografts in rabbits, but dexamethason has more side effects HX-I has many components and the machanism of its early anti-rejection effect is worthy of further study.

Glottic Carcinoma with a Fixed True Vocal Cord: Outcomes after Neoadjuvant Chemotherapy and Supracricoid Partial Laryngectomy with Cricohyoidoepiglottopexy

Twenty patients with glottic squamous cell carcinoma and a fixed true vocal cord underwent neoadjuvant chemotherapy followed by supracricoid partial laryngectomy with cricohyoidoepiglottopexy. Phonation, respiration, and deglutition were preserved. Local control was better than has been previously reported for either extended vertical partial laryngectomy or radiation therapy. All patients were monitored for at least 3 years or until death. The Kaplan-Meier 3-year survival, local recurrence, nodal recurrence, distant metastasis, and second primary rates were 75%, 10.8%, 5%, 10.8%, and 10.8%, respectively. Overall local control was achieved in all cases, and laryngeal preservation in 90%. Our experience suggested that neoadjuvant chemotherapy with supracricoid partial laryngectomy with cricohyoidoepiglottopexy deserves further consideration in the treatment of glottic tumors with a fixed true vocal cord.

The Effects of Doping on the Selectivity and Response Time of Fluoride Ion-Selective Electrodes

We report the effect of doping on the response time and hydroxide ion interference of fluoride ion-selective electrodes made by using membranes consisting of single crystals of CeF3, LaF3 and NdF3, both undoped and doped with divalent cations , and of mixed crystals of neodymium and samarium fluorides (Nd0.95Sm0.05F3 and Nd0.86Sm0.14F3). Doping not only increases the bulk conductivity of the membrane, but also reduces both the response time and the hydroxide ion interference of the electrode. This behaviour is due to an increase in the number of Frenkel defects in the crystal membrane, an effect which increases the mobility of the fluoride ion. It has also been established that doped single crystals of either LaF3 or NdF3 offer the best performance in terms of selectivity.

[Surgery of primary malignant melanomas of the mucosa of the nasal fossa and facial sinuses]

A retrospective analysis of 22 patients with primary malignant melanoma of the nasal fossa and/or paranasal sinuses consecutively managed with surgery at our department from 1975 to 1993 was conducted. Fifteen patients had negative margins of resection. Neoadjuvant chemotherapy and post-operative radiation therapy was associated in 4 and 5 of these 15 patients, respectively. Four patients had positive margins. Adjunctive treatment was chemotherapy and postoperative radiation therapy in 2 and 3 of these 4 patients, respectively. The remaining 3 patients were managed with palliative treatment (debulking surgery and chemotherapy). No patients were lost to follow up. A 3-year follow-up was always achieved. In patients in whom surgical resection achieved negative margins, the 5-year actuarial survival, and local control estimate was 17.9%, and 26.9%, respectively. None of the variables under analysis were statistically related to local recurrence or survival. Death always occurred within 24 months from initial diagnosis in all 7 patients but one in whom surgical resection with negative margins was not achieved or debulking surgery was performed.

An Information Mediator Network for Tasks in Dynamic Environments

Coordination of activities among information workers and services, tracking and managing activities, and intelligent distribution of information are essential to the efficient operation of any large enterprise. This is particularly important in the healthcare domain, where many different organizations must cooperate to provide patient care reliably in a dynamically changing environment. In this review paper we present a distributed system that supports cooperative problem solving, activity management, and intelligent delivery of information in dynamic and unreliable environments. The system consists of a network of task/context managers (TCMs). Each TCM manages a group of related agents. It maintains up-to-date information on availability, operational status, and activities of participating agents, and it acts as a mediator between service requesters and service providers. In addition, the TCM acts as a representative for its agents with other TCMs, allowing different groups of agents to collaborate with one another. This paper describes the system architecture, its implementation and capabilities including matchmaking, plan monitoring, and failure recovery. Our system has been used in prehospital emergency patient information management applications.

Nitric oxide. An important signaling mechanism between vascular endothelium and parenchymal cells in the regulation of oxygen consumption

BACKGROUND

Nitric oxide (NO) is known to be an inhibitor of mitochondrial function. However, the physiological significance of endothelium-derived NO in the control of tissue respiration is not established.

METHODS AND RESULTS

Tissue O2 consumption by skeletal muscle slices of the triceps brachii of normal dogs was measured with a Clark-type O2 electrode/tissue bath system at 37 degrees C. S-Nitroso-N-acetylpenicillamine (SNAP), carbachol (CCh), or bradykinin (BK) decreased tissue O2 consumption by 12 +/- 3% to 55 +/- 8%, 15 +/- 6% to 36 +/- 11%, or 21 +/- 5% to 42 +/- 4% at doses of 10(-7) to 10(-4) mol/L, respectively. The effects of both CCh and BK but not SNAP were eliminated by nitro-L-arginine (NLA, 10(-4) mol/L), consistent with SNAP decomposing to release NO and both CCh and BK stimulating endogenous NO production from L-arginine. Oxygen consumption was also decreased by 8-bromo-cGMP. The mitochondrial uncoupler dinitrophenol blocked the effects of 8-bromo-cGMP but only slightly altered those of SNAP, indicating that the major site of action of NO is the mitochondria. In normal, chronically instrumented, resting conscious dogs, blockade of NO synthase by NLA increased mean arterial pressure by 28 +/- 2.5 mm Hg and hind limb vascular resistance by 114 +/- 12% and decreased blood flow by 39 +/- 3%. Most important, NLA also increased O2 uptake by 55 +/- 9% in hind limb skeletal muscle (P < .05), associated with decreases in PO2 and O2 saturation and an increase in reduced hemoglobin in hind limb venous blood.

