Close Inverse Relationship Research Articles

What should the optimal target hemoglobin be?

Partial correction of anemia in patients with chronic kidney disease (CKD) improves anemia-related symptoms. However, controversy remains as to whether total correction of anemia provides benefits over and above those afforded by partial correction. There is some evidence showing that normalization of hemoglobin (Hb) concentrations may improve the cardiac hyperdynamic state in CKD patients and reduce the diameter of the left ventricle. Further studies have shown that normalization of Hb improves cognitive function and physical capacities as measured by quality of life (QoL) tests. Large studies have shown that in dialysis patients there is a close inverse relationship between hematocrit (Hct) levels and mortality and morbidity. Moreover, there is evidence suggesting that Hct levels higher than those recommended by European Best Practice Guidelines (EBPG) and the National Kidney Foundation Dialysis Outcome and Quality Initiative (NKF-DOQI provide better outcomes for patients with CKD. However, when Hb concentrations are increased to normal in selected patients with cardiac disease, congestive heart failure, or ischemic cardiopathy, higher mortality rates are evident. Therefore, while the majority of patients with CKD may experience significant benefits when Hb is normalized, it seems prudent to recommend individualized target Hb concentrations for each patient, taking into account factors such as age, sex, employment status, physical activity, and co-morbidities.

Atrophy Of Foot Muscles In Type 1 Diabetic Patients In Relation To Presence And Severity Of Neuropathy

Diabetic patients with neuropathy may develop motor dysfunction. In a previous study we found atrophy of the ankle extensors and flexors in neuropathic patients being more pronounced distally. This indicates that evaluation of the morphology of the foot muscles may be more sensitive for the detection of muscular atrophy in neuropathic patients. In this study we included 23 type 1 diabetic patients with a diabetes duration of 29 years (16–38) (median, range). For comparison, 23 age‐, sex‐, weight‐, and height‐matched control subjects were included. Using magnetic resonance imaging, the muscular morphology of the non‐dominant foot was evaluated in all subjects. Applying stereological techniques on consecutive cross‐sectional magnetic resonance images, the total volume of the foot muscles was determined. In addition, the diabetic patients were assessed clinically with a neuropathy symptom score and a neurological impairment score. Patients were also evaluated with motor nerve conduction studies and quantitative sensory examination. As compared with the healthy controls, the volume of the foot muscles was reduced in the diabetic patients being 117 cm3 (23–209) (median, range) and 166 cm3 (94‐263) (p < 0.005), respectively. In the 8 non‐neuropathic patients, the muscle volume was 106% (70–130) of the matched controls, whereas the 15 neuropathic patients had a muscle volume of only 49% (11–95) of the controls (p < 0.001). Furthermore, there was a close inverse relationship between the neurological impairment score and the total muscle volume (r = −0.81, p < 1*10−5). In conclusion, the volume of the foot muscles is reduced in long‐term type 1 diabetic patients with neuropathy. The muscular atrophy is closely related to the severity of neuropathy. We suggest assessment of the volume of the foot muscles to be a sensitive method for the detection of motor dysfunction in diabetic neuropathy.

Ultrastructure and Phagocytic Activity of Rat Peritoneal Macrophages Exposed to Low Temperatures in Vitro

Hypothermia affects various components of the immune system, leading to impaired immune resistance. To examine the in vitro effect of low temperature on the ultrastructure and phagocytic function of rat peritoneal macrophages, cells were incubated at 4, 10, 24, and 37°C for 60 min. Subsequently, their ultrastructure and capacity to engulf latex particles and generate superoxide anions were evaluated. The results showed a close inverse relationship between incubation temperature and ultrastructural changes, i.e., the lower the temperature, the higher the number of altered cells. In addition, at lower temperatures the number of cells capable of phagocytosis was reduced; the cells engulfed fewer particles per cell and generated less superoxide anions. These findings may be relevant for explaining the increased susceptibility to bacterial infections under hypothermic conditions.

