Reversal of refractory hypotension in septic shock by inhibitor of nitric oxide synthase

Septic shock is a life-threatening condition that results from exposure to bacterial endotoxin. It is mediated by the release of cytokines. Some of these cytokines cause the release of vasoactive substances. We report the case of a 62-year-old male patient who received redo operation for replacement of the degenerative porcine aortic and mitral prostheses. High cardiac output shock developed on the seventh postoperative day with severe metabolic acidosis and oliguria. Systemic vascular resistance and mean arterial pressure elevated within 5 min and stabilized 60 min after the start of a single dose of intravenous administration of NG-monomethyl-L-arginine (50 mg), a potent and selective inhibitor of nitric oxide synthesis. These findings indicate that nitric oxide overproduction is an important contributor to refractory hypotension in high cardiac output septic shock. Our findings suggested the utilization of nitric oxide synthase inhibitor in the treatment of septic shock in humans.

Immunosuppressive effects of azelastine hydrochloride on contact hypersensitivity and T-cell proliferative response: a comparative study with FK-506

Azelastine hydrochloride (AZE) is an anti-allergic drug that inhibits the release of various chemical mediators from mast cells. We compared the immunosuppressive effects of AZE and FK-506 in vivo and in vitro. Topical application of AZE strongly inhibited the efferent phase of contact hypersensitivity, as did application of FK-506. In in vitro experiments, we found that 1) the suppression by AZE on interleukin (IL)-2 production from splenic T cells was partial and considerably large amounts of IL-2 were still produced, even in the presence of 10(-5) M of AZE, which was in sharp contrast to the observed marked inhibition of [3H]-TdR incorporation; 2) AZE significantly inhibited the phorbol myristate acetate-induced IL-2 responsiveness; 3) AZE did not inhibit the IL-2 receptor alpha expression of activated T cells; and 4) the significant inhibitory action was still observed even when AZE was added at 48 h after the initiation of culture. In regard to FK-506, we found that 1) FK-506 completely blocked the production of IL-2; 2) exogeneous IL-2 consistently restored the FK-506-induced inhibition; 3) FK-506 affected the phorbol myristate acetate-induced IL-2 responsiveness very little, if any; and 4) the significant suppression was observed only when FK-506 was added within 24 h after the initiation of culture. Thus, AZE exerts its in vitro immunosuppressive activity preferentially by interfering with the IL-2 responsiveness, with partial inhibition of IL-2 production. Conversely, FK-506 acts as a strong inhibitor of IL-2 production without a prominent effect on IL-2 responsiveness. The immunosuppressive activity of AZE shown in vitro may also be operative in vivo and may be applicable for topical use.

Gastric arteriolar and venular responses to nitrogenous and nonnitrogenous vasodilating agents in the rat

We made in vivo microvascular observations to simultaneously compare the actions of various direct vasodilators on the resistance and capacitance vessels without confounding systemic hemodynamic effects. The responses of gastric submucosal arteriolar and venular diameters to the topical application of 10(-7) 10(-5), and 10(-3) M of the vasodilators nitroglycerin (NTG), sodium nitroprusside (SNP), hydralazine (HYD), and adenosine (ADN), and acetylcholine (ACh) were studied in 6 rats for each agent using in vivo microscopy. The basal diameters of arterioles, 37 +/- 2 microns (mean +/- SE), were maximally dilated to 86 +/- 2 microns by 10(-3) M ADN, NTG, SNP or ACh, while with 10(-3) M HYD dilation was just 55%. The basal diameters of venules, 36 +/- 2 microns, were maximally dilated only to 51 +/- 1 micron by 10(-3) M ADN, NTG or SNP, while those by 10(-3) M HYD and ACh were 60 and 71%, respectively. We observed that: (1) NTG and SNP were the strongest arteriolar and venular dilators, but at low dose (10(-7) M), NTG was more effective than SNP. (2) Gastric submucosal venules had considerably less dilating capacity than arterioles. (3) ADN was as effective as NTG and SNP for both arteriolar and venular dilation at 10(-3) M. It was less potent at lower concentrations. (4) ACh was as potent as ADN, NTG and SNP in dilating arterioles, but it was notably less potent in dilating venules. (5) HYD was the weakest arteriolar and venular dilator among all agents studied, and its action on venules was slightly greater than that on arterioles.

