Bcl-xL promotes the open configuration of the voltage-dependent anion channel and metabolite passage through the outer mitochondrial membrane

The diffusion of metabolites across the outer mitochondrial membrane is essential for coupled cellular respiration. The outer membrane of mitochondria isolated from growth factor-deprived cells is impaired in its ability to exchange metabolic anions. When added to mitochondria, recombinant Bcl-x(L) restores metabolite exchange across the outer membrane without inducing the loss of cytochrome c from the intermembrane space. Restoration of outer membrane permeability to anionic metabolites does not occur directly through Bcl-x(L) ion channels. Instead, recombinant Bcl-x(L) maintains the outer mitochondrial membrane channel, VDAC, in an open configuration. Consistent with these findings, when ADP-induced oxidative phosphorylation is limited by exogenous beta-NADH, recombinant Bcl-x(L) can sustain outer mitochondrial membrane permeability to ADP. beta-NADH limits respiration by promoting the closed configuration of VDAC. Together these results demonstrate that following an apoptotic signal, Bcl-x(L) can maintain metabolite exchange across the outer mitochondrial membrane by inhibiting VDAC closure.

D1 dopamine receptor regulation of NHE3 during development in spontaneously hypertensive rats

To determine if the defective interactions among D1-like receptors, G proteins, and Na+/H+ exchanger 3 (NHE3) are consequences of hypertension, we studied these interactions in rats, before (2–3 wk) and after (12 wk) the establishment of hypertension. To eliminate the confounding influence of second messenger action on D1 receptor-NHE3 interaction, studies were performed in renal brush-border membranes (BBM) devoid of cytoplasmic second messengers. NHE3 activity increased with age in Wistar-Kyoto (WKY) rats (3 wk = 1.48 ± 0.39, n = 13; 12 wk = 2.83 ± 0.15, n = 16, P < 0.05) but not in spontaneously hypertensive rats (SHRs; 3 wk = 2.52 ± 0.37, n = 11; 12 wk = 2.81 ± 0.20, n = 16). D1 receptor protein tended to decrease, whereas NHE3 protein tended to increase with age in both WKY and SHRs. However, the inhibitory effect of a D1-like agonist, SKF-81297, on NHE3 activity increased with age in WKY rats (3 wk = −40.7 ± 5.3%, n = 10, 12 wk = −58.7 ± 4.6%, n = 12, P < 0.05) but not in SHRs (3 wk = −27.6 ± 5.9%, n = 11, 12 wk = −25.1 ± 3.2%, n = 11). The decreased inhibitory effect of another D1-like agonist, fenoldopam, on NHE3 activity in SHRs was not caused by increased activity and binding of Gβγ to NHE3 as has been reported in young WKY rats. Gsα mediates, in part, the inhibitory effect of D1-like agonists on NHE3 activity. In WKY rats, fenoldopam increased Gsα/NHE3 binding to the same extent in 2-wk-old (1.5-fold, n = 4) and adult (1.5-fold, n = 4) rats. In contrast, in SHRs, fenoldopam decreased the amount of Gsα bound to NHE3 in 2-wk-old SHRs and had no effect in 4-wk-old and adult SHRs. These studies indicate that the decreased inhibitory effect of D1-like agonists on NHE3 activity in SHRs (compared with WKY rats) precedes the development of hypertension. This may be caused, in part, by a decreased interaction between Gsα and NHE3 in BBM secondary to impaired D1-like receptor function.

[Clinical effects of revascularization in lower limb ischemia]

OBJECTIVE

To investigate the clinical effects of revascularization in lower extremity for severe ischemia.

METHODS

Fifty-six lower limbs with severe ischemia in 49 patients were evaluated retrospectively, who underwent surgical intervention from January of 1995 to December of 2000. By arteriography, the actual anatomic distributions of occlusive disease included infrarenal aorta-bicommon iliac arteries, abdominal aorta-bicommon iliac arteries, iliac artery, and femoral artery or femoropopliteal artery. The indication for surgery was disabling claudication, rest pain and gangrene. Fourteen limbs in 12 cases received arterialization of femoral venous system by artificial venous-arterial fistula. Artificial vascular grafts were implanted in 33 limbs of 28 cases, endarterectomy and patch profundaplasty were performed in 5 limbs of 5 cases, and primary amputation was carried out in 4 cases.

