Bernd Minnich

Architectonic Arrangement of the Vasa Vasorum of the Human Great Saphenous Vein

Objective: The detailed spatial arrangement of the vasa vasorum (VV) of the human great saphenous vein (HGSV) was demonstrated in qualitative and quantitative terms. Materials and Methods: Segments of the HGSV taken from cadavers 12–24 h post mortem and from patients undergoing aortocoronary bypassing were studied by light microscopy of India-ink-injected specimens and by scanning electron microscopy of vascular corrosion casts. Results: Arterial feeders were found to approach the HGSV from nearby arteries every 15 mm forming a rich capillary network within the adventitia and the outer two thirds of the media in normal HGSV, while in HGSV with intimal hyperplasia capillary meshes extended into the inner layers of the media. Within the media, capillary meshes ran circularly. Postcapillary venules drained centrifugally towards the adventitial venous vessels which finally formed venous drainers running adjacent to the arterial feeders. Three-dimensional morphometry of vascular corrosion casts of VV revealed that diameters of (i) arterial VV ranged from 11.6 to 36.6 µm, (ii) capillary VV from 4.7 to 11.6 µm and (iii) venous VV ranged from 11.6 to 200.3 µm. Conclusions: The 3D network of VV suggests these layers are metabolically highly active and therefore require a continuous blood supply. We conclude, therefore, that the VV network must be preserved during in situ bypassing.

Comparison of four near-infrared spectroscopy devices shows that they are only suitable for monitoring cerebral oxygenation trends in preterm infants

Measuring cerebral oxygenation using near‐infrared spectroscopy (NIRS) has taken on an increasingly important role in the field of neonatology. Several companies have already developed commercial devices, and more publications are reporting absolute boundary values or percentiles for neonates. We compared four commercially used devices to discover whether they provided consistent results in the same patients.

Morphological features of vasa vasorum in pathologically changed human great saphenous vein and its tributaries.

BACKGROUND The question whether the primary increase of vasa vasorum (VV) of venous wall (i) plays an initial role in varicogenesis or (ii) is an expression of impairment of the nutritional conditions in superficial veins of lower extremities is not unambiguously solved yet. The aim of the study was to describe the arrangement of the VV within the wall of the human great saphenous vein (GSV) qualitatively, and of its tributaries at different stages of varicosis and in other pathological states like thrombophlebitis or phlebosclerosis. MATERIAL AND METHODS 22 patients deserving an aorto-coronary bypass surgery or GSV surgery were subdivided into three groups according to the staging of their varices and other pathology. The harvested GSV were prepared for light and scanning electron microscopy. One cadaverous specimen of GSV was injected with India ink. RESULTS In specimens from reticular and primary large varices local intimal hyperplasia was regularly found, partially accompanied with a mild increase of VV. Tortuosities and irregular dilations of adventitial veins were also found. In patients with recurrent primary varices or thrombophlebitis severe intimal and medial hyperplasia, thrombosis and a striking increase of VV were found. The intima remained avascular in all cases. CONCLUSIONS Remarkable increase of VV accompanies the most severe forms of varices as well as all cases of the extreme grades of phlebosclerosis, medial hyperplasia and thrombosis. We hypothesize that this increase in VV is rather a secondary vascular reaction to the impaired metabolic conditions within the venous wall than a primary varicogenic factor.

Maturation of the gastric microvasculature in Xenopus laevis (Lissamphibia, Anura) occurs at the transition from the herbivorous to the carnivorous lifestyle, predominantly by intussuceptive microvascular growth (IMG) : a scanning electron microscope study of microvascular corrosion casts and correlative light microscopy

The microvascular bed of the stomach of Xenopus laevis and the changes it undergoes when the herbivorous tadpole becomes a carnivorous adult were studied by scanning electron microscopy of vascular corrosion casts and light microscopy of stained tissue sections. In tadpoles an upper and a lower gastric artery supplied, and upper, middle and lower medial and lateral gastric veins drained the vertically extending stomach. During metamorphosis, the stomach gained a horizontal cranio-caudal extension and vessels accordingly become dorsal and ventral gastric arteries, and anterior, middle and posterior gastric veins, respectively. Up to stage 64 (late climax) mucosal capillaries formed a polygonal network of wide immature-looking capillaries ensheathing gastric glands in a basket-like manner. From stage 64 onwards, blood vessels of the stomach appeared mature, revealed a clear hierarchy and were correlated closely with the histomorphology of the stomach, which had also gained the adult pattern. Within the gastric mucosa, ascending arterioles branched in a fountain-like pattern into wide subepithelial capillaries establishing a centripetal blood flow along the gastric glands, which makes an ultrashort control loop of glandular cells within the branched tubular gastric glands very unlikely. Formation of the stomach external muscular layer started at stage 57 when smooth muscle cells locally formed a single longitudinal and one-to-two single circular layers. Abundant signs of intussusceptive microvascular growth and rare vascular sprouts in vascular corrosion casts indicated that the larval-to-adult microvascular pattern formation of the stomach of Xenopus laevis Daudin occurs predominantly by non-sprouting angiogenesis.