Insulin resistance and insulin pulsatility in essential hypertension.

Studies in normal humans and in patients with type 2 diabetes mellitus have demonstrated a close inverse relationship between peripheral insulin sensitivity and the frequency of short-term insulin secretory pulses in the systemic circulation. Our objective was to study this relationship in essential hypertension. Study of insulin sensitivity and insulin pulse characteristics in hypertensive subjects and normotensive controls using well-established techniques. Twelve subjects with essential hypertension and 12 age- and sex-matched normotensive controls were recruited. Insulin action was measured using the glucose clamp technique combined with isotope dilution methodology. Insulin pulsatility in the peripheral circulation was assessed by sampling every 2 min for 90 min after an overnight fast Pulses were identified using the computer program Pulsar. Insulin sensitivity index (glucose infusion rate/ serum insulin) was lower in the hypertensive patients (P= 0.01) and fasting insulin was increased (P= 0.008) compared to controls. The frequency and amplitude of insulin pulses were similar in the two groups. Insulin pulse frequency and insulin sensitivity were inversely related in the normotensive group (r= -0.68, P= 0.015), but not in the hypertensive group (r= -0.23, P= 0.48). Insulin clearance was reduced in the hypertensive group (P= 0.03), and was inversely related to insulin pulse frequency in the two groups combined (r = -0.51, P= 0.01). Insulin action was not related to insulin pulse frequency in essential hypertension, in contrast to the situation in normal man.

Somatostatin binding sites in the white matter of the developing human brainstem: inverse relationship with the myelination process

The ontogeny of somatostatin binding sites was studied in eight fiber tracts of the human lower brainstem in 18 fetuses and infants aged from 21 weeks postconceptional to 6 months postnatal, and in two adults. The study was performed by means of quantitative autoradiography using [ 125I-Tyr 0,DTrp 8]somatostatin-14 as a radioligand. For all structures examined, the highest densities of binding sites were detected in the younger stages and the density of sites decreased during development. These results reveal the existence of a close inverse relationship between the density of somatostatin receptors and the myelination process in the fiber tracts of the human brainstem.

Peri/intraventricular haemorrhage: a cranial ultrasound study on 5286 neonates

Objective: We launched a prospective cranial ultrasound study at the Department of Obstetrics and Gynaecology of the University of Giessen. In this study we examined the incidence and severity of brain damage in neonates and related them to various obstetrical risk factors. Study design: More than 90% of all neonates born between 1984 and 1988 were included in the study ( n=5286) and were screened by ultrasound for cerebral abnormalities on 5–8 days post-partum. The relation between the incidence of peri/intraventricular haemorrhages (PIVH) and obstetrical risk factors were analyzed by contingency tables. Results: The most frequent abnormality was PIVH (3.6%) of various degrees (grade I–III). Periventricular leucomalacia, porencephalia, subarachnoidal haemorrhages, and hydrocephali were rare (≤0.2%). The incidence of PIVH increased progressively with decreasing gestational age, e.g. from 1.6% at 38–43 weeks up to 50.0% at 24–30 weeks of gestation. A large percentage of babies with PIVH were clinically normal. In immature neonates there was a close inverse relationship between Apgar score at 1, 5 and 10 min and both incidence and severity of PIVH. This was in contrast to findings in mature neonates where a marked increase in the incidence of PIVH was found only with Apgar scores as low as 0–4 points. The relation between the incidence of PIVH and both cardiotocography and arterial cord blood pH was poor, independent of the gestational age. The incidence of PIVH was increased in growth retarded fetuses (pH≤7.29), premature rupture of membranes, fever sub partu and gestosis. It is interesting to note that in mature fetuses there was no difference in the incidence of PIVH between vaginally delivered (0.8%) and sectioned breech presentations (2.1%). In preterms at 35–37 weeks with prolonged labour and secondary cesarean section, the incidence of PIVH was very high (11.2%). Conclusion: From the present study we conclude that the incidence of PIVH especially in immature neonates is highly associated with low Apgar scores at birth. Since the Apgar score reflects the clinical condition and the degree of circulatory centralisation of neonates that is influenced by various ante- and intranatal risk factors, a protective obstetrical management is necessary to reduce the incidence of PIVH in neonates.