RESULTS

During 38 months follow-up in average, 4 limbs were amputated within 52 revascularizated limbs, and accumulated amputation rate was 14.3%. Patency rate was 68.4% in arterial revascularization limbs (26/38 limbs), and limb survival rate was 94.7%(36/38 limbs) by procedure of artificial vascular grafts, endarterectomy and patch profundaplasty. Limb survival rate in procedure of artificial venous-arterial fistula was 85.7%(12/14 limbs).

CONCLUSION

In treatment of severe lower extremity ischemia, the effective revascularization can be achieved by artificial vascular bypass, endarterectomy and patch profundaplasty, or arterialization of femoral venous system. Options in the surgical management should depend on individual. Arteriography is essential for revascularization and properly planning a practicable surgical approach.

Adenosine enhances glial glutamate efflux via A2a adenosine receptors

The present study investigated the effect of adenosine on glial glutamate efflux. Adenosine (from 1 nM to 100 microM) enhanced the release from cultured rat glial cells in a bell-shaped dose-responsive manner for the hippocampus and in a dose-dependent manner for the superior colliculus, and a similar increase was obtained with the A2a adenosine receptor agonist, 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS21680), but not with the A1 adenosine receptor agonist, N6-cyclohexyladenosine (CHA). Adenosine and CGS21680 also enhanced glutamate efflux from Xenopus oocytes injected with the poly (A)+ mRNAs derived from cultured glial cells for the hippocampus and the superior colliculus together with and without the A2a adenosine receptor mRNA, but instead such increase was not found in oocytes expressing A2a adenosine receptors alone. The results of the present study thus suggest that adenosine enhances glutamate efflux from glial cells via A2a adenosine receptors, and this may represent a mechanism underlying the facilitatory action of adenosine on hippocampal and superior colliculus neurotransmissions.

Dopamine(1) receptor, G(salpha), and Na(+)-H(+) exchanger interactions in the kidney in hypertension

The ability of dopamine(1) (D(1)) receptors to inhibit luminal Na(+)-H(+) exchanger (NHE) activity in renal proximal tubules and induce a natriuresis is impaired in spontaneously hypertensive rats (SHR). However, it is not clear whether the defect is at the level of the D(1) receptor, G(salpha), or effector proteins. The coupling of the D(1) receptor to G(salpha) and NHE3 was studied in renal brush border membranes (BBM), devoid of cytoplasmic second messengers. D(1) receptor, G(salpha), and NHE3 expressions were similar in SHR and their normotensive controls, Wistar-Kyoto rats (WKY). Guanosine-5'-O:-(3-thiotriphosphate) (GTPgammaS) decreased NHE activity and increased NHE3 linked with G(salpha) similarly in WKY and SHR, indicating normal G(salpha) and NHE3 regulation in SHR. However, D(1) agonists increased NHE3 linked with G(salpha) in WKY but not in SHR, and the inhibitory effects of D(1) agonists on NHE activity were less in SHR than in WKY. Moreover, GTPgammaS enhanced the inhibitory effect of D(1) agonist on NHE activity in WKY but not in SHR, suggesting an uncoupling of the D(1) receptor from G(salpha)/NHE3 in SHR. Similar results were obtained with the use of immortalized renal proximal tubule cells from WKY and SHR. We conclude that the defective D(1) receptor function in renal proximal tubules in SHR is proximal to G(salpha)/effectors and presumably at the receptor level. The mechanism(s) responsible for the uncoupling of the D(1) receptor from G proteins remains to be determined. Because the primary structure of the D(1) receptor is not different between normotensive and hypertensive rats, differences in D(1) receptor posttranslational modification are possible.

Outer mitochondrial membrane permeability can regulate coupled respiration and cell survival

Coupled cellular respiration requires that ATP and ADP be efficiently exchanged between the cytosol and the mitochondrial matrix. When growth factors are withdrawn from dependent cells, metabolism is disrupted by a defect in ATP/ADP exchange across the mitochondrial membranes. Unexpectedly, we find that this defect results from loss of outer mitochondrial membrane permeability to metabolic anions. This decrease in anion permeability correlates with the changes in conductance properties that accompany closure of the voltage-dependent anion channel (also known as mitochondrial porin). Loss of outer membrane permeability (i) results in the accumulation of stored metabolic energy within the intermembrane space in the form of creatine phosphate, (ii) is prevented by the outer mitochondrial membrane proteins Bcl-x(L) and Bcl-2, and (iii) can be reversed by growth factor readdition. If outer membrane impermeability persists, the disruption of mitochondrial homeostasis culminates in loss of outer mitochondrial membrane integrity, cytochrome c redistribution, and apoptosis. The recognition that outer membrane permeability is regulated under physiological conditions has important implications for the understanding of bioenergetics and cell survival.