Why are children hospitalized? The role of non-clinical factors in pediatric hospitalizations

OBJECTIVE

Pediatric medical discharge rates vary widely across hospital service areas, beyond differences explained by chance or disease incidence alone. This study examines the relationship between the characteristics of local medical services and the likelihood of hospitalization.

DESIGN

Small area and population-based regression analysis.

SETTING

The 72 hospital service areas of Maine, New Hampshire, and Vermont.

STUDY POPULATION

The 589,290 (1989) children of Maine, New Hampshire, and Vermont < 15 years of age with 120,806 discharges during 1985 through 1989.

MEASUREMENT AND MAIN RESULTS

Using logistic regression and controlling for community income, we found that children residing in zip codes with high per capita bed supply (4.0/1000) had 9% more discharges (odds ratio: 1.09; 99% confidence interval: 1.07, 1.11) compared with children in areas with low per capita bed supply (1.9/1000). Children living 30 minutes from the nearest hospital had 15% fewer medical discharges (odds ratio: 0.849; confidence interval: 0.830, 0.867) than those living in a zip code with a hospital. Residence in one of the three academic medical center hospital service areas resulted in 32% fewer discharges (odds ratio: 0.68; confidence interval: 0.66, 0.70). Similar and statistically significant (P < .01) results were noted for the most common nonperinatal diagnostic categories: asthma/bronchitis (diagnostic related group = 98) and gastroenteritis (diagnostic related group = 184). No effect was noted for femur fracture, a condition for which admission rates equal disease incidence.

CONCLUSIONS

The supply and character of medical care are important influences on the likelihood of hospitalization for pediatric medical conditions for which outpatient alternatives are available.

RNA transcription in porcine skeletal muscle nuclei during postnatal development

Postnatal developmental pretranslational regulation of skeletal muscle alpha-actin gene expression was investigated. Northern blot analysis of skeletal muscle alpha-actin and beta-tubulin mRNA from 1- and 28-day-old pigs indicated that there are developmental increases in alpha-actin mRNA abundance (P < 0.03) and no significant changes in beta-tubulin mRNA (P > 0.1). A system for isolation of nuclei from porcine skeletal muscle and for transcriptional "run-on" analysis was established in order to investigate the regulatory mechanism of developmental changes in porcine skeletal muscle protein. Skeletal muscle nuclei were isolated from longissimus dorsi (LD) muscle of 1- and 28-day-old pigs by adapting a method to isolate nuclei from cardiac muscle. Results from a [3H]-UTP incorporation assay indicate that these nuclei preparations have the capacity to synthesize RNA and attain maximum incorporation after 40-45 min at 26 degrees C. Messenger RNA syntheses from skeletal muscle nuclei from 1- and 28-day-old pigs were not significantly different (P > 0.25). All nascent tRNA, rRNA, and mRNA in the nuclei were elongated since [3H]-UTP incorporation was reduced after addition of 0.05 micrograms/ml alpha-amanitin to the transcription mixture. Transcription "run-on" assay results indicated that more (P < 0.02) skeletal muscle alpha-actin pre-mRNA was synthesized in the 28-day-old pig skeletal muscle nuclei than in the 1-day-old pig skeletal muscle nuclei. These results indicate that the relative increase in skeletal muscle alpha-actin mRNA observed in the older animals was due, at least in part, to an increase in the transcriptional activity of the skeletal muscle alpha-actin gene.

Host recognition by the VirA, VirG two-component regulatory proteins of agrobacterium tumefaciens

Agrobacterium tumefaciens contains about 25 vir genes localized on a 200-kb tumour-inducing (Ti) plasmid that direct a conjugation-like transfer of tumorigenic DNA from the bacterium to the nuclei of infected plant cells. These genes are strongly and coordinately induced during infection in response to three different classes of stimuli which are thought to be key chemical features of a typical wound site. These stimuli are (i) guaiacol and syringol derivatives such as acetosyringone, (ii) sugars such as glucose and glucuronic acid, and (iii) acidic pH. The sensing of these compounds is carried out by the VirA, VirG and ChvE proteins. VirA is a four-domain histidine protein kinase, while VirG is a transcriptional activator which is activated by VirA-mediated phosphorylation. ChvE is a chromosomally encoded periplasmic sugar binding protein which is required for sensing sugars but dispensable for sensing the other two stimuli. Here we will review the nature of these chemical stimuli, the structure and function of the three regulatory proteins, their similarity to sensors found in human and animal pathogens, the factors influencing their pool size, and their role in the host range of different strains of A. tumefaciens.

