[Endoscopic totally visceral sac separation for ventral hernias repair: anatomy notes and technical considerations]

The abdominal wall can be treated as a whole physiological and functional entity which is composed of multiple anatomical structures and planes. Surgical approaches and technical details that required are diverse in different area. Indeed, the abdominal wall is confined by several anatomical boundaries which make these surgical planes separated. If one could dissect these boundaries, then separated spaces could be connected, establishing an ample retromuscular/preperitoneal space to accommodate the mesh of ventral hernia repair. The concept of totally visceral sac separation (TVS) is achieved. The TVS concept is a summary of diverse ventral hernia repair techniques. Since its initiation and spread, this technique has been widely accepted and implemented by domestic surgeons due to its outstanding performance. This treatise will review the relevant anatomy as well assurgical tricks by the authors that aid in performing TVS. Some of the details are more tricky and harder to understand, thus this in-depth description of the technique.

Costal cartilage grafting in the treatment of concurrent osteochondral lesion of the talus in a trimalleolar fracture

A 49-year-old female sustained a trimalleolar fracture concurrent with 10 years history of symptomatic osteochondral lesions of the talus. We performed a costal cartilage grafting for osteochondral lesions of the talus through the inherent medial malleolar fracture gap, followed by internal fixation of the fracture. During the follow-up, the fracture healed within the expected time, accompanied by favorable functional outcomes and pre-injury pain relief. At 3 years postoperatively, the graft merged with the bone bed of the talus, and progressive endochondral ossification was observed at the graft-bone interface. The case provides us a chance to verify whether the costal cartilage grafting is reliable for the treatment of osteochondral lesions of the talus.

Autologous Costal Cartilage Grafting for a Large Osteochondral Lesion of the Femoral Head: A 1-Year Single-Arm Study with 2 Additional Years of Follow-up

BACKGROUND

There is currently no ideal treatment for osteochondral lesions of the femoral head (OLFH) in young patients.

METHODS

We performed a 1-year single-arm study and 2 additional years of follow-up of patients with a large (defined as >3 cm 2 ) OLFH treated with insertion of autologous costal cartilage graft (ACCG) to restore femoral head congruity after lesion debridement. Twenty patients ≤40 years old who had substantial hip pain and/or dysfunction after nonoperative treatment were enrolled at a single center. The primary outcome was the change in Harris hip score (HHS) from baseline to 12 months postoperatively. Secondary outcomes included the EuroQol visual analogue scale (EQ VAS), hip joint space width, subchondral integrity on computed tomography scanning, repair tissue status evaluated with the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, and evaluation of cartilage biochemistry by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping.

RESULTS

All 20 enrolled patients (31.02 ± 7.19 years old, 8 female and 12 male) completed the initial study and the 2 years of additional follow-up. The HHS improved from 61.89 ± 6.47 at baseline to 89.23 ± 2.62 at 12 months and 94.79 ± 2.72 at 36 months. The EQ VAS increased by 17.00 ± 8.77 at 12 months and by 21.70 ± 7.99 at 36 months (p < 0.001 for both). Complete integration of the ACCG with the bone was observed by 12 months in all 20 patients. The median MOCART score was 85 (interquartile range [IQR], 75 to 95) at 12 months and 75 (IQR, 65 to 85) at the last follow-up (range, 24 to 38 months). The ACCG demonstrated magnetic resonance properties very similar to hyaline cartilage; the median ratio between the relaxation times of the ACCG and recipient cartilage was 0.95 (IQR, 0.90 to 0.99) at 12 months and 0.97 (IQR, 0.92 to 1.00) at the last follow-up.

CONCLUSIONS

ACCG is a feasible method for improving hip function and quality of life for at least 3 years in young patients who were unsatisfied with nonoperative treatment of an OLFH. Promising long-term outcomes may be possible because of the good integration between the recipient femoral head and the implanted ACCG.

LEVEL OF EVIDENCE

Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

The burden of end-stage osteoarthritis in Australia: a population-based study on the incidence of total knee replacement attributable to overweight/obesity

OBJECTIVES

To determine the risk of total knee replacement (TKR) for primary osteoarthritis (OA) associated with overweight/obesity in the Australian population.

METHODS

This population-based study analyzed 191,723 cases of TKR collected by the Australian Orthopaedic Association National Joint Registry and population data from the Australian Bureau of Statistics. The time-trend change in incidence of TKR relating to BMI was assessed between 2015 and 2018. The influence of obesity on the incidence of TKR in different age and gender groups was determined. The population attributable fraction (PAF) was then calculated to estimate the effect of obesity reduction on TKR incidence.

RESULTS

The greatest increase in incidence of TKR was seen in patients from obese class III. The incidence rate ratio for having a TKR for obesity class III was 28.683 at those aged 18-54 years but was 2.029 at those aged >75 years. Females in obesity class III were 1.7 times more likely to undergo TKR compared to similarly classified males. The PAFs of TKR associated with overweight or obesity was 35%, estimating 14,287 cases of TKR attributable to obesity in 2018. The proportion of TKRs could be reduced by 20% if overweight and obese population move down one category.

CONCLUSIONS

Obesity has resulted in a significant increase in the incidence of TKR in the youngest population in Australia. The impact of obesity is greatest in the young and the female population. Effective strategies to reduce the national obese population could potentially reduce 35% of the TKR, with over 10,000 cases being avoided.

Construction of SNP-STR Multiplex Amplification System with Genetic Markers and Its Forensic Application

Abstract

Objective To select and develop a SNP-STR multiplex amplification system with genetic markers compatible with current STR databases. To understand its genetic polymorphisms in Sichuan Han population and its application value in DNA mixture analysis. Methods Based on the STR genetic markers in commercial kits, SNPs adjacent to these STR markers were selected to be SNP-STR genetic markers. A SNP-STR multiplex amplification system with genetic markers based on allele-specific amplification was constructed using allele-specific amplification primers. The genetic polymorphism of the system in the Sichuan Han population was investigated and the efficiency of systems with different numbers of loci to detect the two individual DNA mixture samples was evaluated. Results An allele-specific multiplex amplification system constituted of 13 SNP-STR genetic markers was selected and constructed. In Sichuan Han population, the heterozygosity of each locus ranged from 0.76 to 0.88, and the combined discrimination power reached 0.999 999 999 999 999 968. In the analysis of the two individual DNA mixture samples： for single-locus amplification, the genotype of the minor components can still be detected when the mixture ratio reaches 1 000∶1; for multiple loci multiplex amplification, the maximum mixture ratio can reach 500∶1. As the number of loci in the system increased, the detection efficiency of the minor components in the DNA mixture decreased. Conclusion SNP-STR genetic markers have a higher polymorphism than STR. The multiplex amplification system made of SNP-STR genetic markers has a better analysis efficiency for mixed samples than traditional STR multiplex amplification system.