Relationship of plasma cholesteryl ester transfer protein to HDL cholesterol. Studies in normotriglyceridemia and moderate hypertriglyceridemia.

To evaluate the independent effect of cholesteryl ester transfer protein (CETP) on HDL concentrations in humans, we measured lipids, lipoproteins, postprandial lipemia after an oral fat load, CETP mass, and the activities of CETP, lipoprotein lipase (LPL), and hepatic lipase in 16 healthy, normotriglyceridemic men and in 23 men with moderate, primary hypertriglyceridemia on an American Heart Association Step I diet. Fasting triglycerides and postprandial lipemia were increased and HDL cholesterol (HDL-C) was decreased in hypertriglyceridemic men compared with control subjects (P < .001). In the normotriglyceridemic group, CETP mass (P < .001) and activity (P < .005) were directly related to LPL activity After statistical adjustment for this close association, no significant relationship of CETP to HDL-C independent of LPL activity could be demonstrated in the normotriglyceridemic subjects. In contrast, CETP was unrelated to LPL activity in the hypertriglyceridemic subjects, but CETP concentrations showed a close inverse relationship to HDL-C (r = -.504, P = .014). Structural equation modeling of the association structures between HDL and fasting and postprandial triglycerides, endothelial lipases, and CETP in both groups indicated that the overall regression models for the two groups differed (P < .05). Specifically, the associations between CETP mass and activity and HDL-C differed between both groups (both P < .01). We conclude that high-normal CETP levels lower HDL-C in nonsmoking, nonobese men with moderate, primary hypertriglyceridemia on a hypolipidemic diet, but not in healthy, normotriglyceridemic men on an unrestricted diet. Thus, variation in CETP plasma concentrations may contribute to the high-triglyceride, low-HDL phenotype.

Genotoxicity of urban air particulate matter: Correlations between mutagenicity data, airborne micropollutants, and meteorological parameters

The mutagenicity of airborne particulate matter was monitored at a site representative of the high traffic density of the city of Rome. Inhalable (less than 10 μm) particles were collected every other day with a high‐volume sampler from November 1990 to April 1991. Mutagenicity of particle extracts was evaluated by the microsuspension procedure with Salmonella typhimurium strain TA98. Mutagenic activities of particle extracts displayed a fourfold variation during the period of sampling, with the lowest values in April (about 600 induced revertants mg‐1), and the highest in February (about 2500 revertants mg‐1). Multivariate statistical analyses on the interrelationships between mutagenicity, micropollutants levels and meteorological parameters highlighted a close inverse relationship between air mutagenicity and ambient temperature. Lower temperatures determined both an increased content of organic matter on air particles, and an increased mutagenicity (on a weight basis) of particle extracts, which was a...

Comparison of the effects of EXP3174, an angiotensin II antagonist and enalaprilat on myocardial infarct size in anaesthetized dogs

