Bleaching of mouse rods: microspectrophotometry and suction-electrode recording.

When a substantial fraction of rhodopsin in a rod photoreceptor is exposed to bright light, the rod is desensitized by a process known as bleaching adaptation. Experiments on isolated photoreceptors in amphibians have revealed many of the features of bleaching adaptation, but such experiments have not so far been possible in mammals. We now describe a method for making microspectrophotometric measurements of pigment concentration and suction-electrode recording of electrical responses over a wide range of bleaching exposures from isolated mouse rods or pieces of mouse retina. We show that if pigment is bleached at a low rate in the presence of bovine serum albumin (BSA), and intermediate photoproducts are allowed to decay, mouse rods are stably desensitized; subsequent treatment with exogenous 11-cis retinal results in pigment regeneration and substantial recovery of sensitivity to the dark-adapted value. Stably bleached wild-type (WT) rods show a decrease in circulating current and acceleration of the time course of decay, much as in steady background light; similar effects are seen in guanylyl cyclase-activating protein knockout (GCAPs(-/-)) rods, indicating that regulation of guanylyl cyclase is not necessary for at least a part of the adaptation produced by bleaching. Our experiments demonstrate that in mammalian rods, as in amphibian rods, steady-state desensitization after bleaching is produced by two components: (1) a reduction in the probability of photon absorption produced by a decrease in rhodopsin concentration; and (2) an equivalent background light whose intensity is proportional to the fraction of bleached pigment, and which adapts the rod like real background light. These two mechanisms together fully account for the 'log-linear' relationship in mammalian retina between sensitivity and per cent bleach, which can be measured in the steady state following exposure to bright light. Our methods will now make possible an examination of bleaching adaptation and pigment regeneration in mouse animal lines with mutations or other alterations in the proteins of transduction.

The effect of milk proteins on appetite regulation and diet-induced thermogenesis.

BACKGROUND/OBJECTIVES: There is increasing evidence to support that a high-protein diet may promote weight loss and prevent weight (re)gain better than a low-protein diet, and that the effect is due to higher diet-induced thermogenesis (DIT) and increased satiety. However, data on the effect of different types of protein are limited. In the present study we compare the effect of whey, casein and milk on DIT and satiety. SUBJECTS/METHODS: Seventeen slightly overweight (29 ± 4 kg/m(2)) male subjects completed the study. The study had a randomized, crossover design, where the effect on 4 h postprandial energy expenditure (EE), substrate oxidation and subjective appetite sensation of three isocaloric test meals containing either a whey drink, a casein drink or skim milk was examined. Energy intake (EI) at a subsequent ad libitum lunch was also measured. RESULTS: There was no significant effect on subjective appetite sensation, but EI at lunch was lower after the milk test meal than after the casein (9%; P=0.0260) and the whey (9%; P=0.0258) test meals. Postprandial lipid oxidation was significantly higher after the casein test meal compared with the whey test meal (P=0.0147) when adjusted for baseline values. There was no significant difference in effect on EE, protein oxidation or carbohydrate oxidation. CONCLUSIONS: Milk reduced subsequent EI more than isocaloric drinks containing only whey or casein. A small but significant increase in lipid oxidation was seen after casein compared with whey.

Osteoarthritis - a role for weight management in rheumatology practice: an update.

Osteoarthritis (OA) and obesity are related diseases, which occur in a large proportion of the population. Epidemiological evidence show that weight is of great importance for the development of OA in the knee, and to some extent also in hip and finger joints. Once acquired, the OA contributes to further weight problems by decreasing the daily activity level. Weight loss will be beneficial for the knee and experimental data point at a highly significant effect on knee function and recent results even point at a positive effect on the cartilage of the knee joint. Recommending patients with a combination of knee OA and obesity to lose at least 5% body weight, and aim for 10% is predicted to correspond to 26% improvement in physical function. A programme for this weight loss has been tested with good results applying an initial formula diet with maintenance therapy in groups during follow-up.