Gbeta regulation of Na/H exchanger-3 activity in rat renal proximal tubules during development

The decreased natriuretic action of dopamine in the young has been attributed to decreased generation of cAMP by the activated renal D(1)-like receptor. However, sodium/hydrogen exchanger (NHE) 3 activity in renal brush-border membrane vesicles (BBMV) can be modulated independent of cytoplasmic second messengers. We therefore studied D(1)-like receptor regulation of NHE activity in BBMVs in 2-, 4-, and 12-wk-old (adult) rats. Basal NHE activity was least in 2-wk-old compared with 4- and 12-wk-old rats. D(1)-like agonist (SKF-81297) inhibition of NHE activity was also least in 2-wk-old (-1 +/- 9%, n = 3) compared with 4 (-15 +/- 5%, n = 6)- and 12 (-65 +/- 4%, n = 6)-wk-old rats. The decreased response to the D(1)-like agonist in BBMV was not caused by decreased D(1) receptors or NHE3 expression in the young. G(s)alpha, which inhibits NHE3 activity by itself, coimmunoprecipitated with NHE3 to the same extent in 2-wk-old and adult rats. G(s)alpha function was also not impaired in the young because guanosine 5'-O-(3-thiotriphosphate) decreased NHE activity to a similar extent in 4-wk-old and adult rats. Galpha(i-3) protein expression in BBMV also did not change with age. In contrast, Gbeta expression and the amount of Gbeta that coimmunoprecipitated with NHE3 in BBMV was greatest in 2-wk-old rats and decreased with age. Gbeta common antibodies did not affect D(1)-like agonist inhibition of NHE activity in adult rats (8%) but markedly increased it (48%)in 4-wk-old rats. We conclude that the decreased inhibitory effect of D(1)-like receptors on NHE activity in BBMV in young rats is caused, in part, by the increased expression and activity of the G protein subunit Gbeta/gamma. The direct regulation of NHE activity by G protein subunits may be an important step in the maturation of renal tubular ion transport.

MR evaluation of subscapularis tears

PURPOSE

The purpose of this work was to describe the MR appearance of tears of the subscapularis tendon and compare the usefulness of different imaging planes as well as note the association of subscapularis tears with other rotator cuff tears and biceps tendon dislocations.

METHOD

MR studies at 1.5 T over an 8 year interval were retrospectively assessed for the presence of a rotator cuff tear and/or tear of the subscapularis tendon. Images that showed a subscapularis tear were reviewed for the presence of a visible tear separately on the axial, coronal, and sagittal images. The MR studies were also evaluated for associated tears of the supraspinatus, infraspinatus, and teres minor muscles as well as biceps tendon dislocation and the "naked humerus sign" on coronal images. Last, clinical records and surgical reports were reviewed.

RESULTS

Forty-five (2%) of 2,167 rotator cuff tears involved the subscapularis; 27% were partial and 73% were complete tears. Tears were best seen in the sagittal oblique plane. Almost all subscapularis tears were an extension of typical rotator cuff tears: supraspinatus in 35 patients (79%), extending into infraspinatus tears in 25 (56%) and into teres minor tears in 2 patients (4%). Bicipital dislocations were seen in 22 patients (49%), and three complete tears of the biceps (7%) were noted as well. The naked humerus sign was demonstrated in 31 patients (69%). Surgical reports that confirmed the MR findings were available for 15 patients.

CONCLUSION

About 2% of rotator cuff tears involve the subscapularis tendon. Most subscapularis tears are extensions of supraspinatus tears and frequently involve the biceps tendon.

Frequency and spectrum of abnormalities in the bone marrow of the wrist: MR imaging findings

OBJECTIVE

To describe the frequency of marrow abnormalities on wrist MR imaging and the MR findings of these various abnormalities.