CONCLUSIONS

Our results indicate that NO release from vascular endothelial cells appears to play an important physiological role in the regulation of tissue mitochondrial respiration in skeletal muscle and perhaps other organ systems.

Persistent or recurrent hyperparathyroidism in patients with double adenomas

BACKGROUND

Are double parathyroid adenomas a discrete clinical entity or are all hyperplastic parathyroid glands of varying size? This investigation was done to determine whether patients with persistent or recurrent hyperparathyroidism and double adenomas (DA) differ in clinical profile or in response to treatment from patients with hyperplasia.

METHODS

From 1982 to 1993, 37 unselected patients with persistent (11) or recurrent hyperparathyroidism (26) were treated. Twenty-one had DA and 16 had hyperplasia. DAs were defined as two abnormal and two normal parathyroid glands.

RESULTS

Patients with persistent or recurrent hyperparathyroidism caused by DA were older and had more muscle weakness, neuropsychiatric disorders, constipation, and weight loss (p < 0.001) than patients with persistent or recurrent hyperparathyroidism caused by hyperplasia. Nephrolithiasis was more common in patients with recurrent hyperparathyroidism caused by hyperplasia than in patients with recurrent hyperparathyroidism caused by DA (p < 0.001). Serum Ca2+ levels before operation were similar in these groups with variable parathyroid hormone levels. No recurrences occurred in either group (DA [mean, 6 yr]; hyperplasia [mean, 5 yr]). Postoperative levels of serum Ca2+ and parathyroid hormone were normal in both groups.

CONCLUSIONS

Patients with persistent or recurrent hyperparathyroidism caused by DA are older, have different clinical manifestations, and are cured by resection of the second adenoma. These findings support the concept that DA and hyperplasia are distinct entities.

Abnormal left ventricular systolic and diastolic functional response to isometric exercise in idiopathic dilated cardiomyopathy: beneficial effect of captopril

In 19 patients with idiopathic dilated cardiomyopathy and symptoms of congestive heart failure, left ventricular (LV) systolic performance and diastolic velocity profiles were assessed by two- dimensional echocardiography and pulsed wave Doppler at rest and during handgrip exercise before and ninety minutes after administration of captopril (mean dose 25 +/- 12mg; range 12.5-50mg). Although heart rate and blood pressure increased similarly during handgrip exercise before and after captopril treatment, both were lower with handgrip exercise during captopril treatment. The results from this study indicated that acute angiotension converting enzyme inhibition with captopril reduces preload and afterload and ameliorates handgrip exercise-induced LV systolic and diastolic filling dysfunction in patients with congestive heart failure secondary to idiopathic dilated cardiomyopathy.

Clinical significance of complete left bundle branch block in dilated cardiomyopathy

Clinical, electrocardiographic and echocardiographic findings in 64 patients with dilated cardiomyopathy were restrospectively studied. Compared with 51 patients without complete left bundle branch block (CLBBB), 13 patients with CLBBB had higher New York Heart Association (NYHA) functional class (P < 0.05), increased left ventricular end-diastolic and end-systolic diameters (P < 0.002) and myocardial mass (P < 0.02), severe mitral regurgitation (P < 0.01) and higher mortality rate (P < 0.04). Multivariate stepwise regression analysis revealed that the presence of CLBBB was an independent prognostic factor for patients with dilated cardiomyopathy.

[Multidimensional transesophageal echocardiography in the determination of the orificial surface of aortic stenoses in adults. Apropos of 85 cases]

The objective of this study was to assess the validity of multidimensional transoesophageal echocardiography (TOE) in the determination of the orificial surface area of aortic stenosis (AS) in 85 patients, using as a reference the surface area calculated on transthoracic ultrasonography (TTU) by applying the continuity principle (n = 75) and/or by haemodynamic studies using Gorlin's formula (n = 40). Planimetry was able to be performed in 78 of the 85 patients (92%). Planimetry was impossible in 7 patients with massive calcification of the aortic orifice (n = 5) or posterior valve (n = 2). The mean value of the selected angle was 45 +/- 13 degrees (0 to 78 degrees). An excellent correlation was observed between aortic surface area (ASA) measured by multidimensional TOE and TTU (r = 0.94; y = 0.90x +/- 0.10; SEE = 0.10 cm2; p < 0.001). Similarly, the ASA on multidimensional TOE was also well correlated with the haemodynamic surface area (r = 0.90, y = 0.94x +/- 0.05; SEE = 0.09 cm2; p < 0.001). The correlations between multidimensional TOE and TTU measurements (n = 26; r = 0.96; y = 0.85 x +/- 0.11; SEE = 0.07 cm2; p < 0.001) and cardiac catheterization (n = 13; r = 0.92; y = 0.77 x +/- 0.7; SEE = 0.09 cm2; p < 0.001) remained satisfactory in patients with associated aortic incompetence. Multidimensional TOE identifies cases of AS with an ASA on TOE or haemodynamic studies less than or equal to 0.75 cm2 with sensitivities of 93% and 92%, respectively, and a specificity of 100%. Overall, multidimensional TOE allows a precise and reliable evaluation of ASA in the great majority of cases of AS.