Characterization of the release of cholecystokinin from a murine neuroendocrine tumor cell line, STC-1

The murine neuroendocrine cell line, STC-1, was found to contain 296.8 +/- 1.8 fmol of cholecystokinin-like immunoreactivity (CCK-LI) per mg cell protein. Immunocytochemical stain of STC-1 cells maintained in monolayer culture indicated that CCK-LI activity was present in 93% of the cells. Analysis by reverse-phase high-performance liquid chromatography indicated that STC-1 cells contained CCK-8 and an unidentified form as the predominant storage form. form. However, only CCK-8 was released into the culture medium upon stimulation by various secretagogues. The release of CCK-LI from STC-1 cells was stimulated by dibutyryl cAMP, forskolin, KCl, A23187, 4 beta-phorbol 12-myristate 13-acetate and luminal stimulants, e.g., sodium oleate, L-tryptophan, camostat and plaunotol. The release of CCK-LI from STC-1 cells was also stimulated by a neuropeptide, bombesin. The stimulatory effects of most of these agents were dose dependent. The stimulatory effects of dibutyryl cAMP, forskolin, and plaunotol were potentiated by 3-isobutyl-1-methyl xanthine, while that of camostat was not. The results obtained in this study indicate that the release of CCK from STC-1 cells shares the same characteristics of CCK release as from the CCK-secreting cells of the intestinal mucosa observed both in the dog and the rat in vitro and in vivo. Thus, the cellular mechanism of CCK release which appears to be cAMP- and Ca(2+)-dependent may be modulated by cellular protein kinase C activity. The STC-1 cell appears to be a suitable model for studying the mechanism of CCK release.

Treatment of acute type A aortic dissection with intraluminal sutureless prosthesis

Sutureless intraluminal aortic graft has been used for substitution of aorta, with the advantages of decreasing the aortic cross-clamp time and decreased blood loss. From January 1991 to December 1992, 10 consecutive patients underwent emergency operations to repair acute type A aortic dissection in which sutureless intraluminal grafts were used for replacement of ascending aorta. There were 5 men and 5 women, with ages that ranged from 40 to 74 years (mean, 51 years). The inclusion method was used in all patients. Modified Cabrol shunts were created in 7 patients. Dacron graft (Meadox Medicals, Inc, Oakland, NJ) was used to wrap the ascending aorta in 7 patients. The circulatory arrest time was 33 +/- 13 (mean +/- standard deviation) minutes, and the cardiac ischemic time was 64 +/- 17 minutes. Retrograde superior vena cava cerebral perfusion during circulatory arrest was performed on 4 patients. All patients survived. One patient had a minor stroke and pneumonia with complete recovery. There was no evidence of pseudoaneurysm formation, graft erosion, graft migration, or aortic bleeding in the postoperative period. No patients had permanent renal deficit. Follow-up (1 to 22 months; mean, 9.6 months) of all patients revealed satisfactory graft function, with no device-related deaths and no known complications attributable to the prosthesis, such as thrombosis, erosion, pseudoaneurysm formation, or hemorrhage. Our experience suggests that grafting of the ascending aorta is less hazardous with the sutureless grafts than with the conventional sutured anastomosis technique. We are now using this method whenever possible in all substitutions of the aorta.

Primary malignant lymphoma of the uterine cervix shows favorable response to neoadjuvant chemotherapy

Primary malignant lymphoma localized in the uterine cervix is a rare condition for which radiation therapy, surgery, or chemotherapy either alone or in combination have been the mainstay of treatment. The effectiveness of neoadjuvant chemotherapy for this condition, however, has not been evaluated. We experienced one case of primary malignant lymphoma of the uterine cervix, stage IIa according to FIGO, and IEA according to the Ann Arbor staging system for extranodal lymphomas, which was treated with neoadjuvant chemotherapy and surgery. The patient first underwent neoadjuvant chemotherapy consisting of cyclophosphamide, vinblastine, epirubicin, bleomycin, procarbazin, and oncovin (COP-BLAM) to reduce the size of the tumor. This was followed by an extended total hysterectomy, left salpingo-oophorectomy, and bilateral pelvic lymph node dissection. Neoadjuvant chemotherapy given before surgery resulted in a remarkable reduction in the tumor size which made the subsequent surgery technically easy. In addition, it is possible that intraoperative micrometastasis of the tumor cells could be better prevented. The patient received additional chemotherapy with COP-BLAM schedules postoperatively. No evidence of recurrent lymphoma has been observed in 2 years after the treatment. Neoadjuvant chemotherapy may be an effective treatment modality for primary malignant lymphoma of the uterine cervix.