1. In order to determine whether the renin-angiotensin system is involved in myocardial ischaemia-reperfusion injury, we investigated and compared the effects on infarct size of two different drugs which interfere with this system, i.e., an angiotensin II (AT1) antagonist, EXP3174, and an angiotensin I-converting enzyme inhibitor (ACEI), enalaprilat in a canine model of ischaemia-reperfusion. 2. EXP3174 (0.1 mg kg-1, i.v. followed by 0.02 mg kg-1 h-1 for 5.5 h) and enalaprilate (0.3 mg kg-1, i.v. followed by 0.06 mg kg-1 h-1 for 5.5 h) were used in doses inducing a similar level of inhibition (87 +/- 4 and 91 +/- 3%, respectively) of the pressor responses to angiotensin I. Control animals received saline. 3. Infarct size and area at risk were quantified by ex vivo dual coronary perfusion with triphenyltetrazolium chloride and monastral blue dye. Regional myocardial blood flows (ischaemic and nonischaemic, endocardial, epicardial) were assessed by the radioactive microsphere technique. 4. Both EXP3174 and enalaprilat induced a decrease in mean arterial blood pressure. However, non significant changes in regional myocardial blood flows, whether ischaemic or nonischaemic, were observed after administration of either the ACEI or the AT1 antagonist. 5. The size of the area at risk was similar in the three groups. By direct comparison, there were no significant differences between infarct sizes in the three groups. Furthermore, there was a close inverse relationship between infarct size and transmural mean collateral blood flow in controls, and none of the treatments altered this correlation. Thus, neither EXP3174 nor enalaprilat limited infarct size. 6. These results indicate that activation of the renin-angiotensin system does not contribute to myocyte death in this canine ischaemia/reperfusion model.

Ca(2+)-dependent fluorescence transients and phosphate metabolism during low-flow ischemia in rat hearts.

To determine whether cytosolic free calcium ([Ca2+]i) rises during low-flow ischemia and to determine the mechanisms responsible for contractile dysfunction, isolated rat hearts were studied during graded reductions of coronary flow. Indo1 fluorescence at 385- and 456-nm wave-lengths (F385/456) was used as an index of [Ca2+]i. 31P-magnetic resonance spectroscopy (MRS) was used to measure free energy of ATP hydrolysis (delta GATP), intracellular pH (pHi), and Pi in parallel experiments to determine whether these factors may be responsible for increasing diastolic [Ca2+]i or altering the [Ca2+]i-pressure relationship. When coronary flow was reduced to 20 and 10% of control, diastolic F385/456 increased by 14 +/- 3 and 39 +/- 5%, respectively. Although developed pressure markedly decreased when coronary flow was reduced, there was no change of the F385/456 transient amplitude (systolic minus diastolic). During low-flow ischemia there was a significant decrease of delta GATP and increase of Pi that may lead to increased [Ca2+]i. Furthermore, there was a close inverse relationship between Pi and developed pressure, suggesting that Pi is an important regulator of contractility.

GROWTH HORMONE INSUFFICIENCY IN TURNER SYNDROME: IS BODY WEIGHT THE KEY FACTOR?

The age related decline in spontaneous growth hormone (GH) secretion has been suggested to cause growth failure in girls with Turner syndrome (TS). We studied 23 girls (mean age: 11.1 yrs with 95% confidence intervals (CI) 9.9 to 12.3) diagnosed to have Turner syndrome by karyotype analysis. 15 prepubertal age-matched subjects (mean age: 11.6 yrs with CI 10.4 to 12.8) with growth retardation due to familial short stature and/or constitutional growth delay were chosen as controls. Spontaneous 12-hour nocturnal GH secretion was assessed by RIA at 30 minutes intervals. Plasma IGF-1 levels were determined by RIA after acid-ethanol extraction. In TS, the percentage of ideal body weight was significantly higher than controls (mean: 127.5 with CI 116 to 139 in TS, and 100.3 with CI 96 to 104.5 in controls; P = 0.0005), and correlated with bone age (r= 0.62, P < 0.005). Spontaneous GH secretion was significantly lower in TS than controls (mean: 3.2 ng/ml with CI 2.5 to 3.9 in TS, and 5.4 ng/ml with CI 4.8 to 6.0 in controls; P < 0.0001). No significant difference was found in IGF-1 levels. In controls, GH concentrations correlated with bone age (r= 0.56, P < 0.05), whereas in TS no correlation was found. Interestingly, in TS GH levels negatively correlaled with percentage of ideal body weight (r= - 0.43, P < 0.05). Our results, confirming that obesity is a common finding in girls with TS, at least in the age range of our patients, suggest that overweight might be the key factor in determining the subnormal spontaneous GH secretion. On the basis of our previous observations showing a close inverse relationship between body weight and serum IGFBP-1 levels in TS, it might be hypothesized that obesity, probably by increasing insulin secretion, would reduce IGFBP-1 levels eventually leading to an enhancement of IGF negative feed-back effect on GH secretion.