Nitric oxide production and NO synthase gene expression contribute to vascular regulation during exercise

Nitric oxide (NO) is a vasodilator produced under normal physiologic conditions primarily by the vascular endothelium lining all blood vessels. The primary stimulus for the production of nitric oxide by the constitutive endothelial nitric oxide synthase (ECNOS, Type II) found in blood vessels is most likely the shear stress, the frictional force, caused by blood flowing through blood vessels. During exercise there is an increase in cardiac output and redistribution of blood flow to increase blood flow in skeletal muscle and in the coronary circulation. These adjustments provide increased oxygen delivery to support aerobic energy production and to sustain the exercise response. NO may be involved in the regulation of vascular tone in exercising skeletal and cardiac muscle by promoting, enhancing the metabolic vasodilation. In addition, the production of NO by capillary endothelium may regulate oxygen consumption by mitochondria through chemical interactions between NO and the iron-sulfur center of these enzymes. Finally, brief exercise training may alter the gene expression for the enzyme, the constitutive endothelial NO synthase, which forms NO and may be part of the vascular adaptation seen after aerobic exercise training. Furthermore, if there is a genetic predisposition to produce NO, as in world class athletes or animals bred to race, NO may contribute to spectacular exercise performance. These three potential roles of NO will be discussed and data presented to support each of these in our review.

Vaccination of sheep against Schistosoma japonicum with either glutathione S-transferase, keyhole limpet haemocyanin or the freeze/thaw schistosomula/BCG vaccine

The protective potential of glutathione S-transferase (GST), keyhole limpet haemocyanin (KLH) and the freeze/thaw (F/T) schistosomula/BCG vaccine was evaluated against Schistosoma japonicum in the natural sheep host. Groups of ten sheep each were vaccinated as follows: Group I: 2 x F/T 30,000 schistosomula+BCG 3 x 10(8) organisms, with a 2 week interval between vaccinations (F/T 'Low'). Group II: 3 x F/T 20,000 schistosomula+BCG 3 x 10(8), with 4 week interval (F/T 'High'). Group III: 2 x GST 0.24 mg+FCA (Freund's complete adjuvant) with 2 week interval (GST 'Low'). Group IV: 3 x GST 0.24 mg+FCA, with 4 week interval (GST 'High'). Group V: 2 x KLH 1.0 mg in phosphate-buffered saline (PBS), with 2 week interval (KLH 'Low'). Group VI: 3 x KLH 1.0 mg in PBS, with 4 week interval (KLH 'High'). Group VII: control (not vaccinated). Specific antibody, detected by GST-enzyme-linked immunosorbent assay (ELISA) and KLH-ELISA on the day after the last vaccination and 1, 2 and 3 weeks post-challenge, was found in all GST- or KLH-vaccinated groups. The same was found in F/T schistosomula-vaccinated groups against crude adult worm antigen (AWA). In Western blotting all GST-vaccinated sera recognized 26 kDa and 28 kDa bands on the challenge day and at 3 and 11 weeks post-challenge. Mean faecal egg counts between Weeks 6 and 10 post-challenge were reduced in a statistically significant way at five time points in the four groups, i.e. 83.38% (P < 0.005) in Group II, 49.29% (P < 0.025) in Group III, 47.9% (P < 0.05) and 71.15% (P < 0.01) in Group IV, 52.0% (P < 0.025) and 66.38% (P < 0.025) in Group VI. On autopsy and perfusion 1 week after the last faecal count, adult worm reductions were obtained of 40.36% (P < 0.05) in Group I, 37.26% (P < 0.025) in Group II, 24.73% (not significant) in Group III, 35.93% (P < 0.025) in Group IV, 27.46% (P < 0.05) in Group V and 33.81% (P < 0.01) in Group VI. Mean tissue egg densities were also reduced significantly in Groups III, IV and VI, especially in Group IV vaccinated animals. Mean liver egg granuloma diameters of the vaccinated groups were found to be less than those of the controls but there was no statistical significance.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacodynamics of plasma nitrate/nitrite as an indication of nitric oxide formation in conscious dogs

BACKGROUND

The present investigation was undertaken to better understand the production of nitric oxide (NO) in vivo as measured by alterations in plasma nitrite or nitrate in blood samples from studies in experimental animals or clinical studies in humans.

METHODS AND RESULTS

Plasma samples were taken from the aorta, the coronary sinus, a peripheral vein in the leg (skeletal muscle), or the right ventricle (mixed venous) in chronically instrumented conscious dogs. Plasma nitrite was converted to NO gas in an argon environment by use of hydrochloric acid, and plasma nitrate was converted first to nitrite with nitrate reductase and then to NO gas with acid. Standard curves were constructed, and the amount of nitrite and nitrate in plasma was determined. The primary metabolite was nitrate, whereas nitrate was approximately 10% of the total and remained constant. In the resting dog, the only vascular bed with a positive arterial-venous nitrate difference, evidence for production of NO, was the heart. Nitrate infusion into quietly resting dogs resulted in increases in plasma nitrate up to 38 +/- 3.4 mmol/L, increases in systemic arterial pressure, and a marked diuresis. The plasma half-life was calculated as 3.8 hours. The volume of distribution was calculated as 0.215 L/kg, or equivalent to the extracellular volume.