DESIGN AND PATIENTS

Five hundred and nineteen patients were studied at 1.5 T. Two observers recorded the presence and location of avascular necrosis, occult fractures and arthritic edema [focal osteoarthritis, ulnolunate abutment, rheumatoid arthritis, septic arthritis, gouty arthritis and scapholunate advanced collapse (SLAC)].

RESULTS AND CONCLUSION

One hundred and eighty-seven (36%) patients demonstrated marrow abnormalities in the wrist, of which 101 were diagnosed as arthritis [64 (34%) as focal osteoarthritis, 17 (9%) as ulnolunate abutment, 15 (8%) as rheumatoid arthritis, 2 as septic arthritis, 2 as SLAC, and 1 as gouty arthritis]. Seventy-two patients had occult fractures and in 27 patients avascular necrosis was seen. MR imaging can reveal various abnormalities in bone marrow of the wrist when findings on radiography are normal or equivocal.

Dopamine D1 receptor and protein kinase C isoforms in spontaneously hypertensive rats

-Dopamine, via D1-like receptors, stimulates the activity of both protein kinase A (PKA) and protein kinase C (PKC), which results in inhibition of renal sodium transport. Since D1-like receptors differentially regulate sodium transport in normotensive and hypertensive rats, they may also differentially regulate PKC expression in these rat strains. Thus, 2 different D1-like agonists (fenoldopam or SKF 38393) were infused into the renal artery of anesthetized normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) (n=5 to 6/drug/strain). Ten or 60 minutes after starting the D1-like agonist infusion, both the infused kidney and the noninfused kidney that served as control were prepared for analysis. The D1-like agonists produced a greater diuresis and natriuresis and inhibited Na+,K+-ATPase activity in proximal tubule (PT) and medullary thick ascending limb (mTAL) to a greater extent in WKY (Delta20+/-1%) than in SHR (Delta7+/-1%, P<0.001). D1-like agonists had no effect on PKC-alpha or PKC-lambda expression in either membrane or cytosol but increased PKC-theta expression in PT in both WKY and SHR at 10 minutes but not at 60 minutes. However, membranous PKC-delta expression in PT and mTAL decreased in WKY but increased in SHR with either 10 or 60 minutes of D1-like agonist infusion. D1-like agonists also decreased membranous PKC-zeta expression in PT and mTAL in WKY but increased it in PT but not in mTAL in SHR. We conclude that there is differential regulation of PKC isoform expression by D1-like agonists that inhibits membranous PKC-delta and PKC-zeta in WKY but stimulates them in SHR; this effect in SHR is similar to the stimulatory effect of norepinephrine and angiotensin II and may be a mechanism for their differential effects on sodium transport.

Food intake patterns in urban Beijing Chinese

This study investigated the food consumption patterns of 430 Beijing Chinese adults and assessed the impact on these patterns of the following socio-demographic characteristics: gender, age, educational achievement, and gross household income. Food intake by category, food variety and meal patterns were assessed using a 156-item food frequency questionnaire. It was found that gender and age were the most important factors to influence food consumption patterns. Men consumed more wheat products, red meat and tea, whereas women consumed more vegetables, fruit, nuts, fish, eggs and milk. Women also tended to consume a wider variety of food than did men. Furthermore, it was found that younger and more educated people tended to consume a wider variety of food. Age also had an important influence on the food intake. Younger and generally more educated adults tended to consume foods associated with affluence: meats, soft drinks and beer, while the older population tended to consume more vegetables (women only), milk and tea in their diets. Because education is closely correlated with age in this Beijing Chinese population, it appeared to have little effect on the food intake patterns, after adjusting for age. The older members of this population, who probably have a decreased functional reserve of nutrients, and the less educated, appeared not to be taking advantage of the availability of a wide variety of food, further increasing the risk of nutrient deficiency. On the other hand, the younger and more educated, who tended to consume a wide variety of foods, were more likely to maintain adequate nutritional standards. However, their tendency to consume food associated with affluence, such as meat and beer, may point toward an increased risk of those diseases prevalent in affluent societies, such as obesity, diabeties, cardiovascular disease, certain cancers and osteoporosis. Ongoing nutrition surveillance and appropriate nutrition education will be required increasingly for Beijing Chinese and similar communities.