Nitrogen fixation in chickpea. I. Influence of prior cropping or fallow, nitrogen fertilizer and tillage

N fixation was measured in chickpea in a field experiment on the Darling Downs, Queensland. The 15N natural abundance method was used with barley as a non-fixing control crop. Chickpea was grown with 0, 50 and 100 kg/ha of applied N after pretreatments of either fallow or grain sorghum where sorghum stubble was either incorporated by cultivation, removed or retained on the surface with zero tillage. When chickpea was grown after sorghum both the percentage and amount of N in the tops derived from fixation were larger than after fallow. N fertilizer additions reduced per cent but not total N2fixation. Stubble management had no influence on total N2 fixed. There was a close inverse relationship (R2 = 0.95) between soil nitrate measured at establishment of chickpea and per cent of N derived from fixation. All treatment differences in per cent Nz fixation whether due to prior cropping, fallowing, N fertilizer or tillage could be explained through treatment influences on soil nitrate. Chickpea that had a plentiful supply of soil mineral N for growth accumulated significantly more plant N than plants dependent on N2 fixation. Chickpea grain yields were, however, unaffected by the source or quantity of plant N accumulated. Chickpea provided a positive soil N balance at high fixation rates and a negative balance at low fixation rates.

Reconsolidation of a Torrertic Paleustoll after Tillage with a Paratill

Paleustolls in the USA occur mainly in the central and southern Great Plains. Torrertic Paleustolls are extensive in the southern Great Plains, where Pullman (fine, mixed thermic Torrertic Paleustoll) is the dominant series. Pullman soils occur on ≈ 1.54 million ha. They have dense Bt1 and Bt2 horizons that are slowly permeable and restrict root penetration. Deep soil loosening can enhance water infiltration and root penetration, but surface residues should be retained for further water conservation purposes. These goals can be achieved by using one of several deep chisel, subsoiler, or Paratill implements. A Paratill is a slant-legged implement that loosens a soil without inverting it. Paratill (PT) treatments were imposed on different notillage areas of Pullman soil in 1987, 1988, 1989, and 1990 at shallow (0.15–0.20m) and deep (0.25–0.30m) depths. Sweep tillage to a 7− to 10 − cm depth and no-tillage were other treatments. A given area received the Paratill and sweep tillage treatments only once in the 4-yr period. After imposing the treatments, no-tillage was uniformly used on all areas. In May and December 1990, bulk density (Db) was determined to 0.60 − m depths in all plots. Penetration resistance (PR) and water content were determined in May 1991. Deep PT resulted in the lowest mean Db, but there was no definite trend indicating that time since performing PT had an effect on the results. The PR results were similar to the Db results, and there was not a close inverse relationship between soil water content and PR. Based on this study, the rate of return of Pullman soil to its original condition following PT cannot be predicted.