A molecular marker that segregates with sorghum leaf blight resistance in one cross is maternally inherited in another.

Leaf blight-resistant sorghum accession SC326-6 was crossed to the susceptible cultivar BTx623 to analyze the genetic basis for resistance. Field scoring of inoculated F2 progeny revealed that resistance was transmitted as a dominant single-gene trait. By combining the random amplified polymorphic DNA (RAPD) technique with bulked-segregant analysis, it was possible to identify PCR amplification products that segregated with disease response. Primer OPD12 amplified a 323-bp band (D12R) that segregated with resistance. Creation of longer primers, or SCARs (sequence characterized amplified regions) for D12R resulted in the amplification of a single major band of the predicted size from all the resistant F2 progeny and the resistant parent SC326-6, but not from BTx623 or 24 of 29 susceptible F2 progeny. The SCAR primers also amplified a single band with DNA from IS3620C, the female parent in a cross with BTx623 that has been used to produce a recombinant inbred population for RFLP mapping. An equivalent band was amplified from all 137 recombinant inbred progeny, indicating that organelle DNA is the amplification target in this cross.

Contemporary global movement of emerging plant diseases.

Plant diseases are a significant constraint to agricultural productivity. Exotic plant diseases pose a continued threat to profitable agriculture in the United States. The extent of this threat has increased dramatically in the 1980s and 1990s due to the expansion of international trade in agricultural products and frequent movement of massive volume of people and goods across national boundaries. Introduction of new diseases has not only caused farm losses, but has also diminished export revenue since phytosanitary issues are linked to international commerce. Plant pathogens and their vectors have also moved across national boundaries, sometimes naturally and at other times influenced by the recent changes in trade practices. Sorghum ergot, Karnal bunt of wheat, potato late blight, and citrus tristeza are some of the most recent examples of enhanced importance of diseases due to the introduction of plant pathogens or vectors.

Induced resistance responses in maize.

Systemic acquired resistance (SAR) is a widely distributed plant defense system that confers broad-spectrum disease resistance and is accompanied by coordinate expression of the so-called SAR genes. This type of resistance and SAR gene expression can be mimicked with chemical inducers of resistance. Here, we report that chemical inducers of resistance are active in maize. Chemical induction increases resistance to downy mildew and activates expression of the maize PR-1 and PR-5 genes. These genes are also coordinately activated by pathogen infection and function as indicators of the defense reaction. Specifically, after pathogen infection, the PR-1 and PR-5 genes are induced more rapidly and more strongly in an incompatible than in a compatible interaction. In addition, we show that monocot lesion mimic plants also express these defense-related genes and that they have increased levels of salicylic acid after lesions develop, similar to pathogeninfected maize plants. The existence of chemically inducible disease resistance and PR-1 and PR-5 gene expression in maize indicates that maize is similar to dicots in many aspects of induced resistance. This reinforces the notion of an ancient plant-inducible defense pathway against pathogen attack that is shared between monocots and dicots.

Prospective study on the effect of smoking and nicotine substitution on leucocyte blood counts and relation between blood leucocytes and lung function.

BACKGROUND: The influence of smoking and of nicotine substitution on the counts of total blood leucocytes and leucocyte subsets and the relations between the counts and lung function was investigated. METHODS: The study was a combined cross sectional and prospective study of 298 smokers and 136 non-smokers. Forced expiratory volume in one second (FEV1) was measured in all participants at baseline and six months after quitting smoking in 160 ex-smokers (quitters) and 138 persons with smoking relapse. Blood samples were obtained from all participants at baseline and from 160 quitters and 30 continuing smokers two, six, 12, and 26 weeks after smoking cessation and from 92 quitters one year after the cessation of smoking. RESULTS: Blood leucocyte counts and leucocyte subsets were all higher in smokers than in non-smokers. In cigarette smokers total leucocyte, neutrophil, and lymphocyte blood counts showed a dose dependent relationship with the daily cigarette consumption and pack years consumption. In smokers the neutrophil blood count was independently associated negatively with FEV1 residuals. After quitting smoking total leucocyte, neutrophil, and lymphocyte blood counts decreased during the first 26 weeks and after one year lymphocyte blood counts were higher than in non-smokers. In quitters substituted with nicotine chewing gum (2 mg) the accumulated number of pieces of chewing gum used in the 12 weeks had an inverse relationship with the decrease in the total lymphocyte blood count at 12 weeks after smoking cessation. CONCLUSIONS: Leucocyte blood counts are raised in smokers and decrease after smoking cessation. Neutrophil blood counts had an inverse relationship with lung function and nicotine may increase lymphocyte blood counts in smokers.