Combined intramuscular-intradermal protocol of universal neonate HB vaccination irrespective of mother's status of HBsAg

To evaluate a protocol of combined intramuscular-intradermal (i.m.-i.d.) universal hepatitis B (HB) vaccination of neonates regardless of the mothers' HB surface antigen HBsAg status, 160 full-term newborn babies were sequentially divided into groups A and B (test and control groups). The group A babies were immunized by giving 30 micrograms HB vaccine i.m. within 24 h after birth and 2 micrograms i.d. twice at 1 and 6 months of age. Group B babies were immunized by giving one initial dose of 30 micrograms i.m. and two booster doses of 10 micrograms i.m. after same 0, 1, 6-month schedule. Blood samples were collected at birth before the first dose of the HB vaccine, at 6 months of age before the third dose and at 12 months. The blood samples were tested for HBsAg and anti-HBs by using Abbott RIA reagents. All of the 160 newborns received three doses of vaccine, but in only 96 of them was the blood examination completed. The positive rate of anti-HBs > 10 IU l-1 was 76.27 and 83.08% in groups A and B, respectively at 6 months, and 83.72 and 92.45%, respectively at 12 months. The geometric mean titres (GMT) of anti-HBs was 42.25 and 60.25 IU l-1 in groups A and B, respectively at 6 months, and 74.45 and 87.1 IU l-1, respectively at 12 months. HBsAg was negative in the two groups 6 and 12 months after birth. The chi 2 and t-tests showed there were no significant differences in these data between the two groups. Thus was it demonstrated that the combined i.m.-i.d. protocol using 34 micrograms of HB vaccine can produce a protection similar to that of the conventional 50 micrograms i.m. regimen, while ca on-third of the vaccine can be saved. The new protocol is theoretically rational and may be ideal according to the cost-effectiveness principle.

Effects of thiofedrine on platelet aggregation, thromboxane B2 and 6-keto-PGF1 alpha in rats

Thiofedrine inhibited rat platelet aggregation and intraplatelet thromboxane B2 (TxB2) generation induced by arachidonic acid. The IC50 values were 0.18 and 0.21 mmol/l, respectively. Thiofedrine, 1.25-5.00 mg/kg i.v., showed a significant inhibition of rat platelet aggregation and intraplatelet TxB2 generation induced by arachidonic acid, with ID50 values of 2.4 and 3.3 mg/kg. Thiofedrine, 0.5-2.0 mg/kg i.v., reduced TxB2 generation but increased 6-keto-PGF1 alpha formation in rat plasma.

Eicosanoid production in rabbit tracheal epithelium by adenine nucleotides: mediation by P2-purinoceptors

Adenosine triphosphate (ATP) acting through epithelial nucleotide receptors exerts multiple physiologic actions on airway mucociliary clearance and caliber. However, the effect of ATP on arachidonate metabolism in the airway remains unknown. In this study, the ability of ATP to regulate eicosanoid production was studied in vitro in full-thickness rabbit tracheal strips and separately in rabbit epithelial explant cultures. In the freshly isolated strips, ATP increased prostaglandin E2 (PGE2) release in a dose-dependent fashion, with an activation threshold at 10 microM ATP and a 3.5-fold increase in PGE2 output at 1 mM ATP. Epithelium removal decreased 1 mM ATP-evoked PGE2 release by 68%. Reverse-phase, high-pressure liquid chromatography (HPLC) of media from 3H-arachidonic acid-incubated epithelial explants exposed to 1 mM ATP demonstrated increased output of the cyclooxygenase products PGE2 and prostaglandin F2a (PGF2a). Other identifiable eicosanoids did not increase. The concentration-response for ATP-induced PGE2 release by explants was similar to that of tracheal strips. PGE2 release by 1 mM ATP was 27% of that elicited by ionomycin (10 microM) and was markedly inhibited by indomethacin (10 microM). Purinoceptor agonist-stimulated PGE2 release by the epithelium yielded a rank order of potency of uridine triphosphate (UTP) > or = ATP > 2-methylthio-ATP (2MeSATP) >> alpha,beta-methyleneadenosine-5'-triphosphate (AMP-CPP) > or = adenosine. These results indicate that ATP, acting primarily through an epithelial P2-purinoceptor similar to the P2a subtype, stimulates eicosanoid metabolism in rabbit airway epithelium via the cyclooxygenase pathway, producing PGE2 as the predominant species.