Insulin-Like Growth Factor Binding Protein 1 (IGFBP-1) Levels in Turner Syndrome

We tested whether IGFBP-1, a modulator of IGF-I action, would play a role in the pathogenesis of growth failure and metabolic picture of Turner syndrome. Fasting serum levels of IGFBP-1 were assessed in nineteen girls with Turner syndrome (aging 6.5 to 17.2 years) by radioimmunoassay. Our patients showed normal values of IGFBP-1 (mean +/- SD: 68.6 +/- 32.5 micrograms/l, range: 16 to 134 micrograms/l; range for age and pubertal stage-matched normal children: 15 to 180 micrograms/l). IGFBP-1 levels inversely correlated with bone age (p < 0.05), weight (p < 0.001), percentage of ideal body weight (p < 0.002) and body mass index (BMI) (p < 0.001). Our results seem to rule out a role of IGFBP-1 in the pathogenesis of growth failure in Turner syndrome. The close inverse relationship between IGFBP-1 levels and BMI suggests the serum concentrations of IGFBP-1 to be regulated by the nutritional status. Due to IGFBP-1 inhibiting action on IGF biological activity, the reduction of IGFBP-1 levels in overweight subjects might represent a mechanism to enhance the IGF insulin-like activity, thus supplementing the insulin action.

Drug resistance of Mycobacterium tuberculosis in Korea

Drug resistance of Mycobacterium tuberculosis has been investigated with isolates from patients screened from a sample population of the nationwide tuberculosis prevalence surveys or from routine cultures. The results showed a close inverse relationship between the prevalence of drug resistance and the efficiency of the past or current National Tuberculosis Control Program (NTP) treatment regimens. Individual drug resistance also showed a close relationship with the extent of use of the relevant drugs. Drug resistance was found in 38.0% of M. tuberculosis isolates from patients in the 1965 survey and remained unchanged until it increased to 48.0% in 1980. The resistance prevalence, however, dropped to 25.3% in the 1990 survey. Such a decrease coincided fairly well with a continuous increase of the treatment efficiency (from 60% in 1984 to 77% in 1989) in the 1980s. Initial drug resistance (IR) also showed a similar trend, namely 26.2% in 1965, 23.9% in 1970, 20.1% in 1975, 30.6% in 1980, 17.4% in 1985 and 15.0% in 1990. A higher prevalence of IR was observed among urban patients than rural patients and among young as opposed to old patients.

Role of nitric oxide in local blood flow control in the anaesthetized dog.

Intravenous infusion of NG-nitro-L-arginine methyl ester (L-NAME), a potent inhibitor of nitric oxide (NO) formation from L-arginine, provokes marked rises in arterial blood pressure by increasing peripheral resistance. In order to further evaluate the contribution of basal NO-formation to control of organ blood flow, regional blood flow distribution within the myocardium, kidney and brain areas was assessed using the tracer-microsphere technique in anaesthetized dogs. After L-NAME (20 mg kg-1 i.v.) kidney perfusion was homogeneously reduced by 55% in the entire cortex and the outer medulla. Within the left ventricular myocardium regional blood flow significantly decreased only in subepicardial layers (-12%), whereas within the entire right ventricle regional blood flow was reduced by 19-24%. A close inverse relationship was found between all changes in regional myocardial blood flows observed after L-NAME and the respective control values. No significant changes in regional blood flow in different areas of the brain were detectable after L-NAME. It is concluded that the contribution of basal NO formation varies greatly between different organs and exhibits significant regional differences within the heart. It is possible that local metabolic mechanisms may compensate functionally for the inhibition of NO synthesis.

