Tree-rings stable isotope (δ18O and δ2H) based 368 years long term precipitation reconstruction of South Eastern Kashmir Himalaya

The hydroclimatic variability in Kashmir Himalaya is influenced by the western disturbances and the Indian Summer Monsoon. To investigate long-term hydroclimatic variability, 368 years tree-ring oxygen and hydrogen isotope ratios (δ¹⁸O and δ²H) extending from 1648 to 2015 CE were analysed. These isotopic ratios are calculated using five core samples of Himalayan silver fir (Abies pindrow) collected from the south-eastern region of Kashmir valley. The relationship between the long and short periodicity components of δ¹⁸O and δ²H suggested that physiological processes had a minimum effect on the tree-ring stable isotopes in Kashmir Himalaya. The δ¹⁸O chronology was developed based on the average of five-individual tree-ring δ¹⁸O time series covering the time span of 1648-2015 CE. The climate response analysis revealed the strongest and most significant negative correlation between tree ring δ¹⁸O and precipitation amount from the previous year's December to current year's August (D2A_pre). The reconstructed D2A_pre (D2A_rec) explains precipitation variability from 1671 to 2015 CE and is supported by historical and other proxy-based hydroclimatic records. The reconstruction has two distinguishing features: first, it is characterized by stable wet conditions during the last phase of Little Ice Age (LIA) i.e., from 1682 to 1841 CE; and second, the southeast Kashmir Himalaya had experienced drier conditions as compared to recent and historical period with intense pluvial events since 1850. The present reconstruction shows, there have been more extreme dry events than extreme wet events since 1921. A tele-connection is observed between D2A_rec and Sea Surface Temperature (SST) of the Westerly region.

The modulation of Pacific Decadal Oscillation on ENSO-East Asian summer monsoon relationship over the past half-millennium

Monsoon precipitation affects natural and social systems in East Asia, one of the most densely populated regions in the world. Monsoon precipitation variability is strongly influenced by El Niño-Southern Oscillation (ENSO) and may be related to the phase of the Pacific Decadal Oscillation (PDO). However, a collective understanding of the long-term PDO-ENSO-monsoon relationship remains limited because related studies are almost exclusively based on short instrumental records. Although paleoclimate proxies for PDO and ENSO are currently available, there is a lack of high-quality proxies for East Asian summer monsoon (EASM) precipitation. Moreover, the strengthening of the ENSO-EASM relationship since the 1970s has raised the question of anthropogenic impact. Reconstructing EASM precipitation is thus crucial to understanding its variability under natural and anthropogenic forcings. In this study, we addressed these challenges using tree ring oxygen isotopes of red cypress (Chamaecyparis formosensis Matsum), a long-lived endemic tree species in Taiwan. We developed an annual-resolved and well-validated EASM precipitation proxy from 1533 CE to 2011 which explained 49 % of the variance in instrumental precipitation. In comparison with multiple paleoclimate proxies, we revealed that PDO persistently modulated the ENSO-EASM relationship over the past half-millennium. The ENSO-EASM relationship was enhanced during the positive PDO phases and dynamically weakened during the negative PDO phases, notably in the early-17th, 18th, and early to mid-20th centuries. The strengthened relationship since the 1970s concurred with an unusually high PDO and ENSO and fell within its natural variability. Nevertheless, as the amplitude of the PDO is predicted to weaken under warming, the modulation effects may become less predictable.

Delayed warming in Northeast China: Insights from an annual temperature reconstruction based on tree-ring δ18O