Use of Gore-Tex sling in brow suspension procedure

A variety of materials have been employed for brow suspension surgery for ptosis. Gore-Tex (expanded polytetrafluoroethylene ePTFE) has been used as vascular prosthesis. We have used cylinder Gore-Tex in brow suspension surgery for 15 ptotic eyelids (11 patients), including 10 eyes (8 patients) of congenital ptosis, 1 eye of traumatic ptosis in a young male, and 4 eyes (2 patients) of myogenic ptosis in elderly patients. All of the eyelids had minimal or absent levator muscle function, and drooped to cover the visual axes. The surgical technique for the 10 congenital ptotic eyelids was a modified Fox's method. The remaining 5 adult eyelids were operated by a modified Crawford's method, with interlocking of the two suspension bands at the lower apex of each triangle and direct suturing of the bands to the tarsal plate. The use of Gore-Tex in brow suspension makes it easy to adjust the height and contour of the operated eyelids. Patients were followed-up from 2 to 16 months (average 9.1 months) postoperatively. The only complication was granuloma formation at the most upper knot area in 5 patients (6 eyelids), one of which also had granuloma at the ipsilateral fornix with the Gore-Tex band cutting through the conjunctiva. One eyelid drooped due to knot granuloma and infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term results of polytetrafluoroethylene mitral annuloplasty

Prosthetic rings are customarily used for mitral annuloplasty to plicate and reinforce the annulus and keep the annulus from further dilating. From July 1984 to March 1992, mitral annular plication using polytetrafluoroethylene (PTFE) graft material was performed on 73 patients (age range, 15 to 69 years; mean, 35.7 years) with mitral regurgitation. The cause of the mitral regurgitation was rheumatic in 50.7% and degenerative in 36.9% of the patients. After other repair procedures on the mitral valve apparatus had been performed, a PTFE graft (3 mm) was tailored to the length of the free edge of the anterior leaflet and then inserted at the posterior part of the mitral annulus between the commissures. The operative mortality was 2.7%. Follow-up ranged from 0.7 to 8.5 years (mean, 5.6 years). Postoperative echocardiography confirmed that 94.2% of the survivors had either no or only mild mitral regurgitation with a large mitral valve area (2.7 +/- 0.3 cm2) and almost no pressure gradient across the mitral valve or left ventricular outflow tract. Two patients successfully underwent redo PTFE mitral annuloplasty. Two patients died, one 15 and the other 20 months later, due to myocardial failure, with no mitral regurgitation. The event-free survival rate was 90% +/- 4% at 8 years. We conclude that PTFE mitral annuloplasty is an effective procedure that yields good long-term results.

The changes of ocular axial length and corneal curvatures after scleral buckling for retinal detachment

As myopia plays an important role in the pathogenesis of retinal detachment, alterations of refractive components after scleral buckling procedures for retinal detachment may be an important factor for retinal redetachment. To find out the refractive change following retinal detachment surgery, we prospectively followed up the alterations of corneal curvature, and axial components (axial length, anterior chamber depth, lens thickness, and vitreous length) of 44 eyes of rhegmatogenous retinal detachment before and after operations. The procedures consisted of encircling scleral buckling (12 eyes) and segmental scleral buckling (32 eyes). All patients were followed for 6 months postoperatively. The corneal curvatures were measured with a keratometer, the axial length and axial components were measured with an A-scan ultrasonography. The methods and materials used in operation were recorded in detail to correlate with the refractive changes. The corneal curvature showed a trend to flatten early after operation (the 1st week), and gradually reversed to steepening. But, the difference was statistically significant only at the K2 (vertical meridian) in the 1st postoperative week and the K1 (horizontal meridian) in the 4th postoperative week. Lengthening of eyeballs were noted in the encircling group (12 eyes), but only the elongation in the 1st postoperative week was statistically significant. While in segmental buckling group, the axial length of the eyeballs was transiently shortened. The shortening was significant in the 2nd, 4th, and 6th week after operation. The reduction of eyeball's axial length was related to the shortening of vitreous length and shallowing of anterior chamber.(ABSTRACT TRUNCATED AT 250 WORDS)