Risk of cerebral hemorrhage in premature and mature newborn infants

We launched a prospective cranial ultrasound screening study at the Maternity Hospital of the University of Giessen to examine the incidence and severity of brain damage in newborns. More than 90% of all neonates born during 1984-86 were included in the study (n = 2781) and were screened for cerebral abnormalities on 5.9 +/- 3.3 (SD) day post partum. There were in 7.8% sonographic abnormalities, the most frequent being peri/intraventricular haemorrhages (5.2% PIVH of various degrees (grade I-III). Periventricular leucomalacia, porencephalia, subarachnoidal haemorrhages, and hydrocephali were rare (less than or equal to 0.2%). The incidence of PIVH increased progressively with decreasing gestational age, e.g. from 1.5% at 41 weeks up to 61% at 24-30 weeks of gestation. A large percentage of babies with cerebral haemorrhages were clinically normal. There was a close inverse relationship between the Apgar score at 1,5 and 10 min and both incidence and severity of PIVH. However, the relation between PIVH and both cardiotocography (matched-pairs analysis) and arterial cord blood-pH was poor. The incidence of PIVH was increased in growth retarded newborns (pH less than or equal to 7.29), preterm multiples and amnionitis, but not after preeclampsia and premature rupture of membranes. It is interesting to note that, in mature newborns (greater than or equal to 38 weeks), there was no difference in the incidence of PIVH between spontaneous deliveries, vacuum extractions, and Caesarean sections, and that there was no difference between vaginally delivered (1.5%) and sectioned breech presentations (3.5%) in this group. In preterms at 35-37 weeks with protracted labour and secondary Caesarean section, the incidence of PIVH was high (19%). We conclude, that neonatal cranial ultrasound screening is an important tool for risk assessment and quality control in obstetrics. It clearly improves both the quality of the advice given to the patients and the clinical management of high-risk pregnancies.

The ethics of parimutuel systems

One strand of the moral case for the superiority of parimutuel systems of betting over bookmaking emphasises that, as the name implies, the bettors are betting amongst themselves and that there is no discrimination against any individual bettor or groups of bettors. This claim is undermined by three deviations from the pure parimutuel principle found in many systems. Given that there is a close inverse relationship between the income/wealth of bettors and the average odds of the bets they place, the three deviations-higher deductions from long odds ("exotic") pools, higher deductions from pools when longer odds horses win and the paying of minimum dividends-each move a parimutuel system in the unethical direction ofregressive taxation.

Prolonged Bleeding Time of Chediak-Higashi Cats Corrected by Platelet Transfusion

Cats with the Chediak-Higashi syndrome (CHS) have a platelet storage pool deficiency (SPD). Ten CHS cats were transfused with a concentrate of 51Cr-labeled platelets prepared from normal donor cats. One hour after transfusion, the donor platelet count in CHS recipient cats was 40,000-60,000/microliters. Bleeding time before transfusion was 9.1 +/- 3.0 min. When donor platelet count in CHS cats was 50,000/microliters, bleeding time was 1.7 +/- 0.2 min. Bleeding time of normal cats was 1.4 +/- 0.3 min. Bleeding time increased to 3.3 +/- 0.2 min and to 5.3 +/- 0.2 min when the platelet count was 30,000/microliters, and 15,000/microliters, respectively. The close inverse relationship between bleeding time and number of donor platelets in CHS cats (r = -0.92), suggests that prolonged bleeding time is due to a platelet abnormality, that platelet transfusion can effectively correct prolonged bleeding time in an animal model of platelet SPD and that CHS cats may be an appropriate animal model to evaluate hemostatic capabilities of transfused platelets.

Diversity of common beans (Phaseolus vulgaris, Fabaceae) and conditions of production in Aguascalientes, Mexico

This study analyzes the regional diversity of common beans (Phaseolus vulgaris, Fabaceae) in Aguascalientes, Mexico, in relation to local physical, biological, cultural, and socioeconomic factors. A close direct relationship between bean diversity and the physical and biological factors and a close inverse relationship between bean diversity and the cultural and socioeconomic factors was found. Greater bean diversity was found in areas under rainfed conditions with low-input traditional agriculture where farmers with low income cultivate a great number of local heterogeneous landraces to insure some production for home use in spite of environmental stress conditions. Reduced bean diversity is cultivated under irrigated conditions with high-input modern agriculture where farmers with high income grow a few uniform improved cultivars to obtain high yields for commercial purposes. A previous study showed greater morphological variation in the seed collected in the 1940s compared to that collected in 1984. The bean variants of 1984 showed significantly earlier maturation. These findings suggest the necessity of periodic studies for a better understanding of the dynamic process of evolution of beans under continuous ecological, cultural, and socioeconomic change.