Radiologic predictor of intraoperative lateral wall fractures in treatment of pertrochanteric fractures with cephalomedullary nailing

Objective

This study was performed to investigate the reliability of the height of pertrochanteric fractures as a predictor of lateral wall fractures after cephalomedullary nailing and provide a simple way to determine the threshold value.

Methods

We performed a prospective randomized clinical study of 50 consecutive patients who underwent measurement of the height of the pertrochanteric fracture and the tangent line to the superior margin of the contralateral femoral neck. The preoperative and postoperative integrity of the lateral wall was evaluated by computed tomography.

Results

The pertrochanteric fracture height was significantly lower in patients with than without intraoperative lateral wall fractures (15.6 vs. 28.5 mm, respectively). The threshold value of the fracture height was 20.445 mm, which was not significantly different from the mean height of the tangent line of the superior margin of the contralateral femoral neck (19.4 mm).

Conclusions

Pertrochanteric fractures with the proximal starting point lower than the mirror position of the tangent line to the superior margin of the contralateral femoral neck have a higher risk of intraoperative lateral wall fractures during cephalomedullary nailing.

Simultaneous dislocation of the radial head and distal radio-ulnar joint without fracture in an adult patient: a case report and review of literature

Background

Simultaneous dislocation of the radial head and distal radio-ulnar joint without fracture (Criss-Cross Injury) in an adult patient is rarely reported in previous studies. The pathological changes and injury patterns have not been clearly demonstrated.

Case presentation

A 26-year-old woman presented with acute pain of the right wrist and elbow after a fall from cycling. Physical examination revealed an unstable elbow and wrist joint. Plain radiographs showed volar dislocation of the radial head and dorsal dislocation of the distal radius without associated fracture, forming a criss-cross appearance of the ulna and radius on the lateral radiograph. MRI images confirmed partial rupture of the proximal interosseous membrane from its dorsal attachment on the radius, as well as partial rupture of the medial collateral ligament. Conservative treatment failed because the radiocapitellar joint and distal radio-ulnar joint could not be simultaneously reduced. Surgical exploration revealed a highly unstable radial head, but the annular ligament was found to be intact. Manual force was applied to reduce the radial head and a percutaneous K-wire was used to stabilize the proximal radioulnar joint with the forearm in full supination. After surgery, the elbow was immobilized in 90° flexion by a long arm cast for 4 weeks. The K-wire was removed at 6 weeks postoperatively. At 18 months postoperatively, the patient had regained a full range of flexion and extension, with normal supination and a slight limitation in pronation.

Conclusions

The proximal IOM, especially the dorsal band, was injured in Criss-Cross injuries, while the central part of the IOM remained intact. This injury pattern distinguished itself from Essex-Lopresti injury, which mainly involves rupture of the central band of the IOM.

[Effect of anesthesia on cardiopulmonary complications in elderly patients with hip fracture]

Objective: To compare the effects of different types of anesthesia on postoperative cardiopulmonary complications in patients aged 80 years and above who received unilateral hip fracture surgery. Methods: The perioperative data of patients aged 80 and above who underwent unilateral hip fracture surgery in Peking Union Medical College Hospital from July 2009 to June 2014 were collected and grouped based on the types of anesthesia including general anesthesia, neuraxial anesthesia, and peripheral nerve block. Variables were analyzed including preoperative general conditions (age, sex, type of fracture, ASA physical status classification, preoperative cardiopulmonary complications), intraoperative conditions (type of surgical procedure, operative time, blood loss, total intraoperative fluid infusion), and postoperative conditions (length of hospital stay, postoperative hospital stay, ICU stay, postoperative newly developed cardiopulmonary complications, postoperative in-hospital death, hospitalization costs). The incidences of postoperative cardiopulmonary complications of each group were analyzed and compared. Results: A total of 219 cases were finally analyzed including general anesthesia (n=46), neuraxial anesthesia (n=90) and nerve block group (n=83). Fewer cases with preoperative pulmonary complications were noticed in general anesthesia group (15 cases, 32.6%) than in neuraxial anesthesia group (45 cases, 50%) and nerve block group (47 cases, 56.6%) (χ(2)=6.912, P=0.032). No statistical differences were found between groups regarding preoperative cardiovascular complications and other variables. There were no significant differences in postoperative cardiopulmonary complications. However, the cost of hospitalization was lower in neuraxial anesthesia group (45.6±21.4) thousand RMB and nerve block group (48.2±25.8) thousand RMB compared with general anesthesia group (56.3±21.6) thousand RMB, the difference was statistically significant(F=9.951, P=0.007). Conclusions: For elderly patients undergoing unilateral hip surgery, the type of anesthesia does not affect the incidence of postoperative cardiopulmonary complications. However, neuraxial anesthesia and nerve block may reduce the cost of hospitalization.

Removal of molybdenum(VI) from aqueous solutions using nano zero-valent iron supported on biochar enhanced by cetyl-trimethyl ammonium bromide: adsorption kinetic, isotherm and mechanism studies

A new carbonized pomelo peel biosorbent (MCPP) modified with nanoscale zero-valent iron (NZVI) and cetyl-trimethyl ammonium bromide was prepared and employed for the adsorption of molybdate (Mo(VI)) from aqueous solution. We investigated the effects of various conditions on Mo(VI) adsorption and evaluated the results based on adsorption kinetics models and isotherm equations. The kinetic data fitted to the pseudo-second-order model. The Langmuir model best described the adsorption of Mo(VI) on MCPP. The values of changes in Gibbs free energy, standard enthalpy, and standard entropy revealed that the adsorption process was feasible, spontaneous and endothermal. X-ray diffraction, Fourier transform infrared and X-ray photoelectron spectroscopy measurements suggested that Mo(VI) adsorption occurred via both the reduction and surface adsorption. Thus, biochar, prepared from fruit residue, can be applied to remove Mo(VI) from aqueous solutions. More importantly, our results provide a sustainable approach for Mo(VI) removal from wastewater by means of functional modification.