Intractable nontuberculous mycobacterial keratitis successfully treated by penetrating keratoplasty--3 cases report

Since the first diagnosis of nontuberculous mycobacterial keratitis in Taiwan on 1983 by Chen et al., we have collected another 70 cases. Although most of the cases were difficult to treat medically, almost all cases healed before optical penetrating keratoplasties were performed. But, three of these cases responded poorly to medical treatment with sporadical relapse. Finally, penetrating keratoplasties (PKP) were performed on these three cases. These three cases were all males, aged 48, 27, and 35 respectively. The durations from the onset to receiving PK were 10, 4, and 6 months. All had histories of corneal trauma and all cases responded poorly or inconsistently to topical amikacin, erythromycin and antituberculous drugs. Histopathological examination of the diseased corneas in the first chronic case showed granuloma formation in the area of ulcer base. The second case presented lymphocyte clustering in the subepithelial region. The third case, which was operated in a relatively inflamed stage, had lymphocytes infiltrating the whole layer of the cornea. The results of PKP in the three eyes were therapeutically and optically successful, though the second case failed in the first penetrating keratoplasty due to acute tissue failure without recurrent infection. The best corrected visual acuities in the three eyes, postoperatively, were 20/25, 20/40, and 20/100 respectively. With the successful experience of these three cases, we suggest that performing PKP for intractable nontuberculous mycobacterial keratitis at an early stage may reduce the duration of the patients' suffering.

Comparison of five modalities in localization of primary aldosteronism

BACKGROUND

The best response to surgical treatment of primary aldosteronism occurs in patients with an aldosterone-producing adenoma (APA), so pre-operative localization of the lesion is necessary.

METHODS

A comparison was made of five localizing modalities-computed tomography (CT) of the adrenal gland, magnetic resonance imaging (MRI), dexamethasone suppression-131I-19-cholesterol adrenal scintiscan (DS, NP-59 adrenal scan), adrenal venography (venography) and adrenal venous sampling for aldosterone content (AVS) in 22 patients (12 women, 10 men) with primary aldosteronism; all had undergone operative confirmation within the past 9 years. The age at diagnosis ranged from 27 to 67 years (mean: 39.7).

RESULTS

Unilateral adrenalectomy resulted in normal blood pressure without medication in 63.6% (14/22), and in improvement in 36.4% (8/22). Correct localization of the lesion was obtained in 95% (20/21) by CT, 100% (7/7) by MRI, 80% (12/15) by DS,NP-59 adrenal scan, 100% (6/6) by AVS and 78% (7/9) by venography.

CONCLUSIONS

This experience would advocate CT of the adrenals as the initial means of localizing an APA on an outpatient basis because it is comfortable, safe, inexpensive and gives immediate results. The major role of MRI in the evaluation of adrenal adenoma should be complementary to CT. DS, NP-59 adrenal scan can be an adjuvant method for localization if CT scan results are not definitive. Adrenal venous catheterization with blood sampling for aldosterone content could be reserved for patients whose biochemical finging suggests the presence of an APA, and for whom CT or MRI of the adrenals and DS, NP-59 adrenal scan are inconclusive.

University of Wisconsin solution extends lung preservation after prostaglandin E1 infusion