Design of Cerebellar and Nontegmental Rhombencephalic Microvascular Bed in the Sterlet, Acipenser ruthenus : A Scanning Electron Microscope and 3D Morphometry Study of Vascular Corrosion Casts

The design of the microvasculature of cerebellum and nontegmental rhombencephalic areas was studied in eight adult Acipenser ruthenus L. by scanning electron microscopy of vascular corrosion casts and three-dimensional morphometry. Gross vascularization was described and diameters and total branching angles of parent and daughter vessels of randomly selected arterial and capillary bifurcations (respectively, venous mergings) were measured. With diameters ranging from 15.9 +/- 1.9 microm (cerebellum; mean +/- S.D.) to 15.9 +/- 1.7 mm (nontegmental rhombencephalon; mean +/- S.D.) capillaries in Acipenser were significantly (p > or = .05) smaller than in cyclostomes (18-20 microm) but significantly thicker than in higher vertebrates and men (6-8 microm). With the exception of the area ratio beta (i.e., sum of squared daugther diameters divided by squared diameter of parent vessel) of the venular mergings in the nontegmental rhombencephalon, no significant differences (p > or = .05) existed between the two brain areas. Data showed that arteriolar and capillary bifurcations and venular mergings are optimally designed in respect to diameters of parent vessel to daughter vessels and to branching (merging) angles. Quantitative data are discussed both in respect to methodical pitfalls and the optimality principles possibly underlying the design of vascular bifurcations/mergings in selected brain areas of a nonteleost primitive actinopterygian fish.

Blood vessels of the normal and pathologically changed wall of the human vena saphena magna

The vascular supply of the wall of human vena saphena magna was qualitatively studied by the use of several morphological methods on both normal and pathologically changed veins. The material was obtained from patients undergoing aortocoronary bypass or surgery of the varices, and material from cadavers. Under physiological conditions, the wall of vena saphena magna is supplied by delicate system of vasa vasorum, organized in a form of feeding vessels branched into an irregular loose adventitial mesh and continuing further as a microcirculatory network supplying the two outer thirds of the media. Small local dilatations and tortuosities of adventitial veins were found on heavy varicose veins. Slight increase of vasa vasorum growing into the innermost layer of media was detected, but the hyperplastic intima remained avascular. In patients with recurrent varices or with vein thrombophlebitis intimal hyperplasia, degradation of media and thrombosis, were found. Apparent massive increase of vasa vasorum growing into the whole media, hyperplastic intima and into the organizing thrombi, were regularly observed. The increase of vasa vasorum is a part of the complex of pathophysiological reactions of the vein wall on the hypoxia developing during the most serious pathological changes, and not as the primary varicogenic factor. The vascular supply of the wall of the human vena saphena magna was qualitatively studied by the use of several morphological methods on both normal and pathologically changed veins. The material was obtained from patients undergoing aortocoronary bypass grafting or surgery of varices, as well as materials from cadavers. Under physiological conditions the wall of vena saphena magna is supplied by a delicate system of vasa vasorum. It is organized in a form of feeding vessels branched into an irregular loose adventitial mesh, which continues further as a microcirculatory network supplying the outer two thirds of the media. Small local dilatations and tortuosities of adventitial veins were found on severe varicose veins. A slight increase of the vasa vasorum growing into the innermost layer of media was detected, but the hyperplastic intima remained avascular. In patients with recurrent varices or vein thrombophlebitis, intimal hyperplasia, degradation of media and thrombosis, were found. It was regularly observed that there was an apparent, massive increase of the vasa vasorum growing into the entire media, hyperplastic intima, and into the organizing thrombi. The increase of the vasa vasorum is due to the pathophysiological reaction of the vein wall as a result of hypoxia, which develops during the most serious pathological changes. The increase is not the primary varicogenic factor.

Janus-Faced Neutrophil Extracellular Traps in Periodontitis

Periodontitis is characterized by PMN infiltration and formation of neutrophil extracellular traps (NETs). However, their functional role for periodontal health remains complex and partially understood. The main function of NETs appears to be evacuation of dental plaque pathogen-associated molecular patterns. The inability to produce NETs is concomitant with aggressive periodontitis. But in cases with exaggerated NET production, NETs are unable to maintain periodontal health and bystander damages occur. This pathology can be also demonstrated in animal models using lipopolysaccharide as PMN activator. The progress of periodontitis appears to be a consequence of the formation of gingival pockets obstructing the evacuation of both pathogen-associated and damage-associated molecular patterns, which are responsible for the self-perpetuation of inflammation. Thus, besides the pathogenic effects of the periodontal bacteria, the dysregulation of PMN activation appears to play a main role in the periodontal pathology. Consequently, modulation of PMN activation might be a useful approach to periodontal therapy.