Global warming has had an unprecedented impact on environmental changes and thus human life in mid-high latitude regions. As one of the areas most affected by global warming, Northeast China has suffered from a series of ecological crises, including warming-induced water deficits, permafrost thaw, and extended growing seasons. The change in annual average temperature (annual T) variations in Northeast China since the Industrial Revolution are still not fully understood, mainly because of the lack of long-term instrumental data and high-resolution annual T reconstructions. Here, we present the first annual T reconstruction (r = -0.683, p < .001, n = 60) for 1818-2012 in Northeast China, which may also be the first temperature reconstruction based on tree-ring δ¹⁸O in China. The reconstruction is significantly related to temperature variations over mid-high latitude Eurasia and agree (p < .01) with several long-term hydroclimatic reconstructions in the surrounding area. When the internal variability in the reconstruction was high, the decadal to multidecadal cycles were significant. Further analysis found that the reconstruction was mainly affected by the East Asian Summer Monsoon (EASM) and North Atlantic Oscillation (NAO). The reconstruction was significantly negatively correlated with several time series of annual T in the Northern Hemisphere, which showed that there is a substantial difference in annual T between Northeast China and other regions of the Northern Hemisphere. The difference mainly existed before the 1950s. From the 1850s to the 1950s, the annual T in Northeast China decreased slightly. However, extreme warming began in the 1950s in Northeast China, and this warming has been unprecedented during the past two centuries. If the warming trend since the 1950s continues, then it will lead to devastating disasters to forest and permafrost ecosystems in Northeast China.

A 338-year tree-ring oxygen isotope record from Thai teak captures the variations in the Asian summer monsoon system

A 338-year oxygen isotope record from teak tree-ring cellulose collected from Mae Hong Son province in northwestern Thailand was presented. The tree-ring series preserves the isotopic signal of the regional wet season rainfall and relative humidity. Tree-ring δ¹⁸O correlates strongly with regional rainfall from May to October, showing coherent variations over large areas in Southeast Asia. We reconstructed the summer monsoon season (May to October) rainfall based on a linear regression model that explained 35.2% of the actual rainfall variance. Additionally, we found that in the 19^th century, there was a remarkable drought during many years that corresponded to regional historic drought events. The signals of the June to September Indian summer monsoon (ISM) for the period between 1948 and 2009 were clearly found. Spatial correlations and spectral analyses revealed a strong impact of the El Niño-Southern Oscillation (ENSO) on tree-ring δ¹⁸O. However, ENSO influenced the tree-ring δ¹⁸O more strongly in the 1870-1906, 1907-1943, and 1944-1980 periods than in the 1981-2015 period, which corresponded to periods of weaker and stronger ISM intensity.

Specific response of earlywood and latewood δ18O from the east and west of Mt. Qomolangma to the Indian summer monsoon

This study reports the earlywood and latewood δ¹⁸O time series from two hemlock sites located to the east (EQ) and west (WQ) of Mt. Qomolangma (Everest) in the Himalaya. The latewood δ¹⁸O series from both sites were highly consistent, whereas the earlywood δ¹⁸O values for the two sites show variations over the investigation period. Climate response analysis revealed that the dominant control on latewood δ¹⁸O values at both sites was the precipitation amounts of the middle/peak periods of upstream Indian Summer Monsoon (ISM). However, for EQ- and WQ-Earlywood, the main controls were precipitation amounts during the early and middle phases of the upstream ISM, respectively. The upstream amount effect could have accounted for earlywood and latewood δ¹⁸O variance. Combined with moisture transport models, we found that source water incorporated into latewood at both sites was derived mainly from the Bay of Bengal and Arabian Sea during middle/peak ISM precipitation. However, during the early ISM, the high ridges of Mt. Qomolangma may block most of the moisture that originates from the Bay of Bengal, which results in a stronger signal of early ISM being recorded in EQ-Earlywood δ¹⁸O. The influence of the ISM on WQ-Earlywood is delayed until the middle ISM.

Sampling strategy and climatic implication of tree-ring cellulose oxygen isotopes of Hippophae tibetana and Abies georgei on the southeastern Tibetan Plateau