CONCLUSIONS

These studies indicate that nitrate is a reliable measure of NO metabolism in vivo but that because of the long half-life, nitrate will accumulate in plasma once it is produced. Because of the large volume of distribution (21% of body weight versus the 4% of body weight usually attributed to plasma volume, the compartment in which nitrate is measured), simple measures of plasma nitrate underestimate by a factor of 4 to 6 the actual production of nitrate or NO by the body. In disease states, such as heart failure, in which renal function and extracellular volume are altered, caution should be exercised when increases in nitrate in plasma as an index of NO formation are evaluated.

Sequential expression and differential localization of I-, L-, and T-fimbrin during differentiation of the mouse intestine and yolk sac

During the differentiation of the intestine epithelium, three cytoskeletal proteins, villin, fimbrin, and myosin I, are sequentially expressed and localized to the apical membrane. Recently, we found that in the adult mouse and human, three fimbrin isoforms are expressed in a cell specific manner. I-fimbrin is expressed by intestine and kidney epithelial cells, L-fimbrin is expressed by leukocytes and many tumors, while T-fimbrin is expressed by various cells and tissues. Because non-intestinal isoforms of fimbrin could be expressed early in development, the expression of fimbrin isoforms during days 10.5 to 16.5 of intestine development was investigated. By immunofluorescence microscopy, T-fimbrin was detected in the early stages of intestinal epithelial cell differentiation until day 14.5 and was localized predominantly at the apical surface. L-fimbrin was also detected during this period but it was localized to the basal surface of the epithelium instead of the apical surface. By day 16.5 no L or T-fimbrin was detected in the epithelium. I-fimbrin was first detected at day 14.5 and a brush border-like apical localization pattern was seen by day 16.5. Unlike the intestinal cells, the visceral endoderm expressed I, L, and T-fimbrin throughout the period examined, with the level of I-fimbrin increasing as time progresses. L-fimbrin was more evident at the earlier stage than at the later stage of the development. Collectively, these results suggest that three fimbrin isoforms play different roles during epithelial cell differentiation. T- and I-fimbrin expression could be critical for the formation and extension of the microvilli whereas L-fimbrin may play a role in controlling cell adhesion.

[The effective time of HX solution for rat liver preservation]

The effects of HX solution and UW solution for rat liver preservation were studied with non-circulated isolated perfused rat liver model. Sixty-six inbred Wistar rat livers were randomly preserved for 12, 18, 24, and 30h with HX solution or UW solution. The effects were assessed by measuring hepatic tissue water content, sinusoidal lining cell mortality, Krebs-Henseleit's perfusate aspartate aminotransferase, the number of livers secreting bile during isolated perfusion, and by observing the morphological changes in liver. The experimental results suggest that the effects of HX solution for rat liver preservation be similar to those of UW solution within 24h storage.

Selective impairment of vagally mediated, nitric oxide-dependent coronary vasodilation in conscious dogs after pacing-induced heart failure

BACKGROUND

Activation in conscious dogs of the carotid chemoreflex or cardiac receptors results in coronary vasodilation that is mediated by a vagal cholinergic mechanism. Our previous study showed that the coronary vasodilation following activation of carotid chemoreflex is also mediated by nitric oxide (NO). In addition, NO production is depressed after the development of heart failure. Therefore, we hypothesized that the coronary vasodilation after activation of reflexes that elicit efferent vagal coronary vasodilation would be blunted in conscious dogs after pacing-induced heart failure due to the disappearance of NO.

METHODS AND RESULTS

Mongrel dogs were chronically instrumented using sterile techniques for measurements of systemic hemodynamics and left circumflex coronary blood flow (CBF). Without the heart rate controlled, intra-atrial injection of veratrine (4 micrograms/kg) caused bradycardia (-36 +/- 3 beats per minute). With the heart rate controlled, veratrine increased CBF in a dose-dependent manner: for example, 4 micrograms/kg of veratrine increased CBF by 54 +/- 5% from 38 +/- 4.9 mL/min (P < .05). The increases in CBF induced by veratrine were markedly blunted by nitro-L-arginine (NLA). Activation of carotid chemoreflex by nicotine increased CBF by 121 +/- 9% from 32 +/- 4 mL++/min (P < .05) with the heart rate controlled and caused bradycardia (-32 +/- 5 beats per minute) without the heart rate controlled. After the development of heart failure, in response to activation of carotid chemoreflex or cardiac receptors the coronary vasodilation was almost abolished (CBF increased by only 23 +/- 8% or 11 +/- 3%, P < .05 compared with control). There still was a marked bradycardia after injections of nicotine or veratrine (-50 +/- 11 or -48 +/- 7 beats per minute).

CONCLUSIONS

Our results indicate that vagally mediated coronary vasodilation is selectively attenuated in conscious dogs after pacing-induced heart failure, whereas the vagally mediated bradycardia is preserved. Since muscarinic receptor-induced coronary vasodilation is mediated by NO, the disappearance of NO from blood vessels leads to a defect in the integrated neural regulation of coronary blood flow and myocardial function during heart failure.

