Determination of lansoprazole and five metabolites in plasma by high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of lansoprazole, a new proton-pump inhibitor, and five of its metabolites in human plasma is described. Lansoprazole, its metabolites, and internal standard (omeprazole) were extracted into diethyl ether-methylene chloride and separation was obtained using a reversed-phase column under isocratic conditions. The method features monochromatic ultraviolet detection at 285 nm, and single extraction, single evaporation sample handling. The lower limit of quantitation, based on standards with acceptable coefficients of variation, was 10 ng/ml for all compounds. No endogenous compounds were found to interfere. This method has been demonstrated to be suitable for pharmacokinetic studies in humans.

Quantitative reflection spectrophotometry: spatial and temporal variation of Hb oxygenation in human skin

Applying a fast scanning reflection spectrophotometer and multicomponent spectra analysis, oxygen saturation (SHb) and relative concentration (CHb) of hemoglobin in the skin were determined at eight skin sites in 11 healthy persons. SHb was significantly higher at the tip of the index finger and big toe (90 +/- 3.9 and 92 +/- 4.2%, respectively) compared with the forehead, volar forearm, back of hand, abdomen, calf and forefoot where mean values varied between 52 and 67% (p < 0.001). CHb also was higher at acral sites (big toe: 2.04 +/- 0.14 arbitrary units (AU); index finger: 2.13 +/- 0.19 AU) than at the other locations (p < 0.0001) where it was between 0.56 +/- 0.12 AU (abdomen) and 0.95 +/- 0.28 AU (forefoot). In the course of time, rhythmical oscillations of both parameters at a frequency of 3-5/min were seen in 68% of the measurements, predominantly at the six proximal sites. Heating the measuring site to 44 degrees C caused a biphasic increase of CHb and SHb which was significant at the proximal sites (p < 0.0001). SHb values came into the range of arterial blood. Temporal and spatial variation of both parameters decreased. Reflection spectrophotometry gives the possibility to directly assess dermal hemoglobin saturation, its physiological variability and reactions to provocation stimuli. Concentration and saturation of hemoglobin in dermal vessels appear definitely different at acral compared with proximal sites.

Skin oxygen pressure histograms in patients with peripheral arterial occlusive disease during intraarterial and intravenous prostaglandin E1 infusions of different dosages and their prognostic value

Skin surface oxygen pressure fields (tcPO2 [37 degrees C]) reproducibly characterize skin microcirculation in patients with peripheral arterial occlusive disease. These appear suited for investigation of short- and long-term effects of vasoactive drug treatment. The authors studied whether skin surface oxygen pressure histograms change depending on dosage and route of administration of prostaglandin E1 (PGE1), whether they are of predictive value for patients' clinical outcome, and whether they normalize after therapy with PGE1. The authors investigated 15 patients with various degrees of disease and measured forefoot oxygen histograms consisting of at least 80 single tcPO2 (37 degrees C) values before and during intraarterial infusion (1.5, 3, or 6 ng/kg/minute) and intravenous infusion (4.5, or 9 ng/kg/minute). The measurements were repeated two and six hours after the end of intraarterial application of 1.5 ng/kg/minute. Furthermore, the orthostatic vasoconstrictor response was tested. Skin oxygen pressure histograms were controlled after a period of twenty-two (mean) days of intraarterial PGE1 therapy. Resting histograms were left shifted with median tcPO2 (37 degrees C) between 1 and 7 mm Hg. During intraarterial application, histograms were shifted to lower tcPO2 (37 degrees C) values in most patients. Only in 3 diabetic subjects with proximal or acral obliterations was a marked increase observed. The alterations were detectable at least two hours after the end of the infusion. During intravenous infusion, histograms did not change in most cases. After long-term therapy, histograms were substantially unchanged. A pathologic vasoconstrictor response, which was present in 10 patients, could not be restored. Despite a marked deterioration of the histograms the clinical outcome was favorable in 7 patients. Patients with a high resting tcPO2 (37 degrees C) (median 4 mm Hg and more) and those with a vasoconstriction on orthostasis are likely to respond to PGE1 therapy.

[Traumatically-induced ischemia of the hands]

BACKGROUND

The widely unknown hypothenar hammer syndrome (HHS) is caused by chronic mechanical trauma; in these cases the hypothenar is used as a tool. This may cause intimal lesions of the ulnar artery usually near the hamate bone resulting in thrombosis or aneurysms.