The tree-ring cellulose oxygen isotopes (δ¹⁸O) for four trees of Hippophae tibetana and four trees of Abies georgei growing in different locations around the terminal moraine in Xincuo from 1951 to 2010 were measured to explore its potential for reconstructing climatic variations in the southeastern Tibetan Plateau. The mean and standard deviation of tree-ring δ¹⁸O at different heights do not have significant differences, and there are no significant differences in the mean and standard deviation of tree-ring δ¹⁸O between trees near the brook and trees at the top of moraine, indicating that we can collect samples for tree-ring δ¹⁸O analysis regardless of sampling heights and that the micro-environment does not affect tree-ring δ¹⁸O significantly. The mean inter-series correlations of cellulose δ¹⁸O for A. georgei/H. tibetana are 0.84/0.93, and the correlation between δ¹⁸O for A. georgei and H. tibetana is 0.92. The good coherence between inter-tree and inter-species cellulose δ¹⁸O demonstrates the possibility of using different species to develop a long chronology. Correlation analysis between tree-ring δ¹⁸O and climate parameters revealed that δ¹⁸O for A. georgei/H. tibetana had negative correlations (r = -0.62/r = -0.69) with relative humidity in July-August, and spatial correlation revealed that δ¹⁸O for A. georgei/H. tibetana reflected the regional Standardized Precipitation Evapotranspiration Index (29°-32° N, 88°-98° E). In addition, tree-ring δ¹⁸O in Xincuo has a significant correlation with tree-ring δ¹⁸O in Bhutan. The results indicate that cellulose δ¹⁸O for A. georgei and H. tibetana in Xincuo is a good proxy for the regional hydroclimate.

Increased drought events in southwest China revealed by tree ring oxygen isotopes and potential role of Indian Ocean Dipole

The highlands in southwestern China experience pronounced fluctuations in the hydroclimate with profound impacts on agriculture and economics. To investigate the drought history of this region beyond instrumental records, a tree ring cellulose oxygen isotope (δ¹⁸O_c) chronology was developed for the period 1733-2013 using samples collected from six Larix trees in the low-latitude highlands (LLH) of southwestern China. The analysis revealed that δ¹⁸O_c is significantly correlated with the rainy season (May-October) precipitation and relative humidity, as well as drought severity. The δ¹⁸O_c chronology accounts for 46% of the observed variance in the rainy season precipitation and it was subsequently used to reconstruct precipitation. The reconstructed precipitation reveals an apparent drying trend since 1840, accompanied by increasingly frequent drought events since 1970. Interdecadal variability is also present, characterized with two distinct wet periods in 1740-1760 and 1800-1900 and two drier periods in 1760-1800 and 1900-2013. On the interannual timescale, the LLH precipitation was modulated collectively by the El Niño-Southern Oscillation (ENSO) and the Indian Ocean dipole (IOD). There appears to be an enhanced precipitation-IOD relationship since 1970 in response to the increase in positive-IOD events, implying an increasing likelihood of drought for the southwest China LLH.

Seasonal changes of δD and δ18O in tree-ring cellulose of Quercus crispula suggest a change in post-photosynthetic processes during earlywood growth

Leaf photosynthetic and post-photosynthetic processes modulate the isotope ratios of tree-ring cellulose. Post-photosynthetic processes, such as the remobilization of stored starch in early spring, are important to understanding the mechanisms of xylem formation in tree stems; however, untangling the isotope ratio signals of photosynthetic and post-photosynthetic processes imprinted on tree rings is difficult. Portions of carbon-bound hydrogen and oxygen atoms are exchanged with medium water during post-photosynthetic processes. We investigated the δD and δ18O values of tree-ring cellulose using Quercus crispula Blume trees in two different habitats to evaluate seasonal changes in the exchange rate (f-value) of hydrogen or oxygen with medium water, and examined the associations of the post-photosynthetic processes. Theoretically, if the f-value is constant, δD and δ18O would be positively correlated due to meteorological factors, while variation in the f-value will create a discrepancy and weak correlation between δD and δ18O due to the exchange of carbon-bound hydrogen and oxygen with medium water. The values of δD decreased drastically from earlywood to latewood, while those of δ18O increased to a peak and then decreased toward the latewood. The estimated seasonal f-value was high at the beginning of earlywood and decreased toward the latewood. The post-photosynthetic processes associated with changes in the f-value were the remobilization of stored starch and triose cycling during cellulose synthesis because of the shortage of photo-assimilates in early spring. Although we did not evaluate relevant physiological parameters, the seasonal pattern of δD and δ18O in tree-ring cellulose of Q. crispula was clear, suggesting that the dual isotope (δD and δ18O) approach can be used to reveal the resource allocation mechanisms underlying seasonal xylem formation.