[Serum uric acid is associated with disease severity and an important predictor for clinical outcome in patients with pulmonary hypertension]

Objective: The growing body of literature showed a link between uric acid and pulmonary hypertension (PH), but the impact of hyperuremia on outcome of patients with PH has not been well defined. Therefore, the present study was performed to analyze the impact of uric acid on outcome of PH patients. Methods: One hundred seventy-three PH patients (112 females, mean age 38 years old), who were hospitalized in our department between January 2010 and December 2015, were included in our study, the PH diagnosis was made based on right heart catheterization examination result (mean pulmonary artery pressure≥25 mmHg(1 mmHg=0.133 kPa)). PH patients were divided into mild to moderate PH group (Rp/Rs≤0.6, n=97) and severe PH group (Rp/Rs>0.6, n=76). Fifty-one patients (33 females, mean age 45 years old) without PH based on right heart catheterization were included as control subjects. All participants were followed up for a median of 24 months(6-71 months). Clinical endpoints were defined as cardiogenic death or heart-and-lung transplantation. Results: Uric acid was positively correlated with pulmonary vascular resistance(r=0.398, P<0.01), systemic vascular resistance(r=0.244, P<0.01) and mean right atrial pressure (r=0.26, P<0.01), and was negatively correlated with cardiac index(r=-0.278, P<0.01)and mixed venous oxygen saturation (r=-0.322, P<0.01)in PH patients. Serum uric acid level was significantly higher in patients with severe PH than in patients with mild-to-moderate PH and the control subjects (both P<0.05). According to the receiver operating characteristic curve (ROC), 425.5 μmol/L was found to be the best cut-off value of serum uric acid level to predict the outcome of PH patients (sensitivity 50%, specificity 72%). During follow-up, patients with higher level of uric acid (>425.5 μmol/L) were linked with poorer clinical outcome compared to patients with uric acid <425.5 μmol/L(P=0.027). Conclusion: Our findings suggests that uric acid is associated with the severity of PH and higher uric acid level serves as an important predictor for poor clinical outcome of PH patients.

Dihydromethysticin kavalactone induces apoptosis in osteosarcoma cells through modulation of PI3K/Akt pathway, disruption of mitochondrial membrane potential and inducing cell cycle arrest

The objective of the present study was to evaluate the tumor and apoptotic effects of dihydromethysticin kavalactone against human osteosarcoma (MG-63) cells. Antiproliferative activity was measured with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induction by dihydromethysticin was demonstrated by fluorescence microscopy, quantitative videomicroscopy and Annexin V-FITC apoptosis detection kit. Mitochondrial membrane potential disruption was demonstrated by rhodamine-123 dye using flow cytometry. We also evaluated the effect of dihydromethysticin on PI3K/Akt pathway with an immunoblotting analysis. The results showed that the compound induced dose-dependent as well as time-dependent antiproliferative effects against MG-63 cell growth. Cell death and apoptotic body formation was noticed followed dihydromethysticin treatment at various doses. The percentage of apoptotic cells (early apoptosis+late apoptosis) increased from 6.63% in untreated control to 23.92%, 23.81% and 93.9% in 25 µM, 75 µM and 100 µ Mdihydromethysticin-treated cells respectively. Flow cytometric analysis showed dihydromethysticin induced an increase in G0/G1 cells (apoptotic cells). Furthermore, we observed mitochondrial transmembrane depolarization along with decreased phosphorylation levels for PI3K, AKT (Ser 473), AKT (Thr 308), GSK-3β, and BAD. These reductions were associated with down regulation of AKT and upregulation of both GSK-3β and BAD.

Double crush syndrome due to plating of humeral shaft fracture

Median nerve injury is rarely associated with the humeral shaft fracture. A Sixty two year old woman with a displaced humeral shaft fracture, developed a symptomatic carpal tunnel syndrome after plating with a screw protruding medially. 16 months later, the implants were removed and the symptoms gradually improved without carpal tunnel release surgery. A double crush syndrome resulted due to the proximal compression by the medially protruding screw and the distal compression by carpal tunnel. The proximal decompression produced by removal of the screw led to relief of the symptoms.

Posterior coronal plating of bicondylar tibial plateau fractures through posteromedial and anterolateral approaches in a healthy floating supine position

Bicondylar tibial plateau fractures pose a significant challenge for treating surgeons. If the articular surface of the medial plateau has a second split component in the posterior coronal plane, it is difficult to get direct visualization and ensure plate fixation when the patient is in the supine position. Using a technique in which a single preparation and draping of both legs is needed, patients were operated on using a healthy floating supine position maneuver through dual posteromedial and anterolateral incisions and triple plate fixations. By flexing and adducting the contralateral healthy hip over the injured leg, more lateral rotation of the fractured knee can be achieved, providing better access and visualization of the posterior medial plateau using a posteromedial gastrocnemius approach.

Sympathetic preganglionic neurons project to superior cervical ganglion via C7 spinal nerve in pup but not in adult rats

We investigated the distribution of sympathetic preganglionic fibers in each spinal nerve of the brachial plexus, and its correlation with presence of Horner's syndrome in the pup and adult rats. According to surgical intervention to the C7-T1 spinal nerves in the right side, rats of 7 days postnatal (P7), P14 and adulthood (24 for each age group) were subdivided into four subgroups of six each, respectively, i.e., C7 or C8 or T1 spared subgroup--where C7 or C8 or T1 alone was kept intact with avulsion of the other two spinal nerves and division of the sympathetic chain caudal to the stellate ganglion; C7-T1 avulsed subgroup--where C7-T1 were all avulsed but the sympathetic chain kept intact. Fluoro-Gold (FG) was injected bilaterally into the superior cervical ganglion (SCG) for labeling of sympathetic preganglionic neurons (SPNs). Furthermore, Horner's syndrome was examined after avulsion of different spinal nerves for P14 and adult rats. In C7 spared subgroups, FG-labeled neurons accounted averagely for 16.9% in P7, 13.5 in P14 and 1.0 in adult rats, and difference was statistically significant between P7 and adults (Z=-2.9, P=0.004), P14 and adults (Z=-2.9, P=0.004). When both C7 and C8 were avulsed, Horner's syndrome was more prone to be produced in pups than in adults (chi(2)=4.2, P=0.04). These results indicate that some SPNs project to SCG via C7 in the pup, but this pathway disappears during postnatal development. It suggests that in newborns with brachial plexopathy, presence of Horner's syndrome may be correlated with avulsion of C7.

Novel selective cytotoxicity of wild sarsaparilla rhizome extract

Among six fractions, including total extract and fractions of hexane, ethyl acetate, butanol, water and boiling water extracted and separated from wild sarsaparilla rhizome, the hexane fraction (HRW) was the most effective in eliminating four different human cancer cell lines with cellular viability less than 6.8%. HRW exhibited the highest potency against human leukaemia cells with an IC50 (concentration that inhibited the growth rate of cells by 50%) of 3.3 ± 0.3 μg mL−1, which was 17.6-fold smaller than that against normal human umbilical vein endothelial cells (IC50, 58.0 ± 1.5 μg mL−1). For its rich natural resources, simple extraction procedure and high yield (3.2%), HRW has the potential to be developed as a selective anti-cancer nutraceutical or pharmaceutical natural health product with low side effects and high economical return.