Genetic Structure and Temporal Dynamics of a Colletotrichum graminicola Population in a Sorghum Disease Nursery.

ABSTRACT Restriction fragment length polymorphisms (RFLPs) were used to study the population genetics of Colletotrichum graminicola (= C. sublineolum), the causal agent of sorghum anthracnose. Screening of 80 anonymous probes from a genomic library detected polymorphisms in 81% of 299 probe-enzyme combinations among nine international isolates. Seven single- or low-copy probes were used to study a collection of 411 isolates sampled during 1991 to 1993 from a sorghum disease nursery in Georgia. Nei's gene diversity was moderately high, with = 0.215 on average, while genotypic diversity was extremely low with an average genotypic diversity value of G = 1.513. Only nine multilocus haplotypes were identified, with one haplotype being present at a frequency of approximately 80% each year. Two other haplotypes were found at significant frequencies (4 to 10%). Allele and haplotype frequencies did not differ over the 3 years, indicating that this population was stable. Our findings suggest that genetic drift and gene flow were not major contributors to genetic structure, while asexual reproduction had a significant effect.

[Effect of indomethacin on the intracranial pressure]. / Indomethacins virkning på det intrakranielle tryk.

Twenty patients subjected to craniotomy for supratentorial cerebral tumours were anaesthetized with thiopental, fentanyl, nitrous oxide, and isoflurane. A PaCO2 level averaging 4.8 kPa was achieved. The patients were randomized to intravenous indomethacin 50 mg or placebo administrated after exposure of the dura. A significant decrease in intracranial pressure from 6.5 to 1.5 mmHg (medians) was found after indomethacin administration. This decrease was caused by a significant decrease in cerebral blood flow associated with a significant increase in the arterio-venous oxygen difference. Indomethacin did not affect cerebral oxygen uptake, arteriovenous difference in lactate or the lactate/oxygen index, suggesting that indomethacin did not provoke global cerebral ischaemia. In the indomethacin group, dura was sufficiently relaxed in eight of nine patients, and dura was opened without the occurrence of cerebral swelling. In the placebo group, mannitol supplemented with hypocapnia was applied in five patients. These findings suggest that perioperative treatment with indomethacin is an excellent treatment of intracranial hypertension during normocapnic isoflurane anaesthesia for craniotomy.

Effects of perioperative indomethacin on intracranial pressure, cerebral blood flow, and cerebral metabolism in patients subjected to craniotomy for cerebral tumors.

This study was carried out to evaluate the effects of perioperative indomethacin on intracranial pressure (ICP), cerebral blood flow (CBF), and cerebral metabolism. Twenty patients subjected to craniotomy for supratentorial cerebral tumors were anesthetized with thiopental, fentanyl, nitrous oxide, and isoflurane. A PaCO2 level averaging 4.8 kPa (median) was achieved. The patients were randomized to intravenous indomethacin 50 mg or placebo administrated after exposure of the dura. ICP was measured continuously subdurally with a 22-gauge canula connected to a transducer. CBF and the arteriovenous difference of oxygen (AVDO2) were measured twice, before and after indomethacin/placebo administration. A significant decrease in ICP from 6.5 to 1.5 mm Hg (median) was found after indomethacin administration. This decrease was caused by a significant decrease in CBF associated with a significant increase in AVDO2. Indomethacin did not affect the cerebral metabolic rate of oxygen, the arteriovenous difference of lactate, or the lactate/oxygen index, suggesting that indomethacin did not provoke global cerebral ischemia. In the indomethacin group, dura was sufficiently relaxed in eight of nine patients and dura was opened without the occurrence of cerebral swelling. In one patient, mannitol treatment was necessary to prevent dural tightness. In the placebo group, mannitol supplemented with hypocapnia was applied in five patients. These findings suggest that perioperative treatment with indomethacin is an excellent treatment of intracranial hypertension during normocapnic isoflurane anesthesia for craniotomy.