[Protective effect of total flavonoids of radix Astragali on mammalian cell damage caused by hydroxyl radical]

The protective effect of total flavonoids of Radix Astragali (TFA) on V79 cell damage caused by H2O2-Fe2+ system has been studied. The results show that total flavonoids of Radix Astragali inhibit lipid peroxides and increase SOD activity. It has also been found that TFA has different protective effect against various damages of V79 cells caused by hydroxyl radical.

[Effects of Sichuan herba Epimedii on the concentration of plasma middle molecular substances and sulfhydryl group of "yang-deficiency" model animal]

The effects of tonifying the kidney and strengthening the "Yang" produced by the extracts of Chinese herbs Epimedium wushanense and E. pubescens were studied in this paper. The results showed that both two herbs could decrease the concentration of plasma middle molecular substances and increase the concentration of plasma sulfhydryl group of "Yang-deficiency" model mice, thus suggesting that the above-said tonifying and strengthening effects of Herba Epimedii may result from its effects on middle molecular substances and sulfhydryl group, so as to strengthen the body resistance and eliminate the invading pathogenic factors.

Expression of binding of plasminogen, thrombospondin, vitronectin, and fibrinogen, and adhesive properties by Escherichia coli strains isolated from patients with colonic diseases

Escherichia coli strains isolated from patients with colonic disorders (n = 27) and strains isolated from the rectal mucosa of healthy subjects (n = 24) were compared with respect to expression of cell surface hydrophobicity, carriage of intestinal virulence factors, adhesion to tissue culture cells, and expression of binding of extracellular matrix proteins and plasma proteins. Strains isolated from patients with colonic disease did not express a more hydrophobic cell surface than strains from healthy subjects. Few strains from both groups carried genes encoding for recognised virulence factors of E coli. Only one strain, carrying the eae gene induced actin polymerisation in tissue culture cells. Strains from patients with colonic diseases adhered to HT29 cells, which are of intestinal origin, to a higher extent than E coli from healthy subjects. Significantly more strains from patients with colonic disorders than E coli from healthy subjects expressed binding of fibronectin, collagens, laminin, vitronectin, plasminogen, throbospondin, and fibrinogen. Expression of binding of these proteins may influence the pathogenesis of colonic disease by mediating binding to ulcerated tissue, preventing complement induced lysis of bacteria and by exerting proteolytic activity. There was no correlation between serotype, expression of cell surface hydrophobicity, and binding of extracellular matrix and plasma proteins.

[The protective effects of drugs H and X on liver cold ischemic injury]

Using isolated perfusion rat liver model (IPRL), we studied the protective effects of drugs H and X on rat's liver cold ischemic injury. After the rat's liver was preserved for 12 hours in Collins II solution with the addition of drugs H and X, the necrotic rate of sinusoidal lining cells was significantly lower than that of control group. Within certain range of the dosage of drugs H and X, the necrotic rate of sinusoidal lining cells was in the inverse ratio of the dosage in the Collins II solution. We also found that drugs H and X had obvious protective effect on liver cell redox function. But these drugs could not inhibit tissue from swelling after Collins II solution preservation. The protective mechanisms of the drugs maybe relate to the remoral of free radicals and suppression of Kupffer's cells activity.

Primary hyperparathyroidism in patients who have received radiation therapy and in patients who have not received radiation therapy

BACKGROUND

Primary hyperparathyroidism (HPT) occurs more frequently in persons who have been exposed to low-dose therapeutic radiation. Little information is available concerning whether or not the clinical, metabolic, and pathologic manifestations, as well as outcome, differ in these patients when compared with patients with sporadic HPT.

STUDY DESIGN

Records from 438 unselected patients with primary HPT, who were treated from 1982 to 1993 were retrospectively analyzed. All patients prospectively received a standard questionnaire preoperatively and postoperatively concerning clinical manifestations and a history of radiation exposure. Forty-nine patients had a history of radiation exposure (rHPT), whereas 389 did not have sporadic HPT (sHPT).

RESULTS

There was no difference in gender (36 women and 13 men versus 289 women and 100 men) or age (mean of 52 +/- 12 versus 57 +/- 16 years) in patients with rHPT or sHPT. Fatigue, neuropsychiatric disorders, memory loss, nocturia, and polyurea were more common in patients with sHPT (p < 0.05), whereas pain in joints was more common in patients with rHPT (63 versus 52 percent; p < 0.001). Serum calcium levels were similar (11.1 +/- 0.8 versus 11.2 +/- 0.8 mg per dL), but serum parathyroid hormone levels were higher in rHPT (448 +/- 14 percent of upper limit of normal versus 371 +/- 12 percent upper limit of normal). The parathyroid pathology was similar in the two groups (single adenoma 74 versus 72 percent, hyperplasia 14 versus 16 percent, and double adenoma 12 versus 12 percent in rHPT versus sHPT, respectively). Thyroid pathology was more common in the rHPT group (multinodular goiter 27 versus 7 percent and papillary thyroid carcinoma 14 versus 0.3 percent). Seven (1.8 percent) of patients not receiving radiation therapy treated by us had persistent HPT, but no patients receiving or not receiving radiation therapy had recurrent HPT during the follow-up period (six years).

CONCLUSIONS

Patients who have HPT after radiation treatment have more thyroid neoplasms but are otherwise quite similar to other patients with primary hyperparathyroidism.