Experimental study of chuanxiong on cerebrovascular hemodynamic parameters

In the experimental rabbit arteriosclerosis, the change of the cerebrovascular hemodynamic parameters (CVHP) and the effect of Chuanxiong (CX) on CVHP were observed. In arteriosclerosis group (AS group), the mean flow (Qmean), mean velocity (Vmean), maximal velocity (Vmax) and minimal velocity (Vmin) of the carotid blood flow and cerebrovascular compliance for zero pressure (CO) were significantly decreased (P < 0.05, 0.01), but the values of cerebrovascular peripheral resistance (R) and characteristic impedance (Zc) were significantly increased (P < 0.05 and 0.01), and the value of R showed significant positive correlation with the extent of carotid lesions (P < 0.01). All indexes of CVHP of the Chuanxiong group (CX group) were close to and had no significant difference from those of the normal group (N group) but Qmean, Vmean, Vmin, CO and R were significantly better than those of the AS group (P < 0.05, 0.01). These results showed that CX can effectively improve cerebrovascular hemodynamics.

[A study on risk factors of retinopathy of prematurity]

Ocular fundi of 54 premature infants (age of gestation < 37 weeks) and 5 full-term babies with low body weight (< 2500 g) were examined at the forth week after birth. According to the international classification of retinopathy of prematurity, they were diagnosed as retinopathy of prematurity (ROP). The risk factors of the incidence of ROP were statistically analyzed, respectively. The results show that the lower the body weight, the shorter the gestation, the higher the oxygen concentration, the longer the oxygen administration, the higher the incidence of ROP. The incidences of ROP in the following baby groups, the body weight at birth < or = 1500 g, gestational weeks < or = 32 weeks, the oxygen concentration administered > 80%, and the duration of persistent oxygen administration > 5 days are significantly higher than those in the corresponding respective other groups. It is also demonstrated that the duration of the first time of oxygen administration and the complications of the newborn babies such as asphyxia, intracranial hemorrhage, anemia, pneumonia and blood transfusion have no effects on the incidence of ROP.

[Primary pericardial mesothelioma: a clinicopathological analysis of 7 cases]

Primary pericardial mesotheliona is a clinical rarity. 7 cases were reported in this paper. There were no typical clinical symptoms and signs. It could not be diagnosed simply with chest film, ECG or echocardiagram and was usually misdiagnosed as constritive pericarditis, tuberculous pericarditis etc. In order to make correct diagnosis, some investigative diagnose methods such as pathological examination of pericardial fluid and pericardial biopsy, Gallium-67 scintigraphy, Ber-EP4 antibody and immunohistochemical procedures should be employed.

Influence of thiofedrine on platelet aggregation, intraplatelet cyclic cAMP and malondialdehyde in rats

Platelet aggregation and cyclic adenosine monophosphate (cAMP) production were studied by turbidimetry and competitive protein binding assay, respectively, in rats. Thiofedrine (Thi) significantly inhibited adenosine diphosphate (ADP)-induced and thrombin-induced platelet aggregation in vitro, with IC50 values of 0.56 and 0.16 mmol/l, respectively. In vivo, Thi 1.25-5.0 mg/kg i.v. significantly inhibited ADP-induced platelet aggregation at rate of 17.1-40.3%. Thi caused a dose-dependent increase in cAMP levels in rat washed platelets. Malondialdehyde (MDA) levels in rat platelets were measured by colorimetry. Thi had an inhibitory effect on thrombin-induced platelet MDA production. The results suggest that the antiaggregatory action of Thi may be related to metabolism of arachidonic acid (AA) and elevation of cAMP levels.

Two upstream cysteines and the CAAX motif but not the polybasic domain are required for membrane association of Xlcaax in Xenopus oocytes

We have analyzed the role of several protein motifs in controlling the membrane association of the xlcaax-1 protein in Xenopus oocytes. Xlcaax-1 is a maternally expressed protein that during development is associated with the basal lateral membrane of polarized epithelial cells. It is enriched in the tubule cells of the adult kidney and several other organs that are involved in osmoregulation. Xlcaax-1 has a C-terminal CAAX sequence (CVVM) identical to that of N-ras, followed by two cysteines that are potential palmitoylation sites and a polybasic domain. Mutants were constructed that either deleted specific domains or changed specific amino acids of the consensus sequences in or near the CAAX motif. Synthetic mRNAs were injected into Xenopus oocytes and their protein products analyzed for their ability to associate with the oocyte plasma membrane. A mutation changing cysteine-588 of the CAAX box to serine or the inhibition of prenylation by lovastatin eliminated the membrane association of the protein. Mutation of either of the upstream cysteines (either 585 or 587) also inhibited the association of xlcaax-1 with the membrane. Unlike Ras, however, deletion of the polybasic domain had no effect on membrane binding. In addition, we show that xlcaax-1 binds ATP but not GTP.