Evaluation of the effect of the 2011 Tsunami on coastal forests by means of multiple isotopic analyses of tree-rings

The March 2011 Mega-Tsunami in eastern Japan damaged at different degrees the black pine (Pinus thunbergii) forests along the coast. In order to evaluate the recovery of black pine four years later, tree-ring samples from 9 trees for the period 2002-2014 were analyzed for ring growth and stable isotopes (δ¹³C, δ¹⁵N and δ¹⁸O). The results showed that annual tree-ring width decreased approximately 70 % from the year 2011 to 2014 compared to the period previous to the tsunami (2002-2010). The multiple isotopic analyses showed that the reduction in growth was caused by soil salinity that prompted stomatal closure and an abrupt increase of tree-ring δ¹³C. Sea water deposition in the soil did not affect tree-ring δ¹⁸O values. Two years after the tsunami, decreasing tree-ring δ¹³C values caused by apparently photosynthetic recovery did not translate into radial tree-growth, indicating a possible shift in carbon allocation to foliage and mainly roots as a defense mechanism to sodium toxicity. The dual δ¹³C-δ¹⁸O model explains neither the limited growth nor the subsequent recovery in δ¹³C. Similarly tree-ring δ¹⁵N indicated that there was no difference in nitrogen availability before and after the tsunami, suggesting that nutrients were not a limitation but rather soil salinity.

Synaptic modulation of excitatory synaptic transmission by nicotinic acetylcholine receptors in spinal ventral horn neurons

Nicotinic acetylcholine receptors (nAChRs) are distributed widely in the central nervous system and play important roles in higher brain functions, including learning, memory, and recognition. However, functions of the cholinergic system in spinal motoneurons remain poorly understood. In this study, we investigated the actions of presynaptic and postsynaptic nAChRs in spinal ventral horn neurons by performing whole-cell patch-clamp recordings on lumbar slices from male rats. The application of nicotine or acetylcholine generated slow inward currents and increased the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs). Slow inward currents by acetylcholine or nicotine were not inhibited by tetrodotoxin (TTX) or glutamate receptor antagonists. In the presence of TTX, the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs) were also increased by acetylcholine or nicotine. A selective α4β2 nicotinic receptor antagonist, dihydro-β-erythroidine hydrobromide (DhβE), significantly decreased nicotine-induced inward currents without affecting the enhancement of sEPSCs and mEPSCs. In addition, a selective α7 nicotinic receptor antagonist, methyllycaconitine, did not affect either nicotine-induced inward currents or the enhancement of sEPSCs and mEPSCs. These results suggest that α4β2 AChRs are localized at postsynaptic sites in the spinal ventral horn, non-α4β2 and non-α7 nAChRs are located presynaptically, and nAChRs enhance excitatory synaptic transmission in the spinal ventral horn.

Reactive oxygen species enhance excitatory synaptic transmission in rat spinal dorsal horn neurons by activating TRPA1 and TRPV1 channels

Central neuropathic pain (CNP) in the spinal cord, such as chronic pain after spinal cord injury (SCI), is an incurable ailment. However, little is known about the spinal cord mechanisms underlying CNP. Recently, reactive oxygen species (ROS) have been recognized to play an important role in CNP of the spinal cord. However, it is unclear how ROS affect synaptic transmission in the dorsal horn of the spinal cord. To clarify how ROS impact on synaptic transmission, we investigated the effects of ROS on synaptic transmission in rat spinal cord substantia gelatinosa (SG) neurons using whole-cell patch-clamp recordings. Administration of tert-butyl hydroperoxide (t-BOOH), an ROS donor, into the spinal cord markedly increased the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) in SG neurons. This t-BOOH-induced enhancement was not suppressed by the Na(+) channel blocker tetrodotoxin. However, in the presence of a non-N-methyl-D-aspartate glutamate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione, t-BOOH did not generate any sEPSCs. Furthermore, in the presence of a transient receptor potential ankyrin 1 (TRPA1) channel antagonist (HC-030031) or a transient receptor potential vanilloid 1 (TRPV1) channel antagonist (capsazepine or AMG9810), the t-BOOH-induced increase in the frequency of sEPSCs was inhibited. These results indicate that ROS enhance the spontaneous release of glutamate from presynaptic terminals onto SG neurons through TRPA1 and TRPV1 channel activation. Excessive activation of these ion channels by ROS may induce central sensitization in the spinal cord and result in chronic pain such as that following SCI.

