[An investigation of the effect of rostral ventrolateral medulla lesion on pressor response induced by electrical stimulation of hypothalamic paraventricular nucleus in the cat]

The experiments were performed on 20 adult cats anesthetized with chloralose and urethane, paralyzed and artificially ventilated. The rostral ventrolateral medulla (RVL) was explored by electrical stimulation. We found that an area, 3-5 mm rostral to the obex, 3-4 mm lateral to the midline, and 0-1 mm from the ventral surface of the medulla, was the most effective region for producing a pressor response. After bilateral microinjection of kainic acid into or electrolytic lesion of the above-mentioned active RVL area, a large decrease in arterial blood pressure was elicited, and the pressor response induced by electrical stimulation of the hypothalamic paraventricular nucleus (PA) was nearly eliminated. The results suggest that the RVL mediates the PA pressor response.

[Study on the color modification buring surface staining of PLAT castable ceramic restorations]

The surface staining of castable ceramic restorations is a technique-dependent process. So it is inevitable that the color of restorations mismatch the color of natural teeth. This study was conducted to explore the possibility of modifying the color by selected use of special colored stains. Eighty PLAT castable ceramic samples were machined, 16 mm in diameter, 1.2 mm in thickness. Thirty-two samples were stained with yellow stain and 32 samples orange. Sixteen samples were stained with red, green, blue and violet stains, respectively. To the yellow and orange stained samples, we applied correspondingly the same stain, red, green, blue and violet stains. The color of each sample was evaluated with a colorimeter and translated to Munsell notations. The results indicated that chroma was intensified by each application of the same stain. Red and green stains made the hue reddish and greenish. Blue and violet stains could effectively decrease the chroma of yellow or orange. Meanwhile, the hue was also slightly changed to greenish and reddish.

Clothing prevents ultraviolet-B radiation-dependent photosynthesis of vitamin D3

Photoprotection of the skin is mainly a function of clothing, although the effectiveness of the latter against UV-B solar radiation (wavelengths 290-320 nm) has not been measured in vivo. Since UV-B mediates the cutaneous formation of vitamin D3, we examined the attenuation of that photosynthetic reaction by the commonly used fabrics cotton, wool, and polyester in black and white colors. Direct transmission of UV-B was attenuated the most by black wool (98.6% of incident irradiance) and the least by white cotton (47.7%). None of the fabrics allowed the photoproduction of previtamin D3 from 7-dehydrocholesterol irradiated in vitro with up to 40 min of simulated sunlight or the elevation of serum vitamin D3 after irradiation with approximately one minimal erythema dose (MED) of UV-B in volunteers wearing jogging garments made of these fabrics. Increasing the whole body irradiation dose to six MEDs still failed to produce a serum vitamin D3 response in garment-clad subjects. Regular (seasonal) street clothing also prevented an elevation of the vitamin D3 in response to UV-B radiation. We conclude that clothing prevents or significantly impairs the formation of vitamin D3 after photostimulation with up to six MEDs of UV-B.

Early markers of pancreas transplant rejection

To compare the predictive value of urinary amylase (UA), urinary insulin (UI), and urinary prostaglandin (PGE2), whole pancreas isografts or allografts from (ACI rat donors, RT1a) with bladder drainage of exocrine secretions were performed in Lewis rats (RT1(1)) with streptozotocin-induced diabetes. UA, UI, PGE2 and plasma glucose levels were measured daily. Euglycemia was restored on Postoperative Day 1 in all the recipients of isografts (N = 6) and was maintained for over a year. UI concentrations and PGE2 outputs were stable, with low levels ranging between 0.3 +/- 0.2 to 7 +/- 2 ng/ml and 56 +/- 15 to 164 +/- 48 ng/24 hr, respectively, while UA levels were significantly elevated compared to normal controls (> 1,000 U/ml vs 29 +/- 16 U/ml). In the allograft group (N = 12), rejection occurred on Days 7 through 9, with a mean graft survival time of 8.1 +/- 0.1 days. UA dropped from a post-transplant peak of 2,422 +/- 353 U/ml on Postoperative Day 4 to below 1,380 +/- 256 U/ml 3 days before rejection (Day -3). UI increased to 83 +/- 16 ng/ml (P < 0.05) on Day -6 and reached a post-transplant peak of 140 +/- 24 ng/ml on Day -5, while PGE2 output rose from a pretransplant level of 18 +/- 2 to 92 +/- 25 ng/24 hr on Postoperative Day 1, followed by a significant elevation on Day 4 (-4).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic observation and treatment approach for patients with angina decubitus