Distally based sural fasciomyocutaneous flap: anatomic study and modified technique for complicated wounds of the lower third leg and weight bearing heel

The reconstruction of the distal third leg and weight-bearing heel, especially when complicated with infection and/or dead space, remains a challenge in reconstructive surgery. The distally based sural neurofasciomyocutaneous flap has been proved a valuable tool in repair of the soft tissue defects of those areas. In this report, we present the results of the anatomical study on vascular communication between the suprafascial sural neurovascular axis and the deep gastrocnemius muscle and a modified technique in clinical applications for reconstruction of the soft tissue defects in the distal lower leg and heel. Six lower limbs of fresh cadavers were injected with red gelatin and dissected. A constant vascular connection with average four musculo-fasciocutaneous perforators with diameter 0.2-0.5 mm was identified in the overlapping area between the suprafascial sural neurovascular axis and the deep gastrocnemius muscle. Based on these findings, a modified distally based sural neurofasciomyocutaneous flap including the distal gastrocnemius muscle component was designed and used for repairs of the soft tissue defects in the distal lower limb and plantar heel pad in six patients. The blood supplies of flaps comprised either the peroneal perforator and adipofascial pedicle or the peroneal perforator only. The average size of the fasciocutaneous flap was 51 cm(2), and the muscle component 17.7 cm(2). All flaps survived uneventfully. Our results suggest that this technical modification could provide wider range for applications of the distally based sural neurofasciomyocutaneous flap in repair of the soft tissue defects of the lower extremity and heel.

[Study on thermal decomposition of HMX energetic materials by in-situ FTIR spectroscopy]

In-situ FTIR spectroscopy is a rising and dynamic technique. This technique, which combines the advantages of investigation in-situ and accurate structure analysis by FTIR spectsoscopy, can detect the chemical change of materials in different temperature with real time and obtain the relationship between micromechanism of materials and temperature. In the present paper, thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) heated with 5 degrees C x min(-1) was investigated by in-situ FTIR spectroscopy. The results demonstrate that C-N bond cleavage and N-N bond cleavage of HMX occur at 205 degrees C. With increasing temperature, the rupture rate of C-N bond is faster than that of N-N bond, which verifies that the cleavage of C-N bond is the dominant rupture form. The augment in tension of HMX cyclic confirms that intramolecular cyclization occurs in breakage of HMX. Eight kinds of gaseous products such as CO2, N2O, CO, NO, HCHO, HONO, NO2 and HCN were determined. According to the structure change in condensed state and gaseous products, the decomposition mechanism was deduced that HCHO, N2O, HONO and HCN were released due to the cleavage of C-N bond, and NO2 was released due to the cleavage of N-N bond.

Acute mediastinitis resulting from an unsuspected fish bone--case report

Acute mediastinitis is a serious medical condition with a mortality rate from 30 to 40% or even higher. Early diagnosis with prompt and aggressive treatment is essential to prevent its rapid progression. Severe odynophagia and respiratory distress with positive neck or chest findings should raise suspicion of mediastinitis. We report a rare case of acute mediastinitis secondary to the unexpected migration of an impacted fish bone from the esophagus.

Guillain-Barré syndrome in northwestern China

We reviewed 100 patients with Guillan-Barré syndrome (GBS) from 1994 to 2000 from northwestern China. We examined clinical and electro-diagnostics features and compared them to patients from Europe, North America and northern China. Results indicated that among 100 patients with GBS, the demyelinating pattern was present in 51 patients, the axonal pattern in 25 patients, and 8 patients were inexcitable, 12 patients equivocal and 4 patients normal. The electrophysiological and clinical features of various subtypes of GBS in northwestern China seemed to be different in some ways from those in western countries and in northern China. However, in northwestern China, the demyelinating pattern is the major electrophysiological subtype.

Renin expression in COX-2-knockout mice on normal or low-salt diets

Experiments were performed in mice to investigate whether cyclooxygenase-2 (COX-2) in epithelial cells near the tubulovascular contact point (macula densa and TAL cells) may regulate renin gene expression in juxtaglomerular granular cells. Renin activity, afferent arteriolar granularity, and renin mRNA were determined in wild-type mice and in COX-2-knockout mice on control and low-NaCl diets. Renin activity in microdissected glomeruli assessed as angiotensin I formation in the presence of excess substrate and afferent arteriolar granularity determined by direct visualization and immunostaining were significantly reduced in COX-2 -/- compared with wild-type animals. Similarly, renal cortical mRNA levels were lower in COX-2 -/- than in wild-type mice. Maintaining mice on a low-salt diet for 14 days induced an increase in renin mRNA, afferent arteriolar granularity, and renin activity in wild-type mice. In contrast, renin mRNA and renin granularity did not significantly increase in low-salt-treated COX-2 -/- mice, whereas the increase in juxtaglomerular renin enzyme activity was markedly attenuated, but not fully blocked. In additional experiments we found that COX-2 mRNA was increased in angiotensin type 1A receptor-knockout mice compared with wild-type mice. We conclude that COX-2 in the tubulovascular contact region is a critical determinant of renin synthesis in granular cells under resting conditions and that it participates in the stimulation of renin expression caused by a low-NaCl intake.

Differential regulation of COX-2 expression in the kidney by lipopolysaccharide: role of CD14

Induction of the inducible cyclooxygenase isoform COX-2 is likely to be an important mechanism for increased prostaglandin production in renal inflammation. We examined the effect of lipopolysaccharide (LPS) on regional renal COX-2 expression in the rat. In the inner medulla, LPS injection (4 mg/kg ip) induced a twofold and 2.5-fold increase in the levels of COX-2 mRNA and COX-2 protein, respectively. In contrast, COX-2 expression in the renal cortex was not significantly altered. COX-2 promoter transgenic mice were created using the 2.7-kb flanking region of the rat COX-2 gene. In these animals, LPS injection induced reporter gene expression predominately in the inner medulla. The LPS receptor CD14, usually regarded as a monocyte/macrophage-specific marker, was found to be abundantly expressed in the inner medulla and in dissected inner medullary collecting duct (IMCD) cells, suggesting that it may mediate medullary COX-2 induction. CD14 was present only at low levels in cortex and cortical segments, including glomeruli. In cultured cells, it was abundant in mouse IMCD (mIMCD-K2) cells and renal medullary interstitial cells, but largely undetectable in mesangial cells and M1 cells, a cell line derived from mouse cortical collecting ducts. In the mIMCD-K2 cell line, LPS significantly induced COX-2 mRNA expression, with concomitant induction of CD14. LPS-stimulated COX-2 expression was reduced by the addition of an anti-CD14 monoclonal antibody to the culture medium. These results demonstrate that LPS selectively stimulates COX-2 expression in the renal inner medulla through a CD14-dependent mechanism.

Localization of PEPT1 and PEPT2 proton-coupled oligopeptide transporter mRNA and protein in rat kidney

To determine the renal localization of oligopeptide transporters, Northern blot analyses were performed and polyclonal antisera were generated against PEPT1 and PEPT2, the two cloned rat H+/peptide transporters. Under high-stringency conditions, a 3.0-kb mRNA transcript of rat PEPT1 was expressed primarily in superficial cortex, whereas a 3.5-kb mRNA transcript of PEPT2 was expressed primarily in deep cortex/outer stripe of outer medulla. PEPT1 antisera detected a specific band on immunoblots of renal and intestinal brush-border membrane vesicles (BBMV) with an apparent mobility of approximately 90 kDa. PEPT2 antisera detected a specific broad band of approximately 85 kDa in renal but not in intestinal BBMV. PEPT1 immunolocalization experiments showed detection of a brush border antigen in S1 segments of the proximal tubule and in the brush border of villi from all segments of the small intestine. In contrast, PEPT2 immunolocalization was primarily confined to the brush border of S3 segments of the proximal tubule. All other nephron segments in rat were negative for PEPT1 and PEPT2 staining. Overall, our results conclusively demonstrate that although PEPT1 is expressed in early regions of the proximal tubule (pars convoluta), PEPT2 is specific for the latter regions of proximal tubule (pars recta).