Anterior skull base surgery for secondary malignancies in retinoblastoma survivors: report of two cases

With the improved survival rate of patients with retinoblastoma, the incidence of second malignancies has become substantial. We had two retinoblastoma survivors with secondary malignancies in the naso-ethmoidal complex, one a 21-year-old man with anaplastic carcinoma and the other a 16-year-old girl with malignant fibrous histiocytoma. They underwent repeated craniofacial surgery. Secondary malignancies arising at the nose and ethmoidal cells often invade the anterior skull base. The introduction of skull base surgery has provided wider surgical margins and increased the resultant likelihood of cure. Both patients have so far shown no evidence of recurrence.

Proteinase-activated receptor-1 activation presynaptically enhances spontaneous glutamatergic excitatory transmission in adult rat substantia gelatinosa neurons

Proteinase-activated receptors (PARs) have a unique activation mechanism in that a proteolytically exposed N-terminal region acts as a tethered ligand. A potential impact of PAR on sensory processing has not been fully examined yet. Here we report that synthetic peptides with sequences corresponding to PAR ligands enhance glutamatergic excitatory transmission in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole cell patch-clamp technique. The frequency of spontaneous excitatory postsynaptic current (EPSC) was increased by PAR-1 agonist SFLLRN-NH2 (by 47% at 1 microM) with small increases by PAR-2 and -4 agonists (SLIGKV-NH2 and GYPGQV-OH, respectively; at >3 microM); there was no change in its amplitude or in holding current at -70 mV. The PAR-1 peptide action was inhibited by PAR-1 antagonist YFLLRNP-OH. TFLLR-NH2, an agonist which is more selective to PAR-1 than SFLLRN-NH2, dose-dependently increased spontaneous EPSC frequency (EC50=0.32 microM). A similar presynaptic effect was produced by PAR-1 activating proteinase thrombin in a manner sensitive to YFLLRNP-OH. The PAR-1 peptide action was resistant to tetrodotoxin and inhibited in Ca2+-free solution. Primary-afferent monosynaptically evoked EPSC amplitudes were unaffected by PAR-1 agonist. These results indicate that PAR-1 activation increases the spontaneous release of L-glutamate onto SG neurons from nerve terminals in a manner dependent on extracellular Ca2+. Considering that sensory processing within the SG plays a pivotal role in regulating nociceptive transmission to the spinal dorsal horn, the PAR-1-mediated glutamatergic transmission enhancement could be involved in a positive modulation of nociceptive transmission.

Behaviors of the "raman spectroscopic signature of life" in single living fission yeast cells under different nutrient, stress, and atmospheric conditions

Time- and space-resolved Raman spectra of mitochondria in single living fission yeast cells have been measured under various nutrient, stress, and atmospheric conditions. A focus is placed on the behavior of the Raman band located at 1602 cm(-1), which sensitively reflects the metabolic activity in mitochondria and which has been called by us the "Raman spectroscopic signature of life". Addition of nutrients increases the intensity of this band by approximately 1.5 times, confirming its correlation with the metabolic activity in mitochondria. The spectra of cells cultured under 100% N(2), 100% O(2), and N(2)/O(2) (V(N2):V(O2) congruent with approximately = 4:1) atmospheres have been measured for both (16)O(2) and (18)O(2). Yeast cells have been found to lose their metabolic activity after the culture under 100% N(2) and 100% O(2) atmospheres. Cells cultured under a N(2)/(16)O(2) ((16)O(2) = 20%) atmosphere show strong "Raman spectroscopic signature of life". No (18)O isotopic shift has been found for the wavenumber 1602 cm(-1), indicating that the origin of this signature is neither O(2) nor an O-containing small molecule. Addition of H(2)O(2) causes a quick decrease of the "Raman spectroscopic signature of life", followed by the cis-trans isomerization in the unsaturated phospholipid chain. The "Raman spectroscopic signature of life" has thus been proved to be a reliable real-time and in vivo indicator for monitoring the metabolic activity in living cells.