PATIENTS

Six patients with HHS are presented. In four cases occupational activities were most probable cause for HHS, in two patients sport activities.

DIAGNOSIS

Clinical examination already indicates insufficient blood supply in the supply area of the ulnar artery. Non invasive methods of examination are doppler measurements of hand arteries and occlusion plethysmography of finger arteries. For differential diagnosis capillaroscopy, laboratory tests and hand arteriography can be necessary.

THERAPY

Avoiding the releasing cause is main part in therapy of HHS. Only in few patients special medical treatment is indicated.

CONCLUSION

Positive evidence of causal relationship between occupational exposure and appearance of HHS has to be acknowledged as occupational disease.

[A nomogram of duplex ultrasound quantification of peripheral arterial stenoses. Studies of the cardiovascular model and in angiography patients]

BACKGROUND AND METHODS

Blood flow velocity measurements were performed with duplex ultrasound in vitro (flow phantom) and in 62 patients who underwent angiography due to peripheral vascular disease.

RESULTS

Intrastenotic peak systolic velocity (PSV) divided by proximally recorded PSV (peak velocity ratio, PVR) exhibited a strong correlation with percent diameter reduction: r2 = 0.86; N = 106 stenoses. A PVR value > or = 2.4 indicated a more than 50% stenosis with a sensitivity of 87% and a specificity of 94%. Calculation of PVR may normalize for patient variation and allow noninvasive quantification of lumen narrowing with high sensitivity and specificity. The intraobserver variability (95% CI) of stenosis quantification using PVR values was 10%. A nomogram simplifies estimation of lumen narrowing after measurement of intrastenotic and proximal PSV values.

CONCLUSION

Quantification of peripheral artery stenoses can be performed easily and noninvasively with duplex ultrasound using the peak velocity ratio (PVR).

Three genes and two isozymes: gene conversion and the compartmentalization and expression of the phosphoglycerate kinases of Trypanosoma (Nannomonas) congolense

The glycosome, a microbody organelle found only in kinetoplastid protozoa, compartmentalizes the first six enzymes of glycolysis. In order to better understand the regulation and targeting of glycolytic enzymes in trypanosomes, we have cloned and analyzed the three genes of the phosphoglycerate kinase (PGK) complex of Trypanosoma (Nannomonas) congolense. The organization of the genes within the complex is similar to that of Trypanosoma brucei brucei. The nucleotide and amino-acid sequences, including those of the novel high-molecular-weight 56PGK, show substantial cross-species similarity. However, the two downstream genes, c1PGK and c2PGK, encode identical isozymes in T. congolense, while they encode distinct glycosomal and cytoplasmic isozymes in T. brucei. Western analysis also indicated that there are only two isozymes in T. congolense and that these are constitutively expressed. Differential digitonin solubilization of the trypanosomes indicated that 56PGK is primarily localized to the glycosome, as expected, and that c1/c2PGK is cytoplasmic. Northern analysis demonstrates that while 56PGK is constitutively expressed, c1PGK and c2PGK mRNAs are differentially expressed in the T. congolense developmental stages. This work demonstrates that T. congolense has only one PGK isozyme, 56PGK, that is predominantly localized in glycosomes.

Effects of resistance exercise on glucose tolerance in normal and glucose-intolerant subjects

This study was conducted to determine whether improvements in glucose tolerance could be observed after a single bout of resistance exercise in young (27.1 +/- 1.24 yr) control subjects, older (53.3 +/- 1.7 yr) patients with non-insulin-dependent diabetes mellitus (NIDDM), and older (50.7 +/- 1.9 yr) age-matched control subjects. Each subject was screened for fitness level and any contraindications to exercise before inclusion in the study. A 75-g oral glucose tolerance test was administered 2 wk after the subjects were screened, and the subjects were familiarized with the exercise equipment. The maximum weight that could be lifted with one repetition was determined on seven Nautilus machines that utilized the upper and lower body. After a 48-h rest period, a 3-set x 10-repetition protocol based on the subject's one repetition maximum was completed by each participant on each machine. Eighteen hours after the lifting protocol, a second oral glucose tolerance test was administered. There was no change in the pre- to post-exercise glucose levels in any of the treatment groups, but the total insulin responses (area under the curve) of the young control and NIDDM groups were significantly lower after exercise: from 6.93 +/- 0.8 x 10(3) to 5.38 +/- 0.65 x 10(3) pM in the young control group and from 9.83 +/- 1.95 x 10(3) to 7.77 +/- 1.50 x 10(3) pM in the NIDDM group. The postexercise C-peptide levels were unchanged in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