In order to investigate the mechanism and treatment of angina decubitus, 20 patients (18 men and 2 women aged 36-70 years) were studied during hospitalization. All patients were found to have an increased heart rate x systolic blood pressure product before the onset of angina decubitus, indicating that this type of angina pectoris belongs to the category of effort angina. Of the 11 patients investigated by continuous hemodynamic monitoring, 3 had significant progressive increases in pulmonary artery systolic pressure (PASP) and pulmonary artery diastolic pressure (PADP) before onset: their episodes of angina could not be completely controlled by digoxin and diuretics, but quickly subsided after beta blockers were added. Among the other 8 patients, PADP increased slightly in 5 and remained unchanged in 3 cases before onset: these patients had no manifestations of LV dysfunction, and beta blockers combined with coronary vasodilators produced satisfactory effects. These results indicate that LV failure is not a major factor in the pathogenesis of angina decubitus. The LV diastolic dysfunction seen in 8/11 cases may have been related to LV hypertrophy caused by long-term hypertension or chronic persistent ischemia.

Identification of an African swine fever virus gene with similarity to a myeloid differentiation primary response gene and a neurovirulence-associated gene of herpes simplex virus

Here we describe an open reading frame (LMW23-NL) in the African swine fever virus genome that possesses striking similarity to a murine myeloid differentiation primary response gene (MyD116) and the neurovirulence-associated gene (ICP34.5) of herpes simplex virus. In all three proteins, a centrally located acidic region precedes a highly conserved, hydrophilic 56-amino-acid domain located at the carboxy terminus. LMW23-NL predicts a highly basic protein of 184 amino acids with an estimated molecular mass of 21.3 kDa. The similarity of LMW23-NL to genes involved in myeloid cell differentiation and viral host range suggests a role for it in African swine fever virus host range.

[Study on casting precision of plat castable ceramic crowns]

The plat castable ceramic crown was made with investment material prepared in our college with our own casting technique by a Chinese-made casting machine. The accuracy and fitness of the crown were studied and appraised. Results show that the margin of fitness is 46 microns and that the cement film thickness of the dies in the spacer material group is 65.13 microns. Hence the results are satisfactory. The Plat castable ceramic crown might be used in clinical dentistry.

Myelin proteolipid protein: minimum sequence requirements for active induction of autoimmune encephalomyelitis in SWR/J and SJL/J mice

Proteolipid protein (PLP) is the major protein constituent of mammalian central nervous system myelin. We have previously identified two different PLP encephalitogenic T cell epitopes in two mouse strains. Murine PLP peptides 103-116 YKTTICGKGLSATV and 139-151 HCLGKWLGHPDKF are encephalitogenic determinants in SWR/J (H-2q) and SJL/J (H-2s) mice, respectively. The purpose of the present study was to determine the minimum sequence requirements for each of these PLP encephalitogens. In SWR/J mice, at least two distinct overlapping peptides can induce experimental autoimmune encephalomyelitis (EAE). The eleven residue sequences PLP 105-115 TTICGKGLSAT and PLP 106-116 TICGKGLSATV are encephalitogenic in SWR/J mice, but PLP 106-115 TICGKGLSAT, the decapeptide indigenous to both sequences, is non-encephalitogenic. In contrast, the shortest PLP sequence capable of inducing EAE in SJL/J mice is the nonapeptide 141-149 LGKWLGHPD. These data indicate that encephalitogenic determinants of PLP are short contiguous peptide sequences similar in length and diversity to those of MBP.