Elastic plasma protein film blended with platelet releasate accelerates healing of diabetic mouse skin wounds

BACKGROUND AND OBJECTIVES

The growth factors derived from platelets and plasma proteins mediate the wound-healing process that is characterized by the sequential migration and differentiation of several cell populations that give rise to angiogenesis, collagen synthesis, wound contraction, and re-epithelialization. To evaluate the efficacy of the blood-derived factors in wound healing, we examined a novel wound dressing consisting of concentrated human plasma proteins and platelet releasate (CPPP).

MATERIALS AND METHODS

To generate CPPP, plasma proteins and platelets in the peripheral blood (n = 5) were concentrated with the cold ethanol precipitation method. The thrombin obtained from the same blood unit and calcium chloride (CaCl(2)) were mixed to a concentrate. The CPPP has enough strength to dress cutaneous wounds and contains large amounts of cytokines and fibronectin. We applied the CPPP to excisional skin wounds in genetically healing-impaired model mice (n= 5) and the wounds were evaluated 10 days after the operation.

RESULTS

The area of CPPP-treated wounds decreased significantly compared with that of the control wounds (65% vs. 94% of the original size, respectively, P= 0.032). The immunostained section revealed a striking effect of CPPP on vascularization compared with the control wounds (13.2 vs. 2.7 vessels per mm(2) as mean vascular density observed in the sections, respectively, P= 0.013).

CONCLUSIONS

Our results suggest that CPPP is a promising biologically active dressing for full-thickness skin wounds. CPPP can be an entirely autologous biological dressing, suggesting that it is free from the risk of transmission of pathogens through blood products.

Tramadol, but not its major metabolite (mono-O-demethyl tramadol) depresses compound action potentials in frog sciatic nerves

BACKGROUND AND PURPOSE

Although tramadol is known to exhibit a local anaesthetic effect, how tramadol exerts this effect is not understood fully.

EXPERIMENTAL APPROACH

The effects of tramadol and its metabolite mono-O-demethyl-tramadol (M1) on compound action potentials (CAPs) were examined by applying the air-gap method to frog sciatic nerves, and the results were compared with those of other local anaesthetics, lidocaine and ropivacaine.

KEY RESULTS

Tramadol reduced the peak amplitude of the CAP in a dose-dependent manner (IC50=2.3 mM). On the other hand, M1 (1-2 mM), which exhibits a higher affinity for mu-opioid receptors than tramadol, did not affect CAPs. These effects of tramadol were resistant to the non-selective opioid receptor antagonist naloxone and the mu-opioid receptor agonist, DAMGO, did not affect CAPs. This tramadol action was not affected by a combination of the noradrenaline uptake inhibitor, desipramine, and the 5-hydroxytryptamine uptake inhibitor, fluoxetine. Lidocaine and ropivacaine also concentration-dependently reduced CAP peak amplitudes with IC50 values of 0.74 and 0.34 mM, respectively.

CONCLUSIONS AND IMPLICATIONS

These results indicate that tramadol reduces the peak amplitude of CAP in peripheral nerve fibres with a potency which is less than those of lidocaine and ropivacaine, whereas M1 has much less effect on CAPs. This action of tramadol was not produced by activation of mu-opioid receptors nor by inhibition of noradrenaline and 5-hydroxytryptamine uptake. It is suggested that the methyl group present in tramadol but not in M1 may play an important role in producing nerve conduction block.

Evaluating dressing materials for the prevention of shear force in the treatment of pressure ulcers

OBJECTIVE

Shear force is believed to affect pressure ulceration. Therefore, dressing materials that reduce shear force may prevent ulceration and facilitate healing.

METHOD

We measured the following three properties: the coefficient of friction between the outer layer of the dressings and the patient's clothes; the degree of adhesiveness between the inner layer of the dressing and the patient's skin; the transmissibility of shear force of the dressing.

RESULTS

The coefficients of static friction were 1.01 for hydropolymer, 0.72 for hydrofoam and 0.48 for hydrocolloid. Adhesiveness was tested by rolling different sized ball bearings down a slope and over the adhesive lining under both wet and dry conditions. Under dry conditions, the heaviest ball bearing that stopped rolling for five seconds was 111.9g for both hydrofoam and hydrocolloid. Under wet condition, it was 11.9g for hydrofoam and under 1g for hydrocolloid. Tests showed the very low transmissibility (I N buffer) of shear force for hydrofoam, with significant differences between the dressings. Clinical observation has identified good results for hydrofoam when used under highly exuding conditions and for hydrocolloid when used with relatively slight or decreased exudate.