DNA markers for downy mildew resistance genes in sorghum.

The random amplified polymorphic DNA technique was used to find markers for a downy mildew resistance gene in sorghum. Of the 674 random primers screened for polymorphism, 2 amplified fragments were linked to a downy mildew resistance gene in sorghum line SC414. Utilization of an existing restriction fragment length polymorphism mapping population (IS3620C x BTx623) also revealed two markers that are linked to a different resistance gene in another sorghum line, BTx623.

Genetics of nonsenescence and charcoal rot resistance in sorghum.

Nonsenescence is a delayed leaf and plant death resistance mechanism in sorghum that circumvents the detrimental effects of reduced soil moisture combined with high temperatures during post-anthesis growth. This drought-tolerance mechanism is often equated with charcoal rot resistance, a widespread root and stalk disease of great destructive potential. Therefore, the inheritance of charcoal rot resistance was investigated directly, by exposure of sorghum to Macrophomina phaseolina, the causal organism, and indirectly, by determination of the inheritance of nonsenescence. Sorghum families derived from diallel crosses between two nonsenescent, resistant inbreds (B35, SC599-11E) and two senescent, susceptible inbreds (BTx378, BTx623) were evaluated in 1989 at College Station and at Lubbock, Texas, under controlled and field conditions. We determined that nonsenescence was regulated by dominant and recessive epistatic interactions between two nonsenescence-inducing loci and a third locus with modifying effects. The same conclusion was reached for charcoal rot resistance. The presence of different genetic mechanisms within SC599-11E for nonsenescence and charcoal rot resistance verifies that these two forms of resistance are not different manifestations of a single trait, i.e., they are not to be equated with each other. We conclude that nonsenescence alone cannot account for, and should not be used as the sole breeding criterion for, resistance to charcoal rot in sorghum.

Length heterogeneity in ITS 2 and the methylation status of CCGG and GCGC sites in the rRNA genes of the genus Peronosclerospora.

The polymerase chain reaction (PCR) was used with primers complementary to conserved flanking sequences to amplify the internal transcribed spacer 2 (ITS 2) of the rDNA repeat units of five Peronoscleropora isolates, one each of P. sorghi, P. maydis, P. sacchari and two of P. zeae. In contrast to the situation found in most-fungi that have been examined, length heterogeneity was evident in each sample. The rDNA composition of the amplified bands was confirmed by Southern hybridizations using an ITS 2 amplified from P. sorghi and cloned rDNA from Neurospora crassa as probes. Length heterogeneity was also detected in genomic DNA digests using the same probes. In addition to one dominant fragment for each isolate, there were several less frequent fragments of different sizes, and the isolate(s) for each species had a unique banding pattern for ITS 2. The absence of 5-methylcytosine residues in CCGG and GCGC sequences in the ribosomal genes of these four Peronosclerospora species was demonstrated by the production of identical banding patterns with ribosomal DNA probes following digestion of genomic DNA with MspI and HpaII, and by complete digestion with CfoI.

Use of an A-T-rich DNA clone for identification and detection of Peronosclerospora sorghi.