Tubuloglomerular feedback in ACE-deficient mice

In these experiments, we used a strain of angiotensin converting enzyme (ACE) germline null mutant mice, generated by J. H. Krege and co-workers (J. H. Krege, S. W. M. John, L. L. Langenbach, J. B. Hodgin, J. R. Hagaman, E. S. Bachman, J. C. Jennette, D. A. O'Brien, and O. Smithies. Nature 375: 146-148, 1995), to examine the effect of chronic ACE deficiency on the magnitude of tubuloglomerular feedback (TGF) responses. The genotype was determined by PCR on DNA extracted from the tail and was verified after each experiment by assessment of the blood pressure response to an injection of ANG I. To assess TGF responsiveness, we determined the change in stop-flow pressure (PSF) caused by increasing NaCl concentration at the macula densa by using micropuncture techniques. When loop of Henle flow rate was increased from 0 to 40 nl/min, PSF fell from a mean of 42.3 +/- 1.95 to 33.6 +/- 2.09 mmHg (n = 6, P = 0.005) in wild-type mice (+/+), fell from 40.6 +/- 2.35 to 38.6 +/- 1.93 mmHg in heterozygous (+/-) mice (n = 7, P = 0.014), and did not change in homozygous ACE (-/-) mice [36.7 +/- 2.02 mmHg vs. 36.4 +/- 2.01 mmHg; n = 4, P = not significant (NS)]. During an infusion of ANG II at a dose that did not significantly elevate blood pressure (70 ng. kg-1. min-1), TGF response magnitude (PSF 0 - PSF 40) increased from 6.5 +/- 1.4 to 9.8 +/- 1.19 mmHg in +/+ (P = 0.006), from 1.14 +/- 0.42 to 4.6 +/- 1.3 mmHg in +/- (P = 0.016), and from 0.42 +/- 0.25 to 4.02 +/- 1.06 in -/- mice (P = 0.05). Absence of TGF responses in ACE null mutant mice and restoration of near-normal responses during an acute infusion of ANG II supports previous conclusions that ANG II is an essential component in the signal transmission pathway that links the macula densa with the glomerular vascular pole.

Inhibition of adenosine-1 receptor-mediated preglomerular vasoconstriction in AT1A receptor-deficient mice

The effect of the adenosine type 1 receptor agonist N6-cyclohexyladenosine (CHA) on glomerular vascular reactivity was studied in male angiotensin II type 1A (AT1A) receptor knockout mice (9). Vascular reactivity was assessed as the response of stop-flow pressure (PSF) to infusion of CHA into loops of Henle using micropuncture techniques. In AT1A +/+ mice at ambient arterial blood pressure (96.7 +/- 2.8 mmHg), the presence of CHA (10 (-5) M) in the perfusate increased PSF responses from 6.8 +/- 0.6 to 14.3 +/- 0.9 mmHg when the loop of Henle of the index nephron was perfused and from 0.7 +/- 0.3 to 12.3 +/- 1.0 mmHg when the loop of an adjacent nephron was perfused. At reduced arterial blood pressure (82.8 +/- 1. 3 mmHg), index nephron perfusion with CHA increased PSF responses from 4.5 +/- 0.3 to 9.4 +/- 0.4 mmHg. In AT1A -/- mice with a mean arterial blood pressure of 80 +/- 1.9 mmHg, CHA increased PSF responses only from 0.1 +/- 0.3 to 3.6 +/- 0.54 mmHg during index nephron perfusion and from 0.25 +/- 0.2 to 2.7 +/- 0.55 mmHg during adjacent nephron perfusion, significantly less than in wild-type animals (P < 0.001). Responses to CHA were intermediate in AT1A +/- mice. Thus AT1A receptor knockout mice show a markedly reduced constrictor response to CHA both in the presence and absence of simultaneous activation of the tubuloglomerular feedback system. These data support the notion of a functional interaction between adenosine and angiotensin II in the regulation of afferent arteriolar tone.

Tubuloglomerular feedback: new concepts and developments

Luminal [NaCl] at the macula densa (MD) has two established effects: regulation of glomerular arteriolar resistance through tubuloglomerular feedback (TGF) and control of renin secretion. TGF acts as a minute-to-minute stabilizer of distal salt delivery, thereby minimizing the impact of random perturbations in filtration and absorption forces on NaCl excretion. During long-lasting perturbations of MD [NaCl], control of renin secretion becomes the dominant function of the MD. The potentially maladaptive effect of TGF under chronic conditions is prevented by TGF adaptations permitting adjustments in glomerular filtration rate to occur. TGF adaptation is mechanistically coupled to the endpoint targeted by chronic deviations in MD [NaCl], the rate of local and systemic angiotensin II generation. Studies of TGF in transgenic mice are expected to provide further insights into the mechanisms mediating between luminal [NaCl] and afferent arterioles. TGF responses are virtually abolished in mice in which either the AT1A gene or the angiotensin converting enzyme gene is rendered nonfunctional by homologous recombination. In contrast, TGF responses are unaltered in nitric oxide synthase I knockout mice. Thus, an intact renin-angiotensin system appears to be critical for the TGF signaling pathway.

Tubular localization and tissue distribution of peptide transporters in rat kidney

PURPOSE

To define the tubular localization and tissue distribution of PEPT1 (low-affinity, high-capacity transporter) and PEPT2 (high-affinity, low-capacity transporter) in rat kidney.

METHODS

mRNA expression of PEPT1 and PEPT2 was assessed with reverse transcription-polymerase chain reaction (RT-PCR) methods using cDNA prepared from microdissected nephron segments in rat. Tissue localization of rat renal PEPT1 and PEPT2 mRNA was further assessed by in situ hybridization with radiolabeled probes.

RESULTS

RT-PCR analysis of microdissected segments from rat nephron showed that both PEPT1 and PEPT2 are confined to a proximal tubule. While PEPT1 is specific for early regions of the proximal tubule (pars convoluta), PEPT2 is overwhelmingly but not exclusively expressed in latter regions of the proximal tubule (pars recta). All other segments along the nephron were negative for PEPT1 or PEPT2 mRNA transcripts. These finding were supported by in situ hybridization results in which PEPT1 was selectively expressed in kidney cortex and PEPT2 in the outer stripe of outer medulla.

