Severe hyperglycemia: a determinant factor for hypofiltration in alloxan diabetic rats

Abstract. The relationships among glomerular filtration rate, renal plasma flow and extracellular fluid volume were investigated in control and severely hyperglycemic (442±33 mg/dl) untreated, alloxan diabetc rats. Most of diabetic animals showed significant lower values of inulin clearance (diabetics, 0.55±0.07 ml/min·100 g; controls, 0.97±0.04) and p-aminohippurate clearance (diabetics, 2.11±0.39 ml/min·100 g; controls, 3.93±0.25). Diabetic rats exhibited reduced efficiency in tubular Na⁺ reabsorption, increased urinary Na⁺ excretion (diabetics, 3.12±0.27 mEq/day; controls, 1.25±0.14) and diminished values of plasma renin activity (diabetics, 3.34±0.44 ng/ml·h; controls, 8.64±0.79). Significant negative correlations were found between glycemia and renal hemodynamic variables. Acute overload with glucose further decreased these variables in both groups: inulin clearance in diabetics vs. controls, 0.26±0.04 vs. 0.44±0.05 ml/min·100 g; p-aminohippuric acid clearance in diabetics vs. controls, 1.09±0.20 vs. 1.55±0.21 ml/min·100 g. We conclude that chronically hyperglycemic alloxan diabetic rats showed diminished glomerular filtration rates (inulin clearance), renal plasma flow (p-aminohippurate clearance) and extracellular fluid volume associated with urinary Na⁺ losses and alterations in the renin-angiotensin system. Decreased reninangiotensin system activity might reduce aldosterone secretion, which in turn could result in (succesively) urinary sodium loss, extracellular fluid volume contraction and reductions in glomerular filtration and renal plasma flow.     

Acceleration of plague outbreaks in the second pandemic

Historical records reveal the temporal patterns of a sequence of plague epidemics in London, United Kingdom, from the 14th to 17th centuries. Analysis of these records shows that later epidemics spread significantly faster (“accelerated”). Between the Black Death of 1348 and the later epidemics that culminated with the Great Plague of 1665, we estimate that the epidemic growth rate increased fourfold. Currently available data do not provide enough information to infer the mode of plague transmission in any given epidemic; nevertheless, order-of-magnitude estimates of epidemic parameters suggest that the observed slow growth rates in the 14th century are inconsistent with direct (pneumonic) transmission. We discuss the potential roles of demographic and ecological factors, such as climate change or human or rat population density, in driving the observed acceleration.

Plague epidemics have afflicted human populations since at least the sixth century (1, 2). These events have had dramatic and long-lasting effects on human demography and behavior, especially those outbreaks associated with the second pandemic (14th to 19th centuries) in Europe and Asia (1, 3–5), and have inspired many theoretical studies of the ecology and evolution of infectious disease (6–13). We are now in the third pandemic (Modern Plague), with outbreaks continuing to occur in some parts of the world (14–18). Plague also remains a source of concern due to the bioterror potential of the causative agent, Yersinia pestis (19, 20).Recent advances in paleogenomics have definitively established that historical plague pandemics were caused by Y. pestis (21, 22), as proposed in the 19th century after Yersin discovered the bacterium’s link to bubonic plague (23). Researchers have reconstructed the evolutionary history of plague and other pathogens by sequencing and reconstructing nearly complete pathogen genomes from persistent DNA fragments (21, 24, 25). The strain isolated from victims of the Black Death (London 1348) is remarkably similar to extant human strains (Modern Plague): the core genomes^*of these strains are ≈99.99% similar (21), which makes it challenging to identify important evolutionary or ecological patterns from genomic investigations alone. Here we complement genetic studies by exploring more traditional (historical, demographic, and epidemiological) sources of information from a 300-y span of plague outbreaks in the same location (London), revealing a striking change in plague transmission dynamics over the course of the Renaissance period, namely, a fourfold increase in the initial growth rate of outbreaks.We quantify this change without making any assumptions about the underlying transmission processes, exploiting methodology that we have developed previously for this purpose (26). We then consider how this inference can contribute to the debate concerning whether plague transmission was primarily indirect (via rat fleas) or direct (pneumonic human-to- human). We argue that strictly pneumonic transmission in the 14th century is implausible but that beyond this the best that can be done at present is to highlight the biological complexities and uncertainties that limit the potential for further inferences.     

Salivary glands and the aging process: mechanistic aspects, health-status and medicinal-efficacy monitoring

Xerostomia is a major complaint of many elderly individuals, and although they seek medical help, it usually provides no adequate relief. This complaint is considered a major clinical problem, since not less than 25% to 50%-60% of the population over the age of 65 complain of xerostomia. By definition, Xerostomia is a subjective feeling and in up to one-third of the cases does not reflect a real reduction in salivary flow rate but rather the subjective feeling of a dry mouth. Moreover, only a minute portion of the patients suffer from xerostomia with a known aetiology such as radiotherapy or Sjögren's syndrome, while in the majority of the cases, the aetiology is assumed to be related to age, disease, various medications and drugs or is simply idiopathic. The current review focuses on age-related histological, sialometrical and sialochemical changes and on the possible mechanisms which underlie these changes. Finally, directions for further exploring the subject are suggested.     