(Aminoalkoxy)chromones. Selective sigma receptor ligands

A series of (aminoalkoxy)chromones has been prepared, members of which bind potently (16-100 nM) at the sigma binding site and bind weakly (greater than 1000 nM) at the dopamine D2 receptor and 33 other receptors, second messenger systems, and ion channels. At the sigma receptor, the preferred position of attachment for the aminoalkoxy side chain to the chromone ring followed the rank order: 7-position greater than 5-position greater than 6-position. Chromones that contained a 2-substituent that was not coplanar with the chromone ring system showed improved binding over compounds with coplanar substituents. The most potent compound at the sigma site, 7-[[7-(4-hydroxypiperidyl)heptyl]oxy]-2-phenylchromone (74), had receptor affinities (IC50) of 16 nM at the [3H]DTG site, 19 nM at the [3H]-(+)-3-PPP site, and 4000 nM (Ki) at the dopamine D2 receptor. The most selective compound examined, 6-[[6-(4-hydroxypiperidyl)hexyl]-oxy]-2-cyclopentylchromone (58), exhibited IC50s of 51 nM at the [3H]DTG site, 55 nM at the [3H]-(+)-3-PPP site, and 21,000 nM (Ki) at the dopamine D2 receptor. Compound 44 (6-[[6-(4-hydroxypiperidyl)hexyl]oxy]-3-methylflavone, NPC 16377) was systemically effective (ip and po) in two behavioral models predictive of antipsychotic compounds and systemically active in animal models of ischemia.

Effects of Ca2+ on the kinetics of phosphate release in skeletal muscle

The process of phosphate dissociation during the muscle cross-bridge cycle has been investigated by photoliberation of inorganic phosphate (Pi) within skinned fibers of rabbit psoas muscle. This permitted a test of the idea that Ca2+ controls muscle contraction by regulating the Pi release step of the cycle. Photoliberation of Pi from structurally distinct "caged" Pi precursors initiated a rapid tension decline of up to 12% of active tension, and this was followed by a slower tension decline. The apparent rate constant of the fast phase, kPi, depended on both [Pi] and [Ca2+], whereas the slow phase generally occurred at 2-4 s-1. At maximal Ca2+, kPi increased in a nonlinear manner from 43 +/- 2 s-1 to 118 +/- 7 s-1, as Pi was raised from 0.9 to 12 mM. This was analyzed in terms of a three-state kinetic model in which a force-generating transition is coupled to Pi dissociation from the cross-bridge. As Ca(2+)-activated tension was reduced from maximal (Pmax) to 0.1 Pmax, (i) kPi decreased by up to 2.5-fold, (ii) the relative amplitude of the rapid phase increased 2-fold, and (iii) the relative amplitude of the slow phase increased about 6-fold. Changes in the rapid phase are compatible with Ca2+ influencing an apparent equilibrium constant for the force-generating transition. By comparison, kPi was faster than the rate constant of tension redevelopment, ktr, and was influenced less by Ca2+. Ca2+ effects on the caged Pi transient cannot account for the large effects of Ca2+ on actomyosin ATPase rates or cross-bridge cycling kinetics but may be a manifestation of reciprocal interactions between the thin filament and force-generating cross-bridges, and may represent Ca2+ regulation of the distribution of cross-bridges between non-force-and force-generating states.

Enhanced Photosynthesis and Stomatal Conductance of Pima Cotton (Gossypium barbadense L.) Bred for Increased Yield

Yield of Pima cotton (Gossypium barbadense L.) has tripled over the last 40 years with the development of new cultivars. Six genetic lines representing successive stages in the breeding process (one primitive noncultivated accession, four cultivars with release dates from 1949 to 1983, and one unreleased breeding line) were grown in a greenhouse, and their gas exchange properties were compared. Among the cultivated types, genetic advances were closely associated with increasing single-leaf photosynthetic rate (A) and stomatal conductance (g(s)), especially in the morning. The A and g(s) of the primitive line approached those of the cultivated types early in the morning, but were much lower for the rest of the day. In both morning and afternoon, A was correlated with g(s) across genotypes but was not correlated with leaf thickness, concentrations of chlorophyll or starch, or intercellular CO(2) concentration (c(i)). In the oldest cultivar, the relationship of A to c(i) did not change between morning and afternoon. In the two most recent lines, the slopes of the A:c(i) curves at limiting c(i) exceeded that of the oldest cultivar by 25 to 50% in the morning, but the differences were much smaller in the afternoon. The maximum A of the newer lines at high c(i) exceeded that of the oldest cultivar only in the morning. Breeding for increasing yield has enhanced the photosynthetic capacity and stomatal conductance of Pima cotton and altered the diurnal regulation of photosynthesis.