Heart rate variability can't be used to evaluate acute distress in preterm infants

Preterm infants are exposed to various potentially stressful procedures during intensive care, which have been shown to compromise development. We explored the potential stress caused by echocardiography and the correlation between the duration of the investigation and the amplitude of the alteration. The usefulness of the Newborn Infant Parasympathetic Evaluation (NIPE) monitor (Mdoloris Medical Systems, Loos, France) for assessing acute distress during daily routines, based on heart rate variability, was also investigated. We recruited 16 preterm infants born before 32 weeks of gestation or weighing less than 1500 g. Their mean gestational age at birth was 29 weeks and four days with a standard deviation (SD) of two weeks and two days, and their mean birthweight was 1183 g (SD 310 g). The infants underwent echocardiography at a mean age of 75 hours (SD 15 hours) for a mean duration of 10 minutes (SD 4 minutes). The NIPE index, heart rate and transcutaneous oxygen saturation (SpO2) were collected and classified into three periods – baseline, during and after echocardiography – for the statistical analysis. The NIPE index increased from baseline (56.82 of 100) to the echo period by a mean of 3.49, median of 3.78 and SD of 9.08, with higher values indicating greater wellbeing and lower stress. The heart rate increased from baseline (152.93 beats per minute) to the echo period at an average rate of 4.67 (3.11%), with a median increase of 3.78 (SD 9.08) and SpO2 decreased from 94.49% at baseline at an average rate of 0.27%, with a median decrease of 0.11% (SD 2.53%). The increase of heart rate and the decrease of SpO2 during echocardiography indicated higher stress levels. There was no correlation between the changes in physiological data and the duration of the examination. Each Pearson r was below 0.1. Heart rate and SpO2 are well-known markers of distress (1), and increased heart rate and decreased SpO2 indicated that the infants were stressed by routine echocardiography. The level of distress was independent of the duration of the intervention. Furthermore, the study demonstrated that the NIPE monitor was not suitable for recording acute discomfort in preterm infants, because its results were not supported by the heart rate and SpO2 results. One possible reason is that preterm infants have an immature nervous system, and their heart rate variability differs from term-born neonates (2). In addition, the NIPE index is based on high-frequency heart rate variability power, which is not always reliable for acute pain assessment (3). The NIPE monitors capability to assess long-term wellbeing was not explored by this study. ACKNOWLEDGEMENT We are grateful to Connect Medizintechnik for providing a NIPE monitor for this study.

Microvascularization of the spleen in larval and adult Xenopus laevis: Histomorphology and scanning electron microscopy of vascular corrosion casts

Microvascular anatomy and histomorphology of larval and adult spleens of the Clawed Toad, Xenopus laevis were studied by light microscopy of paraplast embedded serial tissue sections and scanning electron microscopy (SEM) of vascular corrosion casts (VCCs). Histology showed i) that white and red pulp are present at the onset of metamorphic climax (stage 57) and ii) that splenic vessels penetrated deeply into the splenic parenchyma at the height of metamorphic climax (stage 64). Scanning electron microscopy of VCCs demonstrated gross arterial supply and venous drainage, splenic microvascular patterns as well as the structure of the interstitial (extravasal) spaces representing the “open circulation routes.” These spaces identified themselves as interconnected resin masses of two distinct forms, namely “broccoli‐shaped” forms and highly interconnected small resin structures. Arterial and venous trees were clearly identified, as were transitions from capillaries to interstitial spaces and from interstitial spaces to pulp venules. Venous sinuses were not diagnosed (nonsinusal spleen). The splenic circulation in Xenopus laevis is “open.” It is hypothesized that red blood cells circulate via splenic artery, central arteries, penicillar arteries, and red pulp capillaries primarily via “broccoli‐shaped” interstitial spaces, pulp venules and veins into subcapsular veins to splenic veins while lymphocytes circulate also via the interstitial spaces represented by the highly interconnected small resin structures in vascular corrosion casts. In physiological terms, the former most likely represent the fast route for blood circulation, while the latter represent the slow route. J. Morphol. 277:1559–1569, 2016.

Microvascularization and Histomorphology of Lateral Line Organs in Adult Xenopus laevis

The microvasculariaztion of the lateral line organs (LLOs) of the adult pipid frog, Xenopus laevis was studied by scanning electron microscopy of vascular corrosion casts (VCCs) and correlative light microscopy of paraplast embedded tissues sections. Scanning electron micrographs of VCCs revealed that each neuromast within the LLO rests on a distinct bowl‐like capillary network (vascular bowl). One to three vascular bowls were supplied by an ascending arteriole and drained by a descending venule towards the skin deep dermal vascular network. Blood flow regulation mechanisms in form of intimal cushions were present at the origin of ascending arterioles supplying LLOs, microvenous valves were present at the confluence of deep dermal venules and veins. This together with sprouting and nonsprouting angiogenesis (intussusceptive microvascular growth) found in vascular bowls demonstrate that in adult Xenopus the capillary bed of LLOs still can be adjusted to changing energetic needs. J. Morphol. 275:497–503, 2014.