L-arginine infusion decreases peripheral arterial resistance and inhibits platelet aggregation in healthy subjects

1. L-Arginine is the physiological precursor of nitric oxide which induces vasodilatation and inhibits platelet aggregation by the formation of cyclic GMP. 2. In the present study we investigated the effects of an intravenous infusion of L-arginine (30 g, 30 min) compared with placebo on blood pressure, heart rate and peripheral haemodynamics in ten healthy male subjects. Cyclic GMP, NO2- and NO3- were determined in plasma and urine to assess NO production in vivo by a new, highly specific and sensitive gas chromatography-mass spectrometry method. 3. L-Arginine significantly decreased mean arterial blood pressure and increased heart rate. The effect was more pronounced on diastolic than on systolic blood pressure. This was due to a decreased peripheral arteriolar resistance, as in femoral artery Doppler sonography the arterial diameter was unchanged but blood flow was increased. These haemodynamic effects were not observed after placebo administration. 4. Urinary excretion of cyclic GMP increased by 65.4% after L-arginine and by 25.1 after placebo. Urinary NO2- excretion was near the threshold of detection. Urinary NO3- excretion increased by 79.7% after L-arginine. Plasma arginine levels increased nearly ten-fold after the L-arginine infusion, and plasma cyclic GMP increased by a similar rate as in urine. However, plasma NO2- and NO3- remained unchanged after both treatments, as did plasma alpha-atrial natriuretic peptide levels. 5. Platelet aggregation was inhibited by 32.7% after L-arginine (P < 0.05), but was unchanged after placebo. Platelet intracellular cyclic GMP was increased by 43.0% after L-arginine, but not after placebo (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal type of thromboangiitis obliterans (Buerger's disease)

Thromboangiitis obliterans (TAO) is a recurrent, inflammatory, segmental occlusive disease of distal limb arteries which may involve veins as well. Young smokers are predisposed to TAO. The intestinal vessels are rarely affected. We report the clinical, angiographic and histologic findings of a 23-year-old smoker with extended thrombophlebitis who developed severe abdominal angina and liver hypoxia due to occlusion of the coeliac artery and subtotal occlusion of the superior mesenteric artery. Two surgical bypassing procedures were followed by early graft occlusion. Subsequently, a plastic patch of the superior mesenteric artery and an aortohepatic bypass were performed. The literature since 1945 pertinent to intestinal TAO is reviewed.

In vivo inhibition of acute platelet-dependent thrombosis in a baboon model by Bay U3405, a thromboxane A2-receptor antagonist

Bay U3405 is a thromboxane A2 (TxA2)-receptor antagonist that inhibits the binding of TxA2 to its target cells. The aim of this study was to determine if Bay U3405 could be used to inhibit arterial thrombosis. A thrombogenic device, consisting of uncrimped Dacron vascular graft material (0.5 cm2) built into the wall of silicone rubber tubing with 4 mm inside diameter, was exposed to native flowing blood under arterial blood flow conditions (100-140 ml/min) by interposing the devices as extension segments into permanent femoral arteriovenous shunts implanted in baboons. Thrombus formation was quantified in vivo by measuring the deposition of 111In-labelled platelets onto the graft material with a scintillation camera. In six baboons, a bolus injection of Bay U3405, calculated to attain an initial plasma concentration of 300 ng/ml, reduced the maximum thrombus formation measured over a 2 h study period. Platelet deposition was reduced by 33 +/- 14% (SD) at 2 h as compared to control studies done in the same baboons. The accumulation of additional platelets onto a thrombus that was allowed to form for 1 h, was reduced by 58 +/- 28% at 2 h. Ex vivo platelet aggregation in response to ADP, activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) were not affected by the treatment. Ex vivo platelet aggregation in response to collagen was markedly inhibited for 2 h after treatment. The results demonstrated that selective blocking of the TxA2-receptor on platelets reduced platelet-dependent thrombus formation and the accumulation of additional platelets in a freshly formed thrombus.(ABSTRACT TRUNCATED AT 250 WORDS)

[Dose-dependent side effects of acetylsalicylic acid therapy. Results of a prospective randomized clinical study in patients with peripheral arterial occlusive disease]

BACKGROUND AND METHODS

In 359 patients with peripheral arterial occlusive disease who had undergone percutaneous transluminal angioplasty (PTA), a randomized double-blind, controlled clinical study was done to investigate the tolerability of acetyl salicylic acid (ASA) given for reocclusion prophylaxis. A comparison was made between a conventional daily dose of 900 mg ASA and a dose of 50 mg ASA.