[Effects of oxyfedrine on high blood viscosity and myocardial necrosis induced by epinephrine and ice water stress in rats]

Acute high blood viscosity (HBV) and myocardial necrosis was established by epinephrine (Epi) and ice water stress in rats. Effects of iv oxyfedrine (Oxy) on HBV, plasma viscosity (PV), hematocrit, erythrocyte electrophoretic time (EET), and fibrinogenic viscosity (FV) were studied in model. Results showed that Oxy 1 mg.kg-1 iv markedly decreased the arterial and venous blood HBV at shear rates of 700 s-1 and 70 s-1, respectively (P < 0.01). There were significant differences in the alleviation of HBV among 3 groups (Oxy 0.01, 0.1, and 1 mg.kg-1 iv). The above doses markedly decreased the HBV, PV, and FV, and shortened the EET. Effects of iv Oxy on the myocardial necrosis rat model were scrutinized under the light and electron microscopes. Oxy iv 1 mg.kg-1.d-1 x 1, 3, and 5 d prevented or mitigated the occurrence and development of myocardial necrosis. The structure of heart mitochondria and myofibrils were clearly discernible. This action may be related to the alleviation of HBV by Oxy.

[Observations on vitrectomy with silicone oil injection]

Silicone oils were injected in 37 eyes of 37 patients among 95 patients performed vitrectomy during 1988-1990. The indication was complicated retinal detachment except for 2 cases of diabetic proliferative retinopathy and vitreous hemorrhage. In 29 (78.4%) of the 37 eyes, the retina was totally reattached, and in 7 eyes partially reattached that did not regain ambulatory vision. In 22.7% of the eyes successfully operated, cataracts developed with silicone oil 1,000mPa.s while transient hypertension occurred in 27.3% with silicone oil 5,000mPa.s. Vitrectomy with silicone oil filling may help some retinal detachments that are refractory to conventional retinal and vitreous operations; however, due to possible complications, the use of silicone oil should be in limited cases and removed after retinal reattachment.

Dose-dependent effects of 6-hydroxy dopamine on deprivation myopia, electroretinograms, and dopaminergic amacrine cells in chickens

We found that a single intravitreal injection of 6-hydroxy dopamine (6-OHDA) is highly efficient in blocking the development of deprivation-induced myopia in young chickens. To investigate the effects of 6-OHDA on retinal function, we studied electroretinograms (ERGs) in chickens aged 15-25 days, 4 days subsequent to the injection. Both spectral sensitivity and oscillatory potentials were tested. In addition, a histological examination was performed of dopaminergic amacrine cells labeled by a monoclonal antibody against tyrosine hydroxylase. We found that, at doses of 6-OHDA sufficient to suppress deprivation myopia entirely, no effect could be detected on either the ERGs or on the density and appearance of dopaminergic amacrine cells. For higher doses, spectral sensitivity and the number of dopaminergic amacrine cells declined gradually. In contrast, as doses increased, oscillatory potentials 1 and 2 grew in amplitude only to decline at the highest doses. The results indicate that (1) development of deprivation myopia requires normal retinal function and that (2) slight changes in the gains of dopaminergic pathways are sufficient to block the development of deprivation myopia.