Isoform-specific complementation of the yeast sac6 null mutation by human fimbrin

The actin cytoskeleton is a fundamental component of eukaryotic cells, with both structural and motile roles. Actin and many of the actin-binding proteins found in different cell types are highly conserved, showing considerable similarity in both primary structure and biochemical properties. To make detailed comparisons between homologous proteins, it is necessary to know whether the various proteins are functionally, as well as structurally, conserved. Fimbrin is an example of a cytoskeletal component that, as shown by sequence determinations and biochemical characterizations, is conserved between organisms as diverse as Saccharomyces cerevisiae and humans. In this study, we examined whether the human homolog can substitute for the yeast protein in vivo. We report here that two isoforms of human fimbrin, also referred to as T- and L-plastin, can both substitute in vivo for yeast fimbrin, also known as Sac6p, whereas a third isoform, I-fimbrin (or I-plastin), cannot. We demonstrate that the human T- and L-fimbrins, in addition to complementing the temperature-sensitive growth defect of the sac6 null mutant, restore both normal cytoskeletal organization and cell shape to the mutant cells. In addition, we show that human T- and L-fimbrins can complement a sporulation defect caused by the sac6 null mutation. These findings indicate that there is a high degree of functional conservation in the cytoskeleton, even between organisms as diverse as S. cerevisiae and humans.

National food contamination monitoring programmes-levels of mercury, lead and cadmium in Chinese foods

Six hundred and thirty-four food samples of six kinds were collected from Beijing, Shanghai, Jiangsu, Sichuan, Jilin and Guangdong areas, China and Hg, Pb, Cd contents were determined. The results showed that their levels in the Chinese foods were low; their levels in meat, egg, milk and fish were generally below the national hygienic standard. The average daily dietary intake of Hg, Pb, Cd were 7.25 micrograms, 103.77 micrograms and 30.72 micrograms respectively and they were all less than the ADI established by WHO.

Role of nitric oxide in the regulation of oxygen consumption in conscious dogs

The role of nitric oxide (NO) in the regulation of O2 consumption was studied in chronically instrumented conscious dogs. A specific NO synthesis inhibitor, nitro-L-arginine (NLA, 30 mg/kg i.v.), significantly increased mean arterial pressure from 100 +/- 4 to 134 +/- 5 mm Hg (mean +/- SEM) and total peripheral resistance by 157 +/- 16% and reduced cardiac output by 47 +/- 3% and heart rate by 34 +/- 6% after 120 minutes. Changes in arterial blood gases were not observed. There were significant changes in PO2 (-14 +/- 2 mm Hg), O2 saturation (-21 +/- 2%), the percentage of hemoglobin as oxyhemoglobin (-21 +/- 2%), and O2 content (-3.0 +/- 0.9 vol%) and a significant increase in percent reduced hemoglobin (21 +/- 1%) in mixed venous blood, associated with an increase in O2 extraction (5.1 +/- 0.2 vol%) (all P < .01). O2 consumption was increased from 124 +/- 6 to 155 +/- 9 mL/min (P < .05). Methoxamine, titrated to have hemodynamic effects similar to those of NLA (eg, mean arterial pressure increased from 97 +/- 4 to 131 +/- 5 mm Hg), had much smaller effects on venous blood gases, hemoglobin, and O2 extraction (2.3 +/- 0.7 vol%) and no significant effect on O2 consumption. NLA also caused an increase in O2 consumption of 37 +/- 8% (P < .01) in quietly resting conscious dogs that had undergone pretreatment with hexamethonium and atropine, but no significant change in O2 consumption in dogs anesthetized with barbiturate.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of EDRF/NO in parasympathetic coronary vasodilation following carotid chemoreflex activation in conscious dogs

The role of endothelium-derived relaxing factor (EDRF) in parasympathetic coronary vasodilation following carotid chemoreflex activation induced by nicotine in conscious dogs and stimulation of the vagus nerve in anesthetized dogs was studied. Injection of nicotine (11 +/- 4 micrograms) into the carotid artery increased coronary blood flow (CBF) by 126 +/- 16% from 28 +/- 3 ml/min and reduced late diastolic coronary resistance (LDCR) by 43 +/- 4% from 3.58 +/- 0.52 mmHg.ml-1.min, accompanied by a significant increase in mean arterial pressure and a decrease in heart rate (all P < 0.01). Pacing and propranolol did not change the coronary vascular response to chemoreflex activation. There were still increases in CBF by 113 +/- 17% from 29 +/- 3 ml/min and decreases in LDCR by 41 +/- 5% from 3.13 +/- 0.52 mmHg.ml-1.min (all P < 0.01). After infusion of N omega-nitro-L-arginine (L-NNA) (30 mg/kg), the increase in CBF following chemoreflex activation was only 23 +/- 3% from 37 +/- 3 ml/min, and the fall in LDCR was 19 +/- 3% from 3.09 +/- 0.51 mmHg.ml-1.min. Stimulation of the vagus nerve showed a relationship between stimulation frequency and coronary vasodilation that was significantly inhibited by L-NNA. Thus EDRF plays an important role in mediating parasympathetic coronary vasodilation during chemoreflex activation and perhaps during many reflexes that cause vagal cholinergic vasodilation in the heart.

