Comparison of sublingual microcirculatory parameters measured by sidestream darkfield videomicroscopy in anesthetized pigs and adult humans

Background:This study aimed to compare sublingual microcirculatory parameters between anesthetized pigs and conscious adult humans using sidestream darkfield videomicroscopy.The overarching aim of the work was to validate the pig as an experimental model of changes in microcirculatory function following traumatic haemorrhagic shock and resuscitation.Methods:Fourteen large white pigs and 14 humans were recruited for the study.Sublingual sidestream darkfield videomicroscopy clips were captured in anesthetized pigs and conscious humans.Clips underwent manual analysis in Automated Vascular Analysis 3.2 software.The total vessel density(TVD),perfused vessel density(PVD),proportion of perfused vessels(PPVs)and microvascular flow index(MFI)were quantified.An independent samples t test was used for between species comparison of microcirculatory parameters.Results and Conclusions:Conscious humans had a significantly lower TVD,PVD and MFI than anesthetized pigs.No significant difference in PPVs was observed between the species.Perfusion of the microcirculation is a critical determinant of tissue metabolic function and viability.Whilst it may not be surprising that some inter species differences in the sublingual microcirculatory anatomy were identified between pig and human subjects,it is interesting to report the insignificant difference in PPVs.This direct microcirculatory measure represents a relative change which should hold translatable value across species.We therefore conclude the pig is a suitable model for microcirculatory research and may be a suitable species to investigate changes in microcirculatory perfusion following perturbations in cardiovascular homeostasis,for example during traumatic haemorrhagic shock and resuscitation.

Assessing human sperm morphology： top models, underdogs or biometrics？

The assessment of the percentage of spermatozoa having an ＇ideal＇ morphology using so-called strict method is the method recommended in the latest edition of the World Health Organization （WHO） laboratory manual for semen analysis. This recommendation is a result of the statistical association between ＇ideal＇ sperm morphology and fertility, and of the current general belief that sperm morphology assessment should be used primarily as a fertility tool. The notion of an ＇ideal＇ sperm morphology has persisted despite the very low percentage of such spermatozoa in the semen of fertile men, a subject of intense controversy. The detailed categorization of each abnormal spermatozoon has thus, for a long time, been considered optional and partially redundant, an idea which is reflected in the earlier editions of the WHO manual. However, several recent studies have shown the importance of carefully assessing abnormal sperm morphology for use in the diagnosis ＆infertility, to determine fertility prognosis, and for basic or public health studies. One approach, which combines videomicroscopy and computer vision, and is the only approach able to assess the continuum of sperm biometrics, has been used successfully in several recent clinical, basic and toxicology studies. In summary, the visual assessment of detailed sperm morphology--including the categorization of anomalies allowing arithmetically derived indices of teratozoospermia--and the more modern computer-based approaches, although often considered to be redundant, are in fact complementary. The choice of the most appropriate method depends on the field of investigation （clinical, research, toxicology） and the problem being addressed. Each approach has advantages as well as certain limitations, which will be discussed briefly herein.

Tracking bacterial growth in liquid media and a new bacterial life model

By increasing viscosity of liquid media above 8.4 centipoise （cp） i.e. 0.084 g·cm-1·S-1 individual growth and family formation of Escherichia coli was continuously observed in real-time for up to 6 h. The observations showed primarily unidirectional growth and reproduction of E. coli and suggested more than one reproduction in the observed portion of E. coli life span. A new bacterial life model is proposed: each bacterium has a stable cell polarity that ultimately transforms into two bacteria of different generations; the life cycle of a bacterium can contain more than one reproduction cycle; and the age of a bacterium should be defined by its experienced chronological time. This new bacterial life model differs from the dominant concepts of bacterial life but complies with all basic life principles based on direct observation of macroorganisms.

Spontaneous firing properties of rat medial vestibular nucleus neurons in brain slices by infrared visual patch clamp technique

Domestic application of infrared patch clamp techniques on brain slices is limited.The key of the tech-nique is to prepare high-quality brain slices.The present paper describes the preparation procedure of brainstem slices and the spontaneous firing properties of rat medial vestibular nucleus(MVN)neurons.By infrared differ-ential interference contrast technique,neurons of rat MVN were visualized directly at the depth of 50–100 mm underneath the surface of slices.Firing activities of MVN neurons were recorded by the whole-cell patch clamp technique in artificial cerebrospinal fluid(ACSF)and low Ca^(2+)-high Mg^(2+) fluid.The firing mode was more irregular and depressive in low Ca^(2+)-high Mg2+fluid than in ACSF.According to the averaged waveform of action potentials,cells were classified as the neurons with mono-phasic after-hyperpolarization potential(AHP),and the neurons with biphasic AHP.The resting membrane potential(RMP),input resistance(Rin)and membrane capacitance(Cm)of neurons were recorded and com-pared between groups.With infrared videomicroscopy,patch clamp recordings could be made under direct obser-vation in freshly prepared brainstem slices.The discharge activities of MVN neurons were spontaneous and the fir-ing mode was modulated by extracellular calcium concen-tration.The basic membrane properties of two types of neurons were not significantly different,while the differ-ences in waveform might play a role in the segregation between tonic and kinetic cells.