CONCLUSION

Existing dressing materials are being developed and evaluated for wound healing. However, if innovations in the raw materials from which dressings are manufactured could lead to a reduction in shear force and the prevention of pressure ulcers, then dressing materials could be discussed from a viewpoint that is quite different from wound healing.

Sprouting from arteriovenous shunt vessels with increased blood flow

The purpose of this study was to evaluate the effect of increased blood flow on angiogenesis at the large vessels. The arteriovenous (AV) shunt was made on the thigh of male Wistar rats (n = 27) to increase blood flow, wrapped with artificial skin dermis, which consisted of a silicon outer layer, and isolated from surrounding tissues. Blood flow increased from 2.40 +/- 0.77 to 35.8 +/- 8.7 ml min(-1) (14.9 times), and the shear stress index (relative value of shear stress) increased from 10.7 +/- 3.6 to 73.4 +/- 18.1 (6.85 times) 60 min after the shunt formation. Newly formed vessels were observed around the AV shunt loop. Scanning electron micrographs at the AV shunt vessel lumen showed modified endothelial cells at day 7 and a remarkable number of pores at day 14. The volume of newly formed vessels was increased 12 times from day 5 to day 14. The mechanical factor of shear stress was considered the major stimulator of angiogenesis. This is the first report of electron-microscopic observation of sprouts from a large vessel lumen. The new AV shunt model is useful for basic research on angiogenesis at the large vessels in vivo and, furthermore, could generate vascularised tissues with various cultured cells.

Benefits of surgical reconstruction in pressure ulcers with a non-advancing edge and scar formation

OBJECTIVE

To highlight the difficulty in treating pressure ulcers associated with scar formation and the benefits of surgical treatment in these cases by presenting a series of clinical cases.

METHOD

Nine sacral ulcers surrounded by significant scar formation and 14 sacral ulcers without significant scars were treated using the same conservative management protocol. Healing status was quantitatively estimated using an assessment tool called DESIGN, which classifies pressure ulcer severity and allows healing to be monitored; a decreasing score indicates progressive improvement.

RESULTS

Ulcers with scar formation showed little response to the treatment, while those without remarkable scars exhibited a significant decrease of the DESIGN scores. Surgical reconstruction was conducted in five ulcers surrounded by scar formation, and all showed complete healing within extremely short periods.

CONCLUSION

Conservative treatment of pressure ulcers with a non-advancing edge surrounded by scar formation presents considerable difficulties. Surgical reconstruction offers many benefits for non-healing ulcers.

The positive experience of using a growth-factor product on deep wounds with exposed bone

Trafermin, a form of basic fibroblast growth factor, has been used in Japan since 2001. This study investigates whether it can facilitate closure in wounds with deep soft-tissue defects and exposed bone, where surgical closure is not possible.

Functional reorganization of the spinal pain pathways in developmental and pathological conditions

Following inflammation, a subpopulation of Abeta afferents that terminates preferentially in deeper laminae have been shown to extend their axons to the superficial dorsal horn, particularly substantia gelatinosa (SG). Similarly, SG neurons in immature spinal cord receive mainly Abeta afferent inputs. To clarify whether the reorganized sensory pathway in the inflamed rats has a functional similarity with that in the developmental state, we compared synaptic inputs from primary afferents using in vitro and in vivo patch-damp recordings from SG neurons. SG neurons in the mature state had monosynaptic inputs from Adelta and C afferents, while only a few neurons received inputs from Abeta afferents. Following inflammation, the Abeta afferents extended their axons to SG and established functional monosynaptic transmission. Meanwhile, SG neurons in the immature state received preferentially Abeta as well as Adelta afferent inputs, and the majority of Abeta afferent inputs were monosynaptic. These observations support the idea that the sprouting of the large afferent fibres observed in inflamed rats is, at least in part, a regeneration process. However, the process, maybe distinct at some point from the process during development, therefore, produces pathological pain. Though the idea that the regeneration mimics the developmental process has been widely accepted, other possibilities cannot be excluded.