[Evaluation of serum SC6 antigen using immunoradiometric assay for diagnosis of pancreatic cancer]

A solid-phase immunoradiometric sandwich assay for SC6 antigen was defined by a monoclonal antibody (SC6). The concentration of SC6 antigen in samples was determined by reference to a standard curve. The average intra- and interassay CV were 5.4% and 8.7% respectively. This antibody was found at low concentration in serum from 33 healthy individuals and the cutoff of normal upper limit of SC6 antigen was 41 U/ml. The level of serum SC6 antigen was assayed in 41 patients with pancreatic cancer, 95 with non-pancreatic carcinomas, and 48 with nonmalignant diseases. Frequency of elevated SC6 antigen level was highest in patients with gastrointestinal cancer, especially pancreatic cancer. The sensitivity and specificity were 70.7% and 84.3% for pancreatic cancer. The level in most cases of benign diseases was within upper normal limit. The results show that detection of SC6 antigen is valuable in the diagnosis of pancreatic cancer. It may be of help for detecting pancreatic cancer in its early stage.

The nuclear-cytoplasmic distribution of the Xenopus nuclear factor, xnf7, coincides with its state of phosphorylation during early development

We describe the characterization in Xenopus laevis of a nuclear protein, xnf7, which is first detected in the oocyte GV and is eventually enriched in nuclei of cells of the adult brain. Previous studies have shown that this protein contains zinc-finger-like structures and acidic domains typical of transcriptional activators, and is phosphorylated in vitro by p34cdc2 protein kinase. The protein also binds to double-stranded DNA. These data suggest that xnf7 may function as a transcription factor. During oocyte maturation, xnf7 is released into the cytoplasm and is not detectable in nuclei until the mid-blastula-gastrula stage of development. Western blot analysis of xnf7 isolated from oocytes and eggs showed the existence of multiple bands or isoforms of the protein. Unique isoforms that are generated during oocyte maturation are the result of phosphorylation. The phosphorylated isoforms remain in the cytoplasm until the mid-blastula stage. The re-accumulation of protein in the embryonic nuclei at this time correlates with the increase in abundance of the less phosphorylated isoforms. The xnf7 protein possesses a nuclear localization signal (NLS) similar to the bipartite signal found in nucleoplasmin. Newly synthesized xnf7 accumulated in the oocyte GV to detectable levels within a few hours following synthesis suggesting that retention of the protein in the cytoplasm during early cleavage may be due to a process that interferes with the function of the NLS. These data suggest that compartmentalization and/or post-translational modification of the nuclear protein xnf7 may be involved in regulating its function during early development.

Expression of rat serum amyloid A1 gene involves both C/EBP-like and NF kappa B-like transcription factors

Serum amyloid A (SAA) is a major acute-phase protein synthesized and secreted mainly by the liver. During inflammation, its expression is increased by 1000-fold as the result of greatly increased gene transcription. In this study, we analyzed the cis-acting regulatory elements and trans-acting factors important for the expression of the rat SAA1 gene. A DNA fragment containing 304 base pairs (bp) of 5'-flanking sequences of the SAA1 gene was fused to a reporter gene, chloramphenicol acetyltransferase (CAT), and the resulting construct, pSAA1/CAT (-304), was used to assess the function of the 5'-flanking sequences by transient transfection assay. pSAA1/CAT (-304) was not expressed or expressed at very low levels in both the liver- and nonliver-derived cells. However, when stimulated with conditioned medium prepared from mixed lymphocyte cultures, recombinant interleukin 1, or 12-O-tetradecanoylphorbol-13-acetate, expression of the pSAA1/CAT (-304) hybrid gene was induced 15-20-fold, but only in liver-derived cells. Further functional analysis demonstrated that a 66-bp DNA fragment conferred cytokine responsiveness onto a heterologous thymidine kinase promoter both in liver and nonliver cells. Footprint analysis with the Hep3B nuclear proteins revealed four protected regions in the 5'-flanking region of the SAA1 gene. The pattern of protection was identical with nuclear extracts prepared from either unstimulated or conditioned medium-treated Hep3B cells. Two of these footprint regions were identified as binding sites for C/EBP or C/EBP-related proteins, with the distal region having about 10-fold higher binding affinity than the proximal region. One additional cis-element formed a specific protein-DNA complex only with the nuclear proteins from TPA- or conditioned medium-treated Hep3B cells. This cis-element shares sequence identity with nuclear factor NF kappa B binding sites. The finding of a NF kappa B binding site within the 66-bp cytokine-responsive fragment further suggests its functional importance in the regulation of SAA1 gene expression. Our results suggest that C/EBP- and NF kappa B-related proteins may be important regulatory factors that contribute both to tissue specificity and to the high rate of SAA transcription in response to inflammatory mediators.