CONCLUSIONS

Contrary to current opinion, the data suggest that peptides are handles in a sequential manner in proximal regions of the nephron, first by the low-affinity, high-capacity transport system and second by the high-affinity, low-capacity transport system.

Long-term results of percutaneous balloon mitral valvuloplasty for mitral stenosis: a follow-up study to 11 years in 202 patients

We studied the first 202 patients with rheumatic mitral stenosis (MS) who underwent percutaneous balloon mitral valvuloplasty (PBMV) with the Inoue balloon catheter for a follow-up (FU) period of 5-11 years. Pre- and post-PBMV and at FU, the mean left atrial pressure was 21.3+/-7.4, 10.2+/-5.6, and 11.2+/-4.1 mm Hg; mean diastolic mitral gradient was 18.4+/-7.3, 2.9+/-3.2, and 5.1+/-4.3 mm Hg; and mitral valve area was 1.0+/-0.3, 2.1+/-0.6, and 1.7+/-0.5 cm2. Functional status improved from New York Heart Association (NYHA) class IV in 3, class III in 119, and class II in 80 pre-PBMV to class I in 163, class II in 37, and class III in 2 post-PBMV, and was class I in 146, class II in 39, and class III in 17 patients at FU. In the 17 patients with NYHA class III at FU, mitral restenosis was the culprit; 4 underwent repeat PBMV, 12 had mitral valve replacement for severe mitral calcification and subvalvular fusion, and 1 refused further intervention. Thus PBMV using the Inoue balloon catheter is an effective method of relieving MS with excellent long-term results in patients without severe mitral calcification and subvalvular fusion.

Absence of tubuloglomerular feedback responses in AT1A receptor-deficient mice

Experiments were performed in a recently generated strain of mice with an angiotensin II AT1A-receptor null mutation (M. Ito, M. I. Oliverio, P. J. Mannon, C. F. Best, N. Maeda, O. Smithies, and T. M. coffman. Proc. Natl. Acad. Sci. USA 92: 3521-3525, 1995) to examine the effects of chronic AT1A receptor deficiency on tubuloglomerular feeback (TGF) responses. All animals were genotyped by polymerase chain reaction using primers designed to amplify sequences from the deleted AT1A gene and from the neomycin resistance gene. Normal mice (AT1A +/+) and mice heterozygous (AT1A +/-) and homozygous (AT1A -/-) for the gene disruption were anesthetized, and stop-flow pressures (PSF) were determined during changes in loop perfusion rate with previously established micropuncture methods. In five AT1A +/+ mice (26 tubules) mean PSF at zero loop flow was 37.2 +/- 1.5 mmHg, falling to 28.2 +/- 1.9 mmHg at a flow of 45 nl/min (P < 0.0001). Flow rate causing the half-maximum response (V1/2) was 8.7 +/- 0.4 nl/min. In four AT1A +/- animals (19 tubules) mean PSF at zero flow was 39.9 +/- 2.4 mmHg, falling to 34.8 +/- 2.7 mmHg at 45 nl/min (mean V1/2 8.6 +/- 1.04 nl/min). In five AT1A -/- mice (24 tubules) PSF was not significantly affected by loop flow with PSF averaging 33.9 +/- 1.7 mmHg at zero flow and 33.2 +/- 1.6 mmHg at 45 nl/min (not significant). Mean arterial blood pressures in the anesthetized and laparotomized mice were 91.8 +/- 2.2, 97.1 +/- 3, and 80.7 +/- 3.2 mmHg in the AT1A +/+, AT1A +/-, and AT1A -/- animals, respectively. Blood pressure responses to exogenous angiotensin II were greatly blunted in the AT1A -/- mice. We conclude that AT1A receptor-mediated effects of angiotensin II are in essential component of TGF responsiveness under chronic conditions. Our studies show the feasibility of using complex micropuncture methods in mice, an approach that widens the potential of genetically altered mouse strains as experimental models.

Expression of PTHrP, PTH/PTHrP receptor, and Ca(2+)-sensing receptor mRNAs along the rat nephron

To provide a frame of reference for studies of renal divalent cation and phosphate metabolism, we assessed the cellular localization of kidney calcium receptor (RaKCaR), parathyroid hormone-related protein (PTHrP), and parathyroid hormone/ parathyroid hormone-related protein (PTH/PTHrP) receptor mRNA. The studies used using reverse transcription-polymerase chain reaction (RT-PCR) applied to cDNA prepared from dissected rat nephron segments and from primary cultures of mouse juxtaglomerular granular cells. With species-specific primers, PCR products of expected size were obtained for RaKCaR (967 bp), PTHrP (420 bp), and PTH/PTHrP receptor (817 bp), with product identity being confirmed by restriction digestion. RaKCaR mRNA was found in medullary and cortical thick ascending limbs (MTAL and CTAL, respectively), the macula densa-containing segment, distal convoluted tubules (DCT), and, to a lesser extent, in cortical collecting ducts (CCD). It was not found in glomeruli, proximal convoluted and straight tubules (PCT and PST, respectively), outer and inner medullary collecting ducts (OMCD and IMCD, respectively), or in juxtaglomerular granular cell isolates. PTHrP mRNA was predominantly expressed in glomeruli and at lower levels in PCT and the macula densacontaining segment but was not detectable in CTAL, MTAL, DCT, and CD segments. Presence of PTH/PTHrP receptor mRNA was demonstrated in glomeruli, PCT, PST, CTAL, MTAL, and DCT but not in CD segments. These results suggest that the function of TAL and DCT cells, in addition to being affected by PTH, may be directly altered by extracellular divalent cations through RaKCaR and that PTHrP may act in the glomerulus and proximal tubule as an autocrine or paracrine regulator of hemodynamics and phosphate transport.

Regulation of endothelin production and secretion in cultured collecting duct cells by endogenous transforming growth factor-beta

Confluent cultures of two renal collecting duct cell lines (M-1 and mIMCD-K2 cells derived from cortical and inner medullary collecting ducts, respectively) express endothelin1 (ET1), transforming growth factor-beta (TGF beta; both TGF beta 1 and TGF beta 2), and both types of the TGF beta receptor. Experiments were performed to test whether endogenous TGF beta may be a paracrine modulator of ET1 expression in these cells. Treatment of M-1 and mIMCD-K2 cells with TGF beta 2 antisense oligodeoxynucleotides (ODN) significantly reduced ET1 messenger RNA (mRNA) and ET secretion (as well as TGF beta 2 mRNA) in a concentration-dependent manner, whereas control ODN were without significant effects. To produce ET inhibition, antisense ODN had to be present in the basolateral medium, whereas its sole presence in the apical medium was without effect. In addition, a pan-specific TGF beta antibody caused a significant reduction of ET1 mRNA expression and ET1 secretion. M-1 cells were found to express high levels of the mRNA for plasminogen activator of both tissue and urokinase types. Addition of the nonspecific serine protease inhibitor aprotinin (50 micrograms/ml) to the medium for 24 h significantly reduced the secretion of ET1. These results suggest that secretion of endogenous TGF beta, at least in part activated by the plasminogen/plasmin system, participates in the regulation of ET1 synthesis and secretion by collecting duct cell lines.