Intravenous recombinant tissue-type plasminogen activator in acute myocardial infarction

The efficacy and safety of intravenously administered recombinant tissue-type plasminogen activator (rt-PA, Boehringer Ingelheim Corp.) was investigated in 10 patients with acute myocardial infarction (AMI). rt-PA was given as a 10 mg bolus dose followed by infusions of 50 mg, 20 mg and 20 mg in three successive hours. All patients underwent baseline coronary angiography before thrombolytic therapy. Ninety minutes after the initiation of rt-PA infusion, recanalization of infarct-related coronary arteries as confirmed by angiography was achieved in 7 patients. The largest reduction in circulating fibrinogen was observed 4 to 6 h after the start of rt-PA infusion--14.3%. Moderate hemorrhage at the sites of arterial puncture occurred in 2 cases, probably as a result of heparin anticoagulation. No other side effects occurred. So rt-PA is an effective and safe thrombolytic agent.

Secondary prevention of myocardial reinfarction with low dose aspirin

A clinical trial of secondary prevention of reinfarction with low dose aspirin is reported. 50 mg aspirin per day was administered in 216 case. 211 cases did not take aspirin or any other antiplatelet agents as a control group. The follow-up periods in the two groups were 19.4 +/- 12.6 mon and 20.7 +/- 13.0 mon, respectively. There were 175 males in the aspirin group and 137 males in the control group. The incidence of reinfarction was reduced by 65% and platelet aggregation was inhibited obviously in the aspirin group as compared to the control group in men, whereas no significant trends were observed in women.

[Isolation and purification of human brain creatine kinase (CK-BB)]

A improved method for isolation and purification of CK-BB from human brain is introduced. CK-BB of fraction IV was purified to approximately 306.9 fold as compared with homogenate of human brain. The specific activity was 322.2 IU/mg protein. The recovery of creatine kinase activity was 52.8%. This fraction was analyzed by SDS-PAGE. It showed a single major band with an estimated molecular weight of 43000 when it stained with coomassie blue. Purity of fraction V was much better than fraction IV, but some CK activity was lost.

Chemical synthesis and surface activity of lung surfactant phospholipid analogs. II. Racemic N-substituted diether phosphonolipids

A series of racemic 16:0 disaturated N-substituted diether phosphonolipid analogs of glycerophospholipids have been synthesized and purified. Isosteric methylene substitution at three of the four ester sites (carboxyl, phosphate) of conventional glycerophospholipids enhanced the hydrophobicity of analog compounds compared with dipalmitoyl phosphatidylcholine (DPPC), the major glycerophospholipid component of lung surfactant. Further substitutions at the nitrogen headgroup also contributed to hydrophobicity/hydrophilicity characteristics, as well as allowing graded variations in headgroup size among the members of the diether phosphonolipid analog series. Interfacial property studies showed that these compounds had significant differences in surface activity characteristics compared with DPPC, including increased adsorption and respreading facility, plus an enhanced ability to generate low surface tension (less than 1 to 4 mN/m) on an oscillating bubble apparatus at 37 degrees C. In addition, pressure-volume mechanical studies in surfactant-deficient excised rat lungs showed that the diether phosphonate analog of DPPC could partially restore pressure-volume characteristics toward normal, both as a pure component and in binary mixtures with palmitoyl-oleoyl phosphatidylglycerol. These findings suggest that selected analog compounds, synthesized with relatively small structural modifications from biologic glycerophospholipids, may have eventual applications as components of synthetic exogenous lung surfactants. Of more immediate importance, analog molecules with defined structural variations are convenient molecular probes for developing structure-surface activity correlates for phospholipid-like surfactants and for investigating the specificity of interactions between glycerophospholipids and other compounds such as proteins.