RESULTS

Within an observation period of one year following PTA, 35 patients (20%) in the 900 mg group, and 32 patients (17%) in the 50 mg group left the trial because of side effects (p = NS). Under the higher dose, however, severe gastrointestinal side effects (ulcer, haemorrhagic gastritis requiring transfusion) were significantly more common (nine patients delta 5.1% vs two patients delta 1.1%, respectively; p = 0.03). Overall, 107 patients (30%) reported subjective side effects such as upper abdominal pain, a sensation of fullness or nausea during the course of the trial. 62 of these patients were from the 900 mg group (35%) as compared with 45 patients (24%) in the 50 mg group (p = 0.02). Self-scoring of epigastric pain on the basis of a visual analogue scale revealed a score of 1.3 (95% confidence interval 0.9 to 1.6) in the 900 mg group and 0.8 (95% confidence interval 0.6 to 1.0) in the 50 mg group. The subjective pain intensity showed a uniform time course for all three types of symptom, with a maximum after three months.

CONCLUSION

Our results confirm the superior tolerability of the lower dose, in particular in elderly patients. For long-term treatment, the smallest possible effective dose should be chosen.

Characterization of a divergent glycosomal microbody phosphoglycerate kinase from Trypanosoma brucei

There are 3 loci in the phosphoglycerate kinase (PGK) gene complex of Trypanosoma brucei. The PGK-A gene product, which we term 56PGK, is targeted to glycosomal microbodies and is highly homologous to the parasite's 2 known PGKs (one cytoplasmic and one glycosomal). However, 56PGK contains an 80 amino acid insertion as well as numerous substitutions compared to the other PGKs. The complementation and kinetic analyses described here demonstrate that 56PGK is an authentic phosphoglycerate kinase--the largest yet described. When expressed in Escherichia coli, 56PGK complements the pgk- phenotype. 56PGK was expressed as a fusion protein and purified to near homogeneity. The Michaelis constants are similar to those of other PGKs, being 0.12 and 2.4 mM for Mg-ATP and 3-phosphoglycerate, respectively. As with other T. brucei PGKs, ATP but not GTP or ITP can serve as a phosphate donor during catalysis. No evidence was obtained for phosphate transfer to atypical substrates. 56PGK shows sulfate inhibition at all concentrations tested, rather than the sulfate activation observed with yeast PGK.

Dose-dependent effect of aspirin on carotid atherosclerosis

BACKGROUND

Antiplatelet treatment with aspirin is well established as secondary prophylaxis after a transient ischemic attack or minor ischemic stroke, but the effect of aspirin treatment on the course of carotid atherosclerosis is unknown. We investigated the effect of aspirin on the initial stages of carotid atherosclerosis.

METHODS AND RESULTS

Patients were recruited from a prospective, randomized, double-blind clinical trial to compare two doses of aspirin (900 mg versus 50 mg daily) with regard to restenoses after lower limb angioplasty. Of the 383 patients admitted to the angioplasty trial, 27 patients with 104 small carotid atheroma (< 50% lumen narrowing) were examined at entry and after 1 year of aspirin treatment with the use of a high-resolution ultrasound duplex system. Disease progression and regression were defined by a change of maximal plaque area (as measured by longitudinal ultrasound sections) of more than 2 SDs of the method. The change in plaque area was significantly different for the treatment groups: Average plaque size remained unchanged after treatment with 900 mg aspirin daily but increased markedly after treatment with 50 mg aspirin daily (p = 0.011). There were significantly more lesions in the 50-mg group showing progression than in the 900-mg group (23 plaques [47%] versus 13 plaques [24%], p = 0.025). Ultrasonic disappearance of a lesion was observed only in the 900-mg group in nine cases (seven soft plaques and two ulcerative plaques, p = 0.018). The six patients on 50 mg aspirin who continued smoking during the study showed significantly more progression compared with the seven nonsmokers in the 50-mg group (17 plaques [59%] versus six plaques [30%], p = 0.038).

CONCLUSIONS

The results of our study indicate that aspirin treatment slows carotid plaque growth in a dose-dependent fashion, with a dose of 900 mg daily more efficient than 50 mg daily.