A study on carcinogenesis of endogenous nitrite and nitrosamine, and prevention of cancer

Cancer patients show a salivary NO2- density that is twice that of healthy individuals. This indicates that endogenous NO2- is correlated with the cancer. By applying a culture medium modified by vitamin B1 or KCIO3, we have found that many bacteria in the human body (especially the bowels) can nitrify NH4+ to NO2-. NO2- can be combined with a second amine to form nitrosamine which is a carcinogen. We fed mice using G+ coccus, which can lead to a precancerous lesion and mammary carcinoma, and proved that nitrification in vivo is carcinogenic. We have tested a method to prevent cancer in 7392 workers. Patients with a salivary density of NO2- over 10 ppm for 3 consecutive days and with light symptoms were our targets for preventive treatment using antibiotics and nitrosamine destroyers. The result shows that the average cancer incidence rate in the control group is 58.4% higher than in the experimental group over 9 years. The difference between the two groups is statistically significant (x2 = 8.5, p < 0.01). This is reliable evidence that preventive treatment is effective when based on the idea that endogenous NO2- and nitrosamine are the carcinogens.

Localization of bumetanide- and thiazide-sensitive Na-K-Cl cotransporters along the rat nephron

The present study was undertaken to investigate the mRNA localization of the two major kidney-specific Na-K-Cl transport proteins, the bumetanide-sensitive cotransporter (NKCC2 in rabbit and BSC1 in rat) and the thiazide-sensitive cotransporter (TSC). NKCC2 from rabbit and mouse has been shown to exist in three isoforms (designated A, B, and F) that differ only in a 96-bp region. The divergent region of each of the three NKCC2 isoforms was cloned from rat kidney by a polymerase chain reaction (PCR)-based strategy, and isoform-specific primers were chosen. RNA and cDNA were prepared from renal cortex and medulla and from microdissected nephron segments. Using reverse transcription (RT)-PCR, the B isoform was detected only in cortex and the F isoform only in medulla, whereas the A from was found in both. In dissected nephron segments, the B form was found exclusively in cortical thick ascending limb (CTAL) and macula densa-containing segment (MDCS), the F form only in medullary thick ascending limb (MTAL) and outer medullary collecting duct, and the A form in CTAL, MDCS, and MTAL. An additional isoform including both A and F exons was identified by direct sequencing of a 592-bp product from medulla. The AF product was found only in the medulla and was localized exclusively in MTAL. TSC mRNA was detected exclusively in the distal convoluted tubule. Differential nephron localization of NKCC2 isoforms suggests that Na-K-Cl cotransporters may differ in their transport characteristics to explain regulation of salt transport along the nephron.

A comparative study of early postoperative hypoxemia in infants, children, and adults undergoing elective plastic surgery

To determine the influence of age on postoperative hypoxemia, we studied postoperative hypoxemia in 1152 patients, from infants to adults, ASA physical status I, undergoing elective plastic surgery. Subjects were divided into four groups on the basis of age: Group 1, infants aged 1 yr or less (n = 108); Group 2, children aged 1-3 yr (n = 240); Group 3, children aged 3-14 yr (n = 482); and Group 4, adults aged 14-58 yr (n = 322). Arterial oxygen saturation (Spo2) levels were recorded while patients were breathing room air in the postanesthesia recovery room shortly after arrival (0 min), and 5, 10, 15, 20, 30, 40, 50, 60, 120, and 180 min thereafter. Younger patients showed lower Spo2 levels and a higher incidence of hypoxemia during the early postoperative period. The incidences of hypoxemia (Spo2 = 86%-90%) and severe hypoxemia (Spo2 < or = 85%) in the recovery room were 30.6% and 16.7%, respectively, in Group 1, 20.0% and 10.0% in Group 2, 14.1% and 3.3% in Group 3, and 7.8% and 0.6% in Group 4. Hypoxemia occurred most commonly within 1 h after anesthesia, particularly during the first 40 min in infants and during the first 15 min in older children and adults. A significant correlation was found by linear regression analysis between low Spo2 levels on admission to the recovery room and children's age. Thereafter, Spo2 levels and the incidence of hypoxemia during the early postoperative period were related only to infants' recovery scores.

Effect of transmembrane Ca2+ gradient on the coupling of beta-adrenergic receptors and adenylyl cyclase

In order to investigate the effect of transmembrane Ca2+ gradient on Gs mediated coupling of beta-AR and adenylyl cyclase, beta-AR from duck erythrocytes and Gs and adenylyl cyclase from bovine brain cortices were co-reconstituted into asolectin liposomes with different transmembrane Ca2+ gradient. These proteoliposomes were proven to be impermeable to water-soluble substances. The results obtained indicate that a physiological transmembrane Ca2+ gradient (1000-fold) is essential for higher stimulation of adenylyl cyclase by hormone-activated beta-AR via coupling to Gs and can be further enhanced by the decrease of such Ca2+ gradient within certain range (100 fold) following Ca2+ influx into cells during signal transduction. Fluorescence polarization of DPH revealed that transmembrane Ca2+ gradient modulates adenylyl cyclase and its stimulation by hormones through mediating a change in lipid fluidity. Correspondent conformational changes of beta-AR were also detected from the fluorescence spectra and quenching of Acrylodan-labelled beta-AR in those proteoliposomes. It is suggested that a proper transmembrane Ca2+ gradient is essential for the optimal fluidity of the phospholipid bilayer in the proteoliposomes, which favors the formation of a suitable conformation of the reconstituted beta-AR and thus promotes the stimulation of adenylyl cyclase activities by hormone-activated beta-AR via Gs.

Percutaneous balloon valvuloplasty for pulmonic stenosis in adolescents and adults

BACKGROUND

Percutaneous balloon valvuloplasty has been the accepted first-line treatment for congenital pulmonic stenosis in children. Its efficacy in adolescents and adults is less well defined.

METHODS

Between December 1985 and July 1995 we performed percutaneous pulmonic valvuloplasty with a single Inoue balloon catheter in 53 adolescent or adult patients 13 to 55 years of age (mean [+/- SD], 26 +/- 11). Follow-up studies were performed 0.2 to 9.8 years after the procedure (mean, 6.9 +/- 3.1) by Doppler echocardiography (in all the patients) and by cardiac catheterization and angiography (in nine patients).