Role of EDRF in the regulation of regional blood flow and vascular resistance at rest and during exercise in conscious dogs

The contribution of endothelium-derived relaxing factor (EDRF) to the regulation of regional vascular resistance and tissue blood flow at rest and during acute moderate exercise was studied in chronically instrumented conscious dogs. Radioactive microspheres were injected before and during exercise to measure regional blood flow. An infusion of nitro-L-arginine (L-NA), an analogue of L-arginine, was used to inhibit the synthesis of EDRF and resulted in a significant increase in mean arterial pressure, associated with significantly elevated vascular resistance in heart, skeletal muscle, renal and splanchnic circulations and with decreases in tissue blood flow in those regions at rest. Acute exercise caused a typical redistribution of blood flow, in which there was vasodilation in heart and working skeletal muscles, accompanied by vasoconstriction in kidney and splanchnic circulations. L-NA resulted in significantly elevated vascular resistance during vasodilation in heart and working skeletal muscles and also significantly increased vasoconstriction in renal cortex, stomach, pancreas, liver, and colon during exercise. Blood flows during exercise were largely unaffected by L-NA treatment. Our results suggest that whereas EDRF functions to regulate basal vascular tone and vascular resistance during exercise, EDRF has a minor role in determining the pattern of the redistribution of tissue blood flow during exercise.

[Comparative study of organ storage solutions for rat liver preservation: effects of HX and Collins I solution on sinusoidal lining cells and hepatic functions]

The liver sinusoidal lining cell injury and biochemical function changes were studied with isolated perfusion after rat livers had been preserved in HX solution or in Collins II solution. Seventy inbred Wistar rats were randomly divided into control group (n = 10), group H (preserved with HX solution, n = 30), and group C (preserved with Collins II solution, n = 30). The effects of the storage solutions were assessed by measuring the sinusoidal lining cell mortality (SLCM), Krebs-Henseleit perfusate ketone body ratio (PKBR), the hepatic sugar release (SL), and the number of livers secreting bile during isolated perfusion. The results suggest that the HX solution be much superior to Collins II solution in preventing sinusoidal lining cell injury and maintaining normal hepatic functions.

Purification of collagen-binding proteins of Lactobacillus reuteri NCIB 11951

Collagen type-I-binding proteins of Lactobacillus reuteri NCIB 11951 were purified. The cell surface proteins were affinity purified on collagen Sepharose and eluted with an NaCl gradient. Two protein bands were eluted from the column (29 kDa and 31 kDa), and both bound radio-labeled collagen type I. Rabbit antisera raised against the 29 kDa and 31 kDa protein reacted with the affinity-purified proteins in a Western blot with whole-cell extract used as antigen. The N-terminal sequence of the 29-kDa and 31-kDa proteins demonstrated the closest homologies with internal sequences from an Escherichia coli trigger factor protein (TIG.ECOLI). Out of nine other lactobacilli, the antisera reacted only with the L. reuteri and not with the other species tested.

Identification of I-plastin, a human fimbrin isoform expressed in intestine and kidney

The complete cDNA sequence of human intestine-specific plastin (I-plastin) was determined from a clone derived by PCR. It consists of a 97-bp 5' untranslated region, a 1,887-bp coding region, and a 1,655-bp 3' untranslated region. The coding region predicts a 629-residue polypeptide whose sequence displays 86, 75, and 73% identities with chicken intestine fimbrin, human T-plastin, and human L-plastin, respectively. Recombinant I-plastin cross-linked actin filaments into bundles in the absence but not in the presence of calcium. The I-plastin gene was mapped by PCR to human chromosome 3; the L- and T-plastin genes were previously mapped to chromosomes 13 and X, respectively. I-plastin mRNA was detected in the small intestine, colon, and kidneys; relatively lower levels of expression were detected in the lungs and stomach. In contrast, L-plastin expression was restricted to the spleen and other lymph node-containing organs, while T-plastin was expressed in a variety of organs, including muscle, brain, uterus, and esophagus. In contrast to the situation for the intestine, high levels of L- and T-plastin mRNAs were detected in Caco-2, a human colon-derived cell line. Immunofluorescence microscopy detected I-plastin in the brush border of the small intestine and colon. These results identify I-plastin as the human homolog of chicken intestine fimbrin and as a third plastin isoform in humans.

Effects of prolonged darkness on light responsiveness and spectral sensitivity of cone horizontal cells in carp retina in vivo

Light responses of cone- and rod-driven horizontal cells were recorded intracellularly from opened eyes of intact, immobilized carp and the effects of prolonged darkness on these cells were examined. When the retina was left in the dark, responses of cone horizontal cells to a moderate test flash presented once every 10 min gradually and steadily decreased in size (dark suppression effect). Following a repetitive presentation of the test flash, the light responsiveness of the cells was enhanced. In contrast, the rod horizontal cells did not show the dark suppression effect and the light responsiveness of these cells increased in the dark. Effects of prolonged darkness on the spectral sensitivity of L-type and R/G-type cone horizontal cells were also studied. The spectral sensitivity of L-type cells, determined just after background illumination was extinguished, agreed reasonably well with that of red-sensitive (R-) cones, but it matched better that of green-sensitive (G-) cones when determined in prolonged darkness. We further show that depolarizing responses of R/G-type cone horizontal cells to long-wavelength flashes, driven by R-cones, were abolished after prolonged darkness. Taken together, these results suggest that input from R-cones converging onto the cone horizontal cells is more significantly suppressed after prolonged dark adaptation than input from G-cones. Due to the suppression of the R-cone input, enhancement of responses of the L-type cone horizontal cells to long-wavelength stimulation in the presence of a green background light was no longer seen after prolonged darkness.(ABSTRACT TRUNCATED AT 250 WORDS)

Polymorphous ventricular tachycardia after intracoronary papaverine: a report of 3 cases

Three cases with polymorphous ventricular tachycardia following a standard dose of intracoronary papaverine during 102 measurements of coronary flow reserve are reported. This study suggests that all patients should be closely monitored while receiving intracoronary papaverine and that extreme caution should be employed when the drug is administered to patients with QT interval prolongation and poor coronary flow reserve.