University of Wisconsin (UW) solution has been demonstrated to enhance and extend the preservation of the hepatic, pancreatic, renal, and cardiac allografts. Prostaglandin E1 (PGE1), which has been used to produce pulmonary vasodilatation, has improved preservation in lung transplantation. Experiments were designed to evaluate their potential role in 24-h preservation of the allografts in lung transplantation. Thirty-six dogs underwent left lung transplantation. The donor lungs (n = 6 in each group) were flushed with UW solution (group 1 and 2) or modified Euro-Collins (EC) solution (group 3) after PGE1 infusion (500 micrograms). In group 1, donor lungs were transplanted immediately. Lung allografts of group 2 and 3 were cold stored (4 degrees C) in the same preservation solution for 24 h in the inflated state and then transplanted. The right pulmonary artery and right main bronchus were ligated 1 h after completion of the transplantation, forcing the recipient dogs to survive with the transplanted left lung. The recipients were ventilated with an inspired oxygen fraction of 0.4 and end-expiratory pressure 10 cm H2O. Two dogs died prematurely in group 3, whereas all dogs in group 1 and 2 survived the experimental period. The arterial oxygen tension and saturation and dynamic lung compliance were significantly higher in dogs of group 1 and 2. Transplanted lungs of group 1 and 2 had significantly lower pulmonary vascular resistance, alveolar-arterial oxygen difference, and wet/dry lung weight ratio. Histologically, pulmonary edema, congestion, sloughing of bronchial mucosa, and peribronchial and peripulmonary arterial hemorrhage were shown in lungs of group 3, but not in those of group 1 and 2. Airway mucosa and pulmonary vascular structure were well preserved in lungs of group 1 and 2. There was no significant difference between group 1 and 2 in lung functions, hemodynamics, or morphologic features. We concluded that PGE1 and UW solution could effectively extend lung preservation up to 24 h in this in vivo canine lung allotransplantation model.

[The hemodynamic and ventilatory effects between Trendelenburg and reverse Trendelenburg position during laparoscopy with CO2-insufflation]

Thirty ASA class I female patients underwent gynecologic pelvioscopy and laparoscopic cholecystectomy were included in this study. All of them received general anesthesia and certain volume of CO2 pneumoperitoneum. We evaluated the effect of positioning (Trendelenburg as group I and reverse Trendelenburg as group II) on hemodynamic parameters and ventilation. The hemodynamic parameters, ventilation, and arterial blood gas were determined at the following stages: (1) after 10 minutes of normoventilation and before CO2 pneumoperitoneum (as control), (2) 5 minutes after CO2 pneumoperitoneum and positioning, (3) 25 minutes after positioning, (4) 50 minutes after positioning, (5) 10 minutes after resumption of supine position and decompression of abdomen. Arterial blood pressure, heart rate, minute volume, end-tidal CO2, oxygen saturation and blood gas analysis were taken during normoventilation. We found that there was no statistical difference between either group in respect to hemodynamic parameters. For the ventilation, both groups had appropriate SpO2 during the period of CO2 pneumoperitoneum, but PaCO2 was significantly increased in group I 25 min after CO2 pneumoperitoneum and Trendelenburg positioning. Nonetheless, end-tidal CO2 was not significantly increased. pH value and PaCO2 did respectively decrease and increase significantly in group I 50 min after Trendelenburg position. However, no change was found in end-tidal CO2. All data were not significantly different after resumption of supine position and decompression of abdomen. Conclusively, except that pH and PaCO2 had changed after a period of Trendelenburg positioning with CO2 pneumoperitoneum, the patients who underwent laparoscopic surgery with normoventilation have no hemodynamic and respiratory change.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural requirements of mastoparan for activation of membrane-bound guanylate cyclase

Mastoparan activated membrane-bound guanylate cyclase and potentiated the effect of atrial natriuretic factor (ANF) and ATP on guanylate cyclase activity in rat lung membranes. Mastoparan is a cationic, amphiphilic tetradecapeptide with an amidated carboxyl terminus. It takes the alpha-helical conformation upon interacting with the membrane. Several analogs were synthesized to study the role of the positive charges, the carboxyl amino group and the alpha-helical conformation of mastoparan in the activation of guanylate cyclase. The results showed that substitution of the C-terminal amide group of mastoparan with a carboxyl group significantly reduced its potency on the activation of guanylate cyclase. Replacement of three lysine residues of mastoparan with aspartic acid or serine residues completely abolished the stimulatory effect of mastoparan. When the alanine at position 10 of mastoparan was substituted by a proline, the resulting analog had no effect on guanylate cyclase activity. These results demonstrate that the positive charges and the helical structure of mastoparan are critical determinants for the activation of guanylate cyclase.