No ANCA in thromboangiitis obliterans (Bürger's disease)

Sera of 30 patients with clinically well established Thromboangiitis obliterans were tested for the presence of ANCA by means of immunofluorescence and ELISA. ANCA did occur neither in active nor in inactive disease.

Fluorescence energy transfer analysis of calmodulin-peptide complexes

The interactions between calmodulin and the tryptophan residues of synthetic peptides corresponding to the calmodulin binding domains of skeletal muscle myosin light-chain kinase and the plasma membrane calcium pump were examined. The single tryptophan residue contained in each peptide became relatively immobilized and inaccessible to iodide ion upon binding to calmodulin, indicating that the indole side chain was inserted into a hydrophobic cleft in the surface of calmodulin. Fluorescence energy transfer from peptidyl tryptophan residues to an AEDANS moiety attached to cysteine-26 of spinach calmodulin was measured. Included in these analyses was a tryptophan-containing peptide analog of the calmodulin binding domain of neuromodulin. These data indicated that the indole ring of each peptide inserted 32-35 A away from cysteine-26 and may therefore interact with the carboxyl-terminal lobe of CaM in its "bent" conformation [Persechini & Kretsinger (1988a) J. Cardiovasc. Pharmacol. 12 (Suppl 5), S1-S12; Ikura et al. (1992) Science 256, 632-638; Vorherr et al. (1992) Eur. J. Biochem. 204, 931-937]. The interchange of tryptophan-3 and phenylalanine-21 of the calcium pump peptide increased the efficiency of energy transfer to the AEDANS-moiety approximately 12-fold, reducing the calculated distance to 20 A. These data suggest that phenylalanine-21 of the calcium pump peptide interacts with the hydrophobic cleft in the amino-terminal lobe of CaM.

Skin surface oxygen pressure in healthy volunteers and patients with arterial occlusive disease

When measuring transcutaneous oxygen pressure at an electrode core temperature of 37 degrees C autoregulating mechanisms of skin microcirculation can be studied. Because of poor reproducibility of a single PO2 measurement we determined skin surface oxygen pressure fields out of 50 or more PO2 values. At the forefeet and calves of healthy volunteers the histograms were slightly left-shifted with median PO2 of 4 mm Hg. Patients with multilevel arterial occlusive disease and low systolic ankle pressure presented with a disturbed PO2 distribution with very low PO2 values close to zero. About 16% of measurements were above 10 mm Hg. In contrast, diabetics had significantly higher PO2 (median 8 mm Hg) at the forefoot level when compared with healthy volunteers or patients without diabetes.

Intravenous infusion of iloprost in arterial occlusive disease: dose-dependent effects on skin microcirculation

Transcutaneous oxygen pressure (tcPo2), laser Doppler flux and capillary microscopy have been used to examine the forefoot skin in 5 healthy men and 8 patients with severe peripheral arterial occlusive disease in order to evaluate the dose dependent effects of iloprost on skin microcirculation. Iloprost was infused IV starting at 0.0625 ng.kg-1.min-1 and doubling the dose every 15 min up to 2 ng.kg-1.min-1. While tcPo2 at an electrode core temperature of 44 degrees C decreased in both patients and controls, there was a significant dose dependent increase in tcPo2 (37 degrees C) in the controls from 0.25 ng.kg-1.min-1. In the patients the reaction was variable: it was decreased in two and increased in 6, with a maximum either at 0.25-0.5 ng.kg-1.min-1 (n = 3) or at the highest dose (1.0 or 2.0 ng.kg-1.min-1; n = 3). Mean laser Doppler flux in both groups was increased, although the reaction was not consistent in the patients. Density of forefoot skin capillaries was reduced in 3 patients, and in the others the flow velocity was very low. During infusion of iloprost, both an increase in capillary density and blood cell velocity were observed. The effects were of variable intensity and occurred at varying doses, some appeared early and diminished as the dose was increased, and others were found only at 2 ng.kg-1.min-1. Adverse effects were numerous, extending from harmless skin flushing to mental changes and a quickly reversible attack of angina pectoris.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hemodynamic effects of intermittent intra-arterial infusion treatment with prostaglandin E1 in peripheral arterial occlusive disease]