Atrial fibrillation and coronary artery disease

A retrospective study of the incidence of atrial fibrillation in 703 consecutive patients who had undergone selective coronary arteriography and left ventricular catheterization between November 1986 and May 1992 was undertaken. The study group included 136 patients with significant coronary stenosis (> 50% diameter reduction) without previous myocardial infarction (group I), 157 with a history of myocardial infarction (group II), 326 with chest pain and normal coronary angiography (group III), 72 with valvular disease (group IV), and 12 with cardiomyopathy (group V). Clinical and electrocardiographic evidence of atrial fibrillation was documented in 75 patients (10.7%), including 2 (1.5%) in group I, 6 (3.8%) in group II, 36 (11%) in group III, 27 (37.5%) in group IV, and 4 (33.3%) in group V. The rate of occurrence of atrial fibrillation was lower in groups I and II than in groups III, IV and V. Atrial fibrillation was rarely found in coronary artery disease.

Double parathyroid adenomas. Clinical and biochemical characteristics before and after parathyroidectomy

OBJECTIVE

There is considerable debate about whether double parathyroid adenomas are a discrete entity or represent hyperplasia with parathyroid glands of varying sizes. This distinction is important because it impacts on the extent of parathyroid resection and the success of the parathyroid operation.

SUMMARY BACKGROUND DATA

Double parathyroid adenomas have been reported to occur in 1.7% to 9% of patients with primary hyperparathyroidism (HPT). It is important for surgeons to differentiate between double adenoma and hyperplasia with glands of varying sizes using gross examination during the initial procedure because microscopic findings of a small biopsy specimen at frozen-section examination may not be diagnostic.

METHODS

From 1982 to 1992, 416 unselected patients (309 women and 107 men) with primary HPT without familial HPT or multiple endocrine neoplasia (MEN) were treated by one surgeon at the University of California at San Francisco. Double adenoma occurred in 49 patients, solitary adenoma in 309 patients, and hyperplasia in 58 patients. The authors analyzed the clinical manifestations, the preoperative and postoperative serum levels of calcium, phosphate, and parathyroid hormone (PTH), and the success rate and outcome after parathyroidectomy and compared their results in 49 patients with double adenomas to the results for patients with solitary adenomas or hyperplasia.

RESULTS

Ten of the patients with double adenomas (20.4%) were referred for persistent HPT after removal of one abnormal parathyroid gland. The ages of the patients with double adenoma, single adenoma, and hyperplasia were 61 +/- 14, 56 +/- 15, and 58 +/- 7 years, respectively. Fatigue, muscle weakness, and bone pain were common in patients with double adenomas, whereas nephrolithiasis occurred more frequently in patients with solitary adenoma (p = 0.0001). Serum calcium and PTH levels (per cent of upper limit of normal) fell from 11.5 +/- 1.2 mg/dL and 487% to 9.5 +/- 0.8 mg/dL and 61% for patients with double adenomas; from 11.9 +/- 0.9 mg/dL and 378% to 9.3 +/- 1.4 mg/dL and 101% for patients with single adenoma; and from 10.9 +/- 0.5 mg/dL and 418% to 9.1 +/- 0.7 mg/dL and 94% for patients with hyperplasia, respectively. There was no recurrence in the patients with double adenomas with a mean follow-up time of 5.8 years.

CONCLUSIONS

Double adenomas are a discrete entity and occur more often in older patients. Patients with double adenomas can be successfully treated by removal of the two abnormal glands.

Isolation of STD1, a high-copy-number suppressor of a dominant negative mutation in the yeast TATA-binding protein

The TATA-binding protein (TBP) is an essential component of the transcriptional machinery of all three nuclear RNA polymerase enzymes. Comparison of the amino acid sequence of TBPs from a number of species reveals a highly conserved 180-residue C-terminal domain. In contrast, the N terminus is variable in both size and amino acid sequence. Overexpression of a TBP protein with a deletion of the nonconserved N terminus (TBP delta 57) in Saccharomyces cerevisiae results in a dominant negative phenotype of extremely slow growth. Associated with the slow-growth phenotype are defects in RNA polymerase II transcription in vivo. We have screened a high-copy-number yeast genomic library for suppression of the slow-growth phenotype and have isolated plasmids which encode suppressors of TBP delta 57 overexpression. Here we report the sequence and initial characterization of one suppressor, designated STD1 for suppressor of TBP deletion. The STD1 gene contains a single continuous open reading frame with the potential to encode a 50.2-kDa protein. Disruption of the STD1 gene indicates that it is not essential for vegetative growth, mating, or sporulation. High-copy-number suppression by the STD1 gene is not the result of a decrease in TBP delta 57 protein accumulation or DNA-binding activity; instead, STD1 suppression is coincident with the elimination of TBP delta 57-induced RNA polymerase II defects in both uninduced and induced transcription in vivo.