A tetrazolium-based(MTT) assay for measuring viability of cultured porcine corneal endothelium

A tetrazolium-based(MTT) assay was used to evaluate the viability of cultured porcine monolayer corneal endothelial cells. In this study, we tried to find out the best spectra at which scanning multiwell ELISA spectrophometer can obtain the widest range of absorbance (optical density, O.D.) and the ranges of numbers of corneal endothelial cells in which absorbance is in a significant linear relationship with cell numbers. Among the three tested spectra of 450, 540, and 630nm, the widest range of absorbance was at 540 nm, from 0.1193 to 0.6183. At all three tested spectra, numbers of corneal endothelial cells from 50 to 30,000 were in a significant linear relationship with absorbance. Therefore, in the future studies to assay the viability of corneal endothelial cells, we shall choose the spectrum of 540 nm for reading with a scanning multiwell ELISA spectrophotometer, and absorbance(O.D.) from 0.1193 to 0.6183 will be accepted, representing cell numbers from 50 to 30,000.

Video-assisted thoracic surgery. Manipulation without trocar in 112 consecutive procedures

Since learning of the video-assisted thoracoscopic techniques in the treatment of thoracic diseases, we have encountered many problems and difficulties because of the limited trocar space and lack of suitable instrumentations. Since March 1992, we have found a simple and easier way to perform this procedure, that is, manipulating through the extended incisional wound without using a trocar. Endoscopic and conventional thoracic instruments are able to pass through the incisional channel freely and manipulate similarly to the technique used in open thoracotomy. All the patients had less postoperative pain, reduced operative time, and prompt return to employment. The technique is effective and is herein described.

Nitric oxide in the sensory function of the carotid body

Recent studies suggest that nitric oxide (NO) may act as a chemical messenger in the nervous system. Since neurotransmitters are considered necessary for the sensory function of the carotid body, and molecular O2 is a co-factor for NO synthesis, we examined whether (a) chemoreceptor tissue also synthesizes NO and if so, (b) does endogenous NO affect chemosensory activity. Experiments were performed on carotid bodies obtained from anesthetized cats (n = 20). Distribution of nitric oxide synthase (NOS), an enzyme that catalyzes the formation of NO was examined using NADPH-diaphorase histochemistry. Many nerve plexuses innervating the chemoreceptor tissue were positive for NADPH-diaphorase, indicating that the nerve fibers are the primary source of NO production in the carotid body. Radiometric analysis of NOS activity of the chemoreceptor tissue averaged 1.94 pmol [3H]citrulline/min/mg protein. NOS activity was significantly less in low pO2 reaction medium than in room air controls. Chemosensory activity in vitro increased in a dose-dependent manner in response to L-omega-nitro arginine (L-NNA), an inhibitor of NOS activity. The effects of NOS inhibitor were enantiomer selective as evidenced by reversal of the responses by L- but not D-arginine. These observations imply that endogenous NO is inhibitory to carotid body sensory activity. cGMP levels of L-NNA-treated carotid bodies were significantly less than untreated controls, suggesting that the actions of NO are coupled to the cGMP second messenger system, as elsewhere in the nervous system.(ABSTRACT TRUNCATED AT 250 WORDS)

Site-specific and compensatory mutations imply unexpected pathways for proton delivery to the QB binding site of the photosynthetic reaction center

In photosynthetic reaction centers, a quinone molecule, QB, is the terminal acceptor in light-induced electron transfer. The protonatable residues Glu-L212 and Asp-L213 have been implicated in the binding of QB and in proton transfer to QB anions generated by electron transfer from the primary quinone QA. Here we report the details of the construction of the Ala-L212/Ala-L213 double mutant strain by site-specific mutagenesis and show that its photosynthetic incompetence is due to an inability to deliver protons to the QB anions. We also report the isolation and biophysical characterization of a collection of revertant and suppressor strains that have regained the photosynthetic phenotype. The compensatory mutations that restore function are diverse and show that neither Glu-L212 nor Asp-L213 is essential for efficient light-induced electron or proton transfer in Rhodobacter capsulatus. Second-site mutations, located within the QB binding pocket or at more distant sites, can compensate for mutations at L212 and L213 to restore photocompetence. Acquisition of a single negatively charged residue (at position L213, across the binding pocket at position L225, or outside the pocket at M43) or loss of a positively charged residue (at position M231) is sufficient to restore proton transfer activity to the complex. The proton transport pathways in the suppressor strains cannot, in principle, be identical to that of the wild type. The apparent mutability of this pathway suggests that the reaction center can serve as a model system to study the structural basis of protein-mediated proton transport.