14 femoral arteries of twelve patients with peripheral arterial occlusive disease (Fontaine stage II: n = 4, stage III/IV: n = 10) were investigated before, immediately after a series of 26 (ten to 52) intraarterial infusions with prostaglandin E1, and 30 weeks later. Using combined B-mode and pulsed Doppler (duplex) ultrasound blood flow measurements were performed in the common femoral, the superficial femoral, and the deep femoral artery. There was a significant decrease of resting blood flow volume in the common femoral artery after therapy (418.5----362.2 [p less than 0.01]----324.5 ml/min [p less than 0.05]) in the group of patients treated successfully. The peak flow (maximum value of blood flow volume during reactive hyperaemia) in the common femoral artery increased significantly after therapy (597.3----779.1 [p less than 0.05]----843.7 ml/min). The increase of peak flow correlated well with clinical improvement. Other parameters (blood flow velocities, pulse rise time, pulse decrease time, pulsatility index) changed without correlation to clinical outcome. The increase of peak flow after therapy might be caused by an improved collateral circulation, and the decrease of resting blood flow might be due to metabolic effects of prostaglandin E1 (improved oxygen utilization).

A phosphoglycerate kinase-like molecule localized to glycosomal microbodies: evidence that the topogenic signal is not at the C-terminus

The phosphoglycerate kinase (PGK) gene complex of Trypanosoma brucei contains three tandemly linked related genes. One gene encodes a cytoplasmic PGK, while another encodes a PGK isozyme localized to glycosomal microbodies. In this communication, we report that the third gene in this complex encodes a 56-kDa molecule which is also localized to the glycosomal core. DNA sequence analysis indicates that this gene contains multiple substitutions and a large insertion in the amino domain, but that it is very similar to the other PGK isozymes in the carboxy domain. The C-terminal tripeptide is identical to that of the cytoplasmic isozyme, and only one conservative change occurs in the last 25 amino acids. The encoded protein, p56, thus contrasts with the many peroxisomal microbody proteins in which the C-terminal tripeptide contains sufficient information for targeting to peroxisomes. Multiple mechanisms may exist for targeting proteins to the protein cores of microbody organelles. Comparisons of the DNA sequences of several alleles suggest that homologous recombination plays a role in the generation of allelic diversity.

Alterations of the nailfold capillary morphology associated with Raynaud phenomenon in patients with systemic lupus erythematosus

Quantitative analysis of nailfold capillary morphology was performed in age and sex matched groups of 29 patients with systemic lupus erythematosus (SLE) presenting Raynaud phenomenon (RP), 29 RP negative patients with SLE with the same duration of the disease, and 29 healthy controls. Percentages of tortuous, meandering and bushy capillaries were significantly increased in both groups of patients without influence of RP. Capillary density was lower, mean diameters of the capillary loops were higher in patients, especially when RP was present (at the venular branch in microns, mean +/- SD: controls: 15.0 +/- 2.0, RP negative patients with SLE: 17.6 +/- 3.6, RP positive patients with SLE: 20.5 +/- 6.3). In a subgroup of 13 patients with frequent Raynaud's attacks (more than 1/week), diameters were still higher (22.1 +/- 7.1, p to controls less than 0.0005; p to RP negative patients less than 0.05). In patients with SLE, the prevalence of RP seems not to be associated with the increased number of abnormal capillaries but with capillary enlargement, correlating with the frequency of attacks.

The development of the RISK tool for fall prevention

The authors tailored a 26-item risk assessment tool (RAT) for falls based on a literature review and an analysis of causative factors of falls that had occurred over a 3-month period at the Olin E. Teague VA Medical Center, an 1,100-bed acute medical-surgical, psychiatric, and extended care facility in Temple, TX. The RAT was completed by nursing staff on 10 patient units (four medical, four surgical, and two nursing home units) for all admissions during the period. A 25% sample of the completed RATs was randomly selected (n = 208). Pearson's correlation coefficient was used to identify factors that would most likely predict falls from the RATs of the randomly selected group and of the patients who fell (n = 78). Only 4 of the 26 items were statistically related to falls. Based on findings from this study, the RAT was shortened to the four items and called the RISK (Reassessment Is Safe "Kare") tool.

Microbody phosphoglycerate kinase of Trypanosoma brucei: expression and complementation in Escherichia coli

In the primitive eukaryotic parasite, Trypanosoma brucei, most of the enzymes of glycolysis are located within microbody organelles called glycosomes. Proteins destined for the glycosome are synthesized on free ribosomes and post-translationally translocated into the organelle. The gene, gPGK, encoding the glycosomal isozyme of phosphoglycerate kinase (gPGK), was cloned adjacent to a T7 promoter and cotransformed with a plasmid encoding T7 RNA polymerase into Escherichia coli Pgk-cells. Functional complementation occurred, but only after the creation of a ribosome-binding site by mutagenesis. This represents the first example of complementation of an E. coli mutant with a gene encoding a microbody protein. Enzymatically active recombinant gPGK was purified to near homogeneity by ion exchange chromatography from highly expressing E. coli. The recombinant protein will aid in studies of glycosomal biogenesis.