A recombinant plasmid, pMLY12-1, screened from a Peronosclerospora sorghi library hybridizes only to DNA of P. sorghi, or to DNA from leaves infected with P. sorghi, not to DNA of P. sorghi Thailand isolate, P. philippinensis, P. sacchari, or P. maydis. The terminal sequences of the 1.3-kb insert, which appears to contain mitochondrial DNA, are 85% A and T. No polymorphisms were detected when the probe was hybridized to Southern blots containing DNA from P. sorghi pathotype 1, pathotype 3, or a Botswana isolate digested with any of the eight restriction endonucleases tested. The banding patterns were the same whether DNA was extracted directly from the fungus or from infected leaves.

Implication of Gibberellins in Head Smut (Sporisorium reilianum) of Sorghum bicolor.

The head smut fungus, Sporisorium reilianum ([Kuhn] Landon and Fullerton), was shown to reduce plant height in infected Sorghum bicolor ([L.] Moench) plants. The major reductions occurred in the internodes nearest the panicle and were more severe in naturally infected than in inoculated plants. Less affected plants developed reproductively sterile panicles, and eventually smutted panicles developed phyllodied growths which progressed into leafy shoots. Extracts of smutted, sterile, and healthy (control) panicles of field-grown plants exhibited gibberellin (GA)-like activity in the dwarf rice bioassay. When extracts were purified and assayed with deuterium-labeled GA standards by gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM), GA(1), GA(3), GA(19), GA(20), and GA(53) were detected based on coelution with the standards, identical Kovats retention index values, and matching ion masses and relative abundances for three major ions. In addition, based on published Kovats retention index values, ion masses, and relative abundance values, GA(4), GA(7), GA(8), GA(14), GA(29), and GA(44) were tentatively identified. Quantitative analysis revealed that panicles of healthy control plants contained from 60 to 100% higher total concentrations of GAs than panicles of smutted plants. These comparisons were most striking for the early 13-hydroxylation pathway precursors GA(53), GA(44), and GA(19) but not for GA(20). Extracts of S. reilianum sporidia and culture medium exhibited GA-like bioactivity, and GA(1) and GA(3) were detected based on GC-MS-SIM assay with (2)H-labeled internal standards. Quantitative analysis of these GAs showed increasing concentrations from 4 to 7 to 10 days of culture and a decline at 20 days. This is the first GC-MS-SIM detection of GAs in a non-Ascomycete fungus, and the disease symptoms and quantitative data suggested that fungal infection may interfere with biosynthesis of GAs by the host plant.

Intracoronary thrombolysis in patients with acute myocardial infarction: comparison of the efficacy of urokinase with streptokinase.

The efficacy of intracoronary urokinase and streptokinase were compared in 80 patients with acute myocardial infarction in a prospective, randomized, double-blind study. Urokinase was infused into the occluded coronary artery at 6000 U/min, and streptokinase was infused at 2000 U/min. Maximal duration of infusion was 2 hr. The frequency of successfully opening the artery was similar for patients receiving urokinase (27 of 45, 60%) and those receiving streptokinase (20 of 35, 57%). Fibrinogen levels after infusion were measured in 63 patients. Nineteen of 29 streptokinase recipients had fibrinogen levels less than 100 mg/dl compared with levels of two of 34 urokinase recipients (p less than .001). Five of 45 (11%) patients receiving urokinase and 10 of 35 receiving streptokinase (29%) had bleeding complications (p less than .05). Major bleeding after early coronary artery bypass surgery was more frequent in the streptokinase group (four of five compared with a similar group of patients receiving urokinase (none of five). This study demonstrates that while urokinase and streptokinase have equal intracoronary thrombolytic efficacy, patients receiving urokinase have less systemic fibrinolysis and less perioperative bleeding with early surgery than do patients receiving streptokinase.

Clinical and echocardiographic manifestations of a thrombosed Bjork-Shiley aortic valve.

A 36-year-old woman with a Bjork-Shiley prosthetic aortic valve developed acute congestive heart failure and pulmonary edema. She was found to have a new diastolic murmur, absence of valve clicks, and an immobile prosthetic disk as shown by echocardiography. At surgery the valve, which was covered with fibrin and thrombus, was replaced, and she did well following operation.