RESULTS

After balloon valvuloplasty, the systolic pressure gradient across the pulmonic valve decreased from 91 +/- 46 mm Hg to 38 +/- 32 mm Hg (P < 0.001), and the diameter of the pulmonic-valve orifice increased from 8.9 +/- 3.6 mm to 17.4 +/- 4.6 mm (P < 0.001). In the nine patients catheterized at follow-up, the systolic gradient decreased from 107 +/- 48 mm Hg before valvuloplasty to 50 +/- 29 mm Hg after valvuloplasty and to 30 +/- 16 mm Hg at follow-up (P < 0.001 for the comparison of the gradient before and after valvuloplasty; P < 0.001 for the comparison before valvuloplasty and at follow-up; and P < 0.05 for the comparison after valvuloplasty and at follow-up). In the same nine patients, the diameter of the pulmonic valve, as measured by right ventricular angiography, increased from 8.3 +/- 1.4 mm before valvuloplasty to 17.2 +/- 2.0 mm after valvuloplasty (P < 0.001) and to 18.4 +/- 1.4 mm at follow-up (P = 0.08). Incompetence of the pulmonic valve was noted in 7 of the 53 patients (13 percent) after balloon valvuloplasty, but it had disappeared at follow-up in all of them.

CONCLUSIONS

Patients with congenital pulmonic stenosis who present in late adolescence or adult life can be treated with percutaneous balloon valvuloplasty with excellent short-term and long-term results that are similar to those in young children.

Observation of early postoperative hypoxaemia in children undergoing elective plastic surgery

The incidence, severity and duration of early postoperative hypoxaemia were determined in 420 healthy infants and children undergoing elective plastic surgery. Mean value of preoperative SpO2 was 98.3 +/- 0.87%. However, it decreased significantly to 92.7 +/- 4.01% immediately following anaesthesia in the postanaesthesia recovery room (PAR) when children breathed room air. Then SpO2 gradually increased to 93.8 +/- 4.25% at 10 min, 95.4 +/- 3.14% at 30 min, 96.6 +/- 2.25% at 60 min, 96.9 +/- 1.69% at 120 min, and 97.4 +/- 1.55% at 180 min, respectively. The incidence of hypoxaemia and severe hypoxaemia, which were 14.8% and 6.2% respectively on arrival in the PAR, decreased significantly to 6.6% and 1.9%, 30 min later. The hypoxaemia occurred most commonly within 1 h, particularly the first 30 min following anaesthesia. The hypoxaemia was more common and more severe in children undergoing cleft palate repair than other kinds of plastic surgery. A significant correlation was found between low SpO2 levels on admission to the PAR and children's age, fentanyl doses, and the infants' recovery score.

[Expression of the extracellular domain (1-341) of rat ovarian lutropin receptor in insect cells and preliminary characterization of the expressed product]

Extracellular domain residues 1-341 (designed R 341) of luteinizing hormone/human chorionic gonadotropin receptor (LH/hCG receptor) has high binding affinity for ligand. This paper describes expression of cDNA coding for R 341 in insect cells and preliminary identification of the expressed protein. SDS-PAGE silver staining and immunoblotting analysis show expressed product appears in two bands, major band has molecular weight 38.5 Kd, and weak band, 40.0 Kd. Ligand binding immunoblotting and 125I-hCG-binding blotting analysis indicate that expressed product R 341 has specific binding affinity for ligand. Ligand binding assay and Scatchard analysis indicate that recombinant receptor R 341 has high binding affinity for hCG and Kd is 5.68 x 10(-10) mol/L.

Transmembrane Ca2+ gradient and function of membrane proteins

This review will focus on the recent advance in the study of effect of transmembrane Ca2+ gradient on the function of membrane proteins. It consits of two parts: 1. Transmembrane Ca2+ gradient and sarcoplasmic reticulum Ca(2+)-ATPase; 2. Effect of transmembrane Ca2+ gradient on the components and coupling of cAMP signal transduction pathway. The results obtained indicate that a proper transmembrane Ca2+ gradient may play an important role in modulating the conformation and activity of SR Ca(2+)-ATPase and the function of membrane proteins involved in the cAMP signal transduction by mediating the physical state change of the membrane phospholipids.

Cardiovascular responses to graded doses of three catecholamines during lactic and hydrochloric acidosis in dogs

We have studied the cardiovascular effects of incremental doses of three catecholamines in dogs subjected to lactic (LAC) and hydrochloric (HCl) acidosis. Fifty-four dogs were allocated randomly to one of three groups: control, LAC and HCl acidosis (n = 18 each group). In the acidotic models, 2 mol litre-1 of lactic acid (4 ml kg-1 h-1) or 2 mol litre-1 of HCl (1 ml kg-1 h-1) was infused i.v. until arterial pH was reduced to 7.00 +/- 0.1. Within each group, six dogs received one of three different drugs in logarithmically incremental doses: adrenaline 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 micrograms kg-1 min-1, noradrenaline 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 micrograms kg-1 min-1 and dobutamine 5, 10, 20, 40, 80, 160 micrograms kg-1 min-1. Cardiovascular variables were monitored, with periodic measurements of plasma electrolyte and lactate concentrations. The pH reduction induced by HCl or lactic acid was associated with a statistically significant increase in mean pulmonary arterial pressure (MPAP), prominent especially in the LAC group where MPAP increased from mean 18 (SD 5) to 27 (6) mm Hg. In the acidotic models, the reduction in myocardial responsiveness to adrenaline or noradrenaline was more prominent than that for the control for corresponding doses of drugs. In the LAC group mean cardiac index decreased significantly from 5.2 (1.8) to 2.2 (0.7) litre min-1 m-2 after infusion of adrenaline 3.2 micrograms kg-1 min-1 and decreased from 5.1 (1.1 to 2.4 (0.9) litre min-1 m-2 after infusion of noradrenaline 3.2 micrograms kg-1 min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of transmembrane Ca2+ gradient on Gs function

Gs and adenylate cyclase from bovine brain cortices were co-reconstituted into asolectin liposomes with or without 1000-fold transmembrane Ca2+ gradient. Obtained results showed that Gs activities of both binding GTP gamma S and stimulating adenylate cyclase were the highest in proteoliposomes, with a transmembrane Ca2+ gradient similar to the physiological situation and the lowest while the transmembrane Ca2+ gradient was in the inverse direction. Such a difference could be diminished following the dissipation of the transmembrane Ca2+ gradient by A23187. Time-resolved fluorescence anisotropy of diphenylhexatriene (DPH) has been used to compare the physical state of phospholipids among those proteoliposomes. It is suggested that a proper transmembrane Ca2+ gradient is essential for higher membrane fluidity, which may favor Gs function with higher GTP-binding activity and stimulation of adenylate cyclase.

Divalent cation and lipid-protein interactions of biomembranes

Divalent cations play an important role in the functions of biomembranes. This review deals with three topics: (1) Mg(2+)-mediated change in physical state of phospholipid induces conformation and activity change of reconstituted mitochondrial H(+)-ATPase, (2) a proper transmembrane Ca2+ gradient is essential for the higher enzymatic activity of adenylate cyclase, and (3) role of transmembrane Ca2+ gradient in the modulation of reconstituted sarcoplasmic reticulum Ca(2+)-ATPase activity.