[Duplex sonography: accuracy, reproducibility and possibilities for error. Checking quantitative flow measurements against an in vitro model]

Using a pulsatile model of tubes, duplex-sonographic measurements of flow were compared with actual flow. The correlation coefficient between actual and duplex-sonographically obtained flow was 0.975, mean percentage deviation being -18.1% (P less than 0.0001). The obvious scatter (margin of error -69.2 to +50%) is to be explained by the simulation closely imitating a real situation: the transducer was hand-held and tubes were placed in muscle or fat tissue. Accuracy was increased by multiple measurements, especially when taking into account only the maximal value of any series of measurements. Vessel diameter was easy to measure accurately (mean error less than 0.01% [-18.7 to +9.4%]). Repeated measurements of flow velocity had only a small scatter (coefficient of variance 0.064). In muscle or fat the Doppler signal was attenuated and the error the greater the deeper the level at which measurements were made. Low flow (common in patients with obstructive vascular disease) can also cause faulty results.

Skin microcirculation and regional peripheral resistance in patients with chronic renal anaemia treated with recombinant human erythropoietin

Skin microcirculation and regional peripheral resistance were studied in 14 patients with renal anaemia during therapy with recombinant human erythropoietin. Haematocrit was raised from 20.0 to 31.3% after 10-12 weeks of treatment and remained stable over another period of 12 weeks. Antihypertensive treatment had to be intensified in five patients. Regional calf blood flow decreased significantly; accordingly, calculated peripheral vascular resistance was increased by more than 100%. However, transcutaneous oxygen pressure (37 degrees C and 44 degrees C) increased significantly. The pathological vasoconstrictor response of skin capillaries was not influenced. There were no significant differences of any parameter between the patients requiring reinforced antihypertensive therapy and those with stable blood pressure. In conclusion skin oxygenation may be improved by erythropoietin treatment to a large extent despite an increase in calculated total limb vascular resistance.

Skin surface oxygen pressure fields during administration of prostaglandin E1 in patients with arterial occlusive disease

Prostaglandin E1 is offered as a new therapeutic agent in the treatment of severe peripheral arterial occlusive disease. Especially when treating patients with ulcers or gangrene, the oxygen tension of the skin should improve during PGE1 administration. The new technique of assessing skin surface oxygen pressure histograms allows study of the skin microcirculation in vivo. Oxygen histograms were determined on the forefeet of 19 patients with different degrees of disease and different occlusion levels before and during a single intraarterial infusion of PGE1 at a dosage of 1.5 ng/kg body weight/min. Only 9 patients showed improvement during the infusion period. Skin oxygen pressure was increased to a large extent only in patients assumed to suffer from diabetic microangiopathy. The effect of a long-term therapy with PGE1 on skin microcirculation remains to be settled.

The inactivation of rhodanese by nitrite and inhibition by other anions in vitro

Cyanide detoxification in mammals occurs, in part, by sulfur transfer by rhodanese to form the less toxic thiocyanate. Thiosulfate and nitrite are often used in combination for the treatment of cyanide intoxication. This report shows that nitrite can inhibit the rate of sulfur transfer by rhodanese in vitro. Nitrate, chloride, sulfate, and acetate were also examined as inhibitors. Inhibition by nitrite appeared to be more complex than for the other anions tested. Closer examination showed that nitrite can inactivate the sulfur-free rhodanese. Our observation leads to the suggestion that, in vivo, either rhodanese is maintained in its more stable sulfur-substituted form or cellular compartmentalization prevents inactivation by nitrite.