Chemical synthesis and surface activity of lung surfactant phospholipid analogs. III. Chiral N-substituted ether-amide phosphonolipids

A homologous series of chiral (R) ether-amide phosphonolipid analogs of naturally occurring (R) glycerophospholipids were synthesized and characterized for their interfacial behaviors. The phosphonolipids possess isoteric ether, amide, and phosphonate functions at positions corresponding to the sn-1, sn-2, and sn-3 ester functions, respectively, of naturally occurring glycerophospholipids. All compounds were synthesized with disaturated C16:0 alkyl/acyl moieties to give structural analogy with dipalmitoyl phosphatidylcholine (DPPC), the major glycerophospholipid component of lung surfactant. Further substitutions at the headgroup nitrogen were also used to generate differences in headgroup size and polarity in the synthetic compounds. The surface activity of the ether-amide phospholipids was investigated in terms of adsorption to the air-water interface, together with studies of dynamic respreading after monolayer collapse and surface tension lowering in dynamically compressed spread films and dispersions. Results showed that several ether-amide phosphonolipids had more rapid adsorption and improved dynamic respreading behavior compared to DPPC, plus the ability to lower surface tension into the range of less than 1 to 4 mN/m in spread films and in dispersions under dynamic conditions. In combination with a series of diether phosphonolipids synthetized in a companion study [1], these ether-amide compounds are useful in the development of molecular structure-surface activity correlates for lung surfactant-related materials, and should assist in investigating the specificity of interactions between phospholipids and other pulmonary biological molecules.

Adenosine 5'-triphosphate increases acetylcholine channel opening frequency in rat skeletal muscle

1. The effects of extracellular adenosine 5'-triphosphate (ATP) on the acetylcholine (ACh) channel opening activity was studied in dissociated rat skeletal muscle cells using patch-clamp recording techniques in cell-attached configuration. 2. With 10 microM-ATP in the recording pipette, the spontaneous opening frequency on the the alpha-bungarotoxin-sensitive ACh channel increased significantly from 0.3 to 4.7 s-1, although the opening frequency was not as high as that activated by very low (0.4 microM) ACh concentrations (64 s-1). 3. Spontaneous ACh channel openings, and ATP-associated and ACh-activated channel openings had similar single-channel conductances, 55, 59 and 56 pS, respectively. 4. ATP-associated events and spontaneous ACh channel opening events had similar mean channel open durations (0.6 ms); however, these values were considerably shorter than the duration of ACh-activated events (2 ms). 5. Pre-treatment with alpha-bungarotoxin (100 nM) blocked spontaneous ACh channel openings, ATP-associated openings and ACh-activated openings. 6. When delivered through a separate drug pipette after the formation of a gigaseal, ATP increased ACh-activated single-channel open probability in a dose-dependent fashion. 7. The increase in channel open probability was due primarily to the increase in channel opening frequency. ATP did not significantly alter the mean channel open duration or the single-channel conductance. 8. The ATP analogue adenosine-5'-O-(3-thiotriphosphate) (ATP-gamma-S) also enhanced ACh-activated channel open probability with relatively less potency. ADP, AMP and adenosine (up to 1 mM) did not significantly increase ACh channel open probability. 9. It is concluded that ATP in the micromolar range facilitates both spontaneous and agonist-activated ACh channel opening. The facilitation is due to ATP itself and not to products of ATP hydrolysis. The facilitatory actions of ATP on ACh channels are manifested by the increase in the channel opening frequency, and they may be mediated by an intracellular second messenger.

Adenosine derived from hydrolysis of presynaptically released ATP inhibits neuromuscular transmission in the rat

It has been established that ATP is released from motor nerve terminals and that exogenous ATP depresses end-plate potential (e.p.p.) amplitudes. This study assessed whether presynaptically released ATP reduced e.p.p.s. E.p.p.s in the rat extensor digitorum longus muscle were depressed by exogenous ATP and adenosine. If ATP hydrolysis to adenoisine was blocked, however, ATP had no effect. Addition of theophylline increased e.p.p. amplitude due to removal of the depressant effect caused by ATP contained in the quantal release. This inhibition was absent when the rate of release was reduced by high Mg2+. It is concluded that e.p.p. inhibition is mediated by adenosine derived from presynaptically released ATP.