Effects of aerobic or resistance exercise training on cardiovascular autonomic function of subjects with type 2 diabetes: A pilot study

Background and aims

Both aerobic (AER) and resistance (RES) training improve metabolic control in patients with type 2 diabetes (T2DM). However, information on the effects of these training modalities on cardiovascular autonomic control is limited. Our aim was to compare the effects of AER and RES training on cardiovascular autonomic function in these subjects.

Prediction of unexpected sudden death among healthy dogs by a novel marker of autonomic neural activity

BACKGROUND: Unexpected sudden death among apparently healthy individuals remains a daunting problem. We have previously shown that autonomic modulation of cardiac arrhythmias and autonomic markers, such as baroreflex sensitivity (BRS) and heart rate variability (HRV), carry predictive power after myocardial infarction. OBJECTIVE: We tested the hypothesis that a parameter combining BRS and HRV could predict risk for ventricular fibrillation (VF) during a first ischemic episode in otherwise healthy dogs. METHODS: In 43 fully instrumented dogs, BRS and frequency domain analysis of HRV were determined, as well as the occurrence (n = 10, high-risk) or absence (n = 33, low-risk) of VF during 2 minutes of myocardial ischemia superimposed on submaximal exercise. TARVA (Tonic and Reflex Vagal Activity), expressed in units, is the parameter resulting from the multiplication of BRS by HF/LF (an index of tonic vagal activity). RESULTS: High-risk dogs had markedly lower TARVA values, reflecting lower cardiac vagal activity, than low-risk animals (12 +/- 5 versus 56 +/- 43 units, P < .001). The area under the receiver-operator characteristic curve for TARVA was 0.96 (95% confidence interval 0.86 to 0.99); its optimal cutoff had a 100% sensitivity and a 88% specificity with positive and negative predictive values of 71% and 100%, respectively. CONCLUSION: Differences in cardiac autonomic activity, present in healthy dogs, allow prediction of arrhythmic risk during a first ischemic episode. Increased risk is associated with reduced vagal activity. If confirmed in humans, this finding would open the way to the identification of those apparently healthy subjects at risk for sudden cardiac death during their first episode of myocardial ischemia.     

Wolbachia infection status and genetic structure in natural populations of Polytremis nascens (Lepidoptera: Hesperiidae)

The maternally inherited obligate bacteria Wolbachia is known for infecting the reproductive tissues of a wide range of arthropods. In this study, we surveyed Wolbachia infections in Polytremis nascens (Lepidoptera: Hesperiidae) from 14 locations in China by amplifying the 16S rRNA gene with a nested PCR method and revealed the effect of Wolbachia on host mitochondrial DNA. The results show that 31% (21/67) are Wolbachia positive among all specimens and mainly prevails in southern populations in China. No significant difference in the prevalence is found between the sexes. Notably, the nucleotide diversity of Wolbachia infected butterflies is smaller compared to that of uninfected butterflies. The mitochondrial DNA of infected group appear to be not evolving neutrally (Tajima’s D value = −2.3303 and Fu’s F values = −3.7068). The analysis of molecular variance shows significant differentiation of mitochondrial haplotypes between infected and uninfected specimens (FST = 0.6064). The mismatch analysis speculated the different expansion pattern in Wolbachia infected specimens and all P. nascens specimens. These results suggest that the populations of P. nascens may have recently been subjected to a Wolbachia-induced sweep. Additionally, phylogenetic analysis differentiated the mitochondrial haplotypes of P. nascens into three major clades. The clades are in perfect agreement with the pattern of Wolbachia infection. One of the clades grouped with the butterflies infected with Wolbachia. The remaining two clades grouped with uninfected butterflies from the central-west of China populations and Eastern and Southern China populations respectively, which are isolated mainly by the Yangtze River. The analysis of haplotype networks, geographic distribution and population size change shows that Haplotype 1 in central-west of China is the ancestral haplotype and the populations of P. nascens are expanded.     

龙胆紫染色用于分析精子存活率的方法学研究

目的:探讨龙胆紫染色区分存活精子和死亡精子可能性,以提供一种判定精子存活率的新方法,为男性精液检测和质量评价提供依据。方法:采用不同浓度的龙胆紫溶液对精液样本染色,在光学显微镜下观察染色结果,讨论区分存活精子和死亡精子的标准,并计数一定数量的总精子数,计算存活率,并将计算结果与标准方法比较。结果:经过龙胆紫溶液(0.05%,M/V)染色后在显微镜下存活精子呈现淡蓝色,而死亡精子呈现深紫色,计算获得的存活率与伊红染色法(0.5%,M/V)的结果比较差异统计学意义(t=0.862,双侧P=0.403)。结论:一定浓度的龙胆紫染色后能够清楚地区分存活精子和死亡精子,该法获得的精子存活率结果可靠,龙胆紫染色法可以作为一种新的分析精子存活率的方法。