Temperature-dependent laser Doppler fluxmetry in healthy and patients with peripheral arterial occlusive disease

Laser Doppler flux (LDF) was determined at the forefoot in 17 healthy volunteers and 16 patients with mild peripheral arterial occlusive disease. LDF was assessed simultaneously by two probes, one was unheated and the other was run with a probe holder temperature of 37 degrees C. During occlusion of the venous circulation a decrease between 43 and 61% was recorded in both groups and at both temperatures. When the leg was elevated there was an increase of about 60% in unheated skin; at 37 degrees C LDF was impaired significantly in patients. During leg dependency LDF decreased in 15 of the volunteers by 44 and 50% which is the result of the physiological vasoconstrictor response. In patients there was a decrease in unheated skin in 12 cases, in heated skin only in 8 cases. When pure oxygen was inhaled, LDF was unchanged in probands, but increased in patients when measured at 37 degrees C. Reactive hyperaemia flow was about three times higher in unheated skin than in heated skin. Reproducibility was best during leg elevation and was more reliable for measurements at 37 degrees C. Rhythmical variations had a frequency of about 4 cycles/min in healthy subjects and 2.6 cycles/min in patients. As a rule, in both groups frequencies at 37 degrees C were higher as compared with unheated skin. Patients had lower frequencies than probands at both temperatures. During intraarterial application of two differently acting drugs quite different reactions of LDF could be recorded. Measurements of LDF at 37 degrees C made differences between patients with PAOD and healthy volunteers more obvious. Moreover, vasomotional changes in skin blood flow could better be studied at this temperature.

Properties of an Escherichia coli rhodanese

A rhodanese enzyme of less than 20,000 molecular weight has been purified from Escherichia coli. The enzyme is accessible to substrates upon addition of whole cells to standard assay mixtures. This rhodanese has a Stokes radius of 17 A which for a globular protein corresponds to a molecular weight close to 14,000. It undergoes autoxidation to a polymeric form which is probably an inert dimer. Enzyme inactivated by oxidation can be reactivated by millimolar concentrations of cysteine. Steady-state initial velocity measurements indicate that the enzyme catalyzes the transfer of sulfane sulfur by way of a double displacement mechanism with formation of a covalent enzyme-sulfur intermediate. The turnover number for the enzyme-catalyzed reaction, with thiosulfate as donor substrate and cyanide ion as the sulfur acceptor, is 260 s-1. This value corresponds to a catalytic efficiency 60% of that measured for a previously characterized bovine liver enzyme of more than twice the molecular weight. Furthermore, KmCN is 24 mM which is 2 orders of magnitude higher than the value observed previously for the bovine enzyme. Evidence from chemical inactivation studies implicates an essential sulfhydryl group in the enzyme activity. It is proposed that this group is the site of substrate-sulfur binding in the obligatory enzyme-sulfur intermediate. Furthermore, a cationic site important for binding of the donor thiosulfate is tentatively identified from anion inhibition studies. Tests of alternate acceptor substrates indicate that the physiological dithiol, dihydrolipoate, is a more efficient acceptor than cyanide ion for the enzyme-bound sulfur. Of possibly greater physiological significance, it has been found that the enzyme catalyzes the formation of iron-sulfur centers. Other work indicates the E. coli rhodanese is subject to catabolite repression and suggests a physiological role for the enzyme in aerobic energy metabolism.

The inhibition of cytochrome oxidase by diaminomaleonitrile

Diaminomaleonitrile, a tetramer of cyanide, was examined as a possible antagonist to cyanide inhibition of cytochrome oxidase (EC 1.9.3.1). This compound was found to inhibit cytochrome oxidase in vitro; however, despite their structural similarities, diaminomaleonitrile and cyanide inhibit cytochrome oxidase by different mechanisms and bind to the enzyme at different sites. Diaminomaleonitrile inhibition of cytochrome oxidase is described in terms of a partially competitive mechanism. Biological oxidation of diaminomaleonitrile may lead to the formation of cyanide.

Comparison of Laser-Doppler-Flux and tcPO2 in healthy probands and patients with arterial ischemia

Transcutaneous PO2 (tcPO2) and Laser-Doppler-Flux (LDF) were compared on the dorsum of the foot in 20 healthy probands and 35 patients with peripheral arterial occlusive disease at clinical stage II b or IV. The probes were kept at a temperature of 37 degrees C. Using different procedures, we brought about dynamic changes and compared the reaction of the two signals. Venous occlusion resulted in a decrease of both signals to a similar extent in both groups. During leg dependency both signals decreased in the probands suggesting a normal vasoconstrictor response. In most of the patients an increase was observed, but some showed a decrease even at clinical stage IV. LDF had a stronger tendency towards a decrease. On leg elevation, LDF slightly increased in probands and decreased in patients. Here, the tendency towards a decrease was higher for tcPO2. After arterial occlusion reactive hyperemia was more pronounced in probands. Differences between tcPO2 and LDF seem to be mainly due to the different capillary systems contributing to the signal.