Analysis of receptive fields revealed by in vivo patch-clamp recordings from dorsal horn neurons and in situ intracellular recordings from dorsal root ganglion neurons

It has been thought that spinal dorsal horn neurons receive convergent inputs from not only somatosensory but also visceral pathways. For instance, the referred pain is presumed to be due to the convergence of sensory inputs from cardiac and shoulder receptive fields. However, precise investigation has not been made from dorsal horn neurons yet, because of difficulty in studying the pathways from those regions by means of conventional electrophysiology. The purpose of this study is to clarify the convergent inputs to single dorsal horn neurons from wide receptive fields using an in vivo patch-clamp recording technique from the superficial spinal dorsal horn and an intracellular recording from dorsal root ganglion neurons that keep physiological connections with the peripheral sites. Identified dorsal root ganglion neurons received an input from a quite small area, about 1 x 1 mm in width of the skin. In contrast, substantia gelatinosa neurons in the spinal cord received inputs from an unexpectedly wide area of the skin. Previous extracellular recordings have, however, revealed that substantia gelatinosa neurons have small receptive field. This discrepancy is probably due mainly to an availability of the in vivo patch-clamp method to analyze sub-threshold synaptic responses. In contrast, the extracellular recording technique allows us to analyze predominantly the firing frequency of neurons. Thus, the in vivo patch-clamp recordings from dorsal horn neurons and the intracellular recordings from DRG neurons will be useful for well understanding the sensory processing in the spinal cord.

Depletion of substance P from rat primary sensory neurons by ATP, an implication of P2X receptor-mediated release of substance P

Effects of ATP on substance P immunoreactivity were examined in cultured dorsal root ganglion neurons. We found that treatment of dorsal root ganglion neurons with ATP significantly depleted substance P immunoreactivity on the neurites and somata of the neurons. The effects of ATP were significantly inhibited by the purinergic P2 receptor antagonists suramin (30 microM) and pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (10 microM). We also showed that ATP-induced depletion of substance P immunoreactivity from dorsal root ganglion neurons depended on the entry of Ca(2+). In a spinal cord slice preparation, we also found the internalization of neurokinin-1/substance P receptors in many dorsal horn neurons following the application of ATP or alpha,beta-methylene-ATP. Together these results indicate that activation of P2X receptors may result in release of substance P from primary afferent neurons.

Clinical use of amrinone (a selective phosphodiesterase III inhibitor) in reconstructive surgery

Amrinone is a selective phosphodiesterase III inhibitor that increases cyclic adenosine monophosphate by preventing its breakdown. It is effective in the treatment of congestive heart failure because of its ability to increase myocardial contractility and vascular smooth muscle relaxation. This study was designed to clarify the potential efficacy of amrinone in plastic surgery by clinically assessing its ability to enhance flap blood flow after reconstructive surgery and relieve intraoperative vasospasm. Its effects were compared with those of prostaglandin E1 and lidocaine, which are widely approved agents for improving the hemodynamics of flaps. In the first clinical study, the effects on flap blood flow after flap transfers were investigated. Twenty-six patients underwent reconstructive surgery with vascularized free or pedicled flaps. Blood flow was measured before and 60 minutes after intravenous infusion of lactated Ringer solution (control), amrinone (10 microg/kg/min), or prostaglandin E1 (10 ng/kg/min) using a laser Doppler flowmeter. In the second study, the effects on relief of vasospasm during operation were evaluated. The blood flow of 28 island flaps was measured by laser Doppler flowmetry immediately after flap elevation and 10 minutes after topical application of saline (control), amrinone (5 mg/ml), or lidocaine (10%) to the pedicle in an attempt to resolve the vasospasm. In both clinical studies, the effects of amrinone were statistically no less than those of prostaglandin E1 and lidocaine. The results show that amrinone positively influences the microcirculatory blood flow of transferred flaps and relieves intraoperative vasospasm in clinical cases. The present study suggests that amrinone could be useful for postoperative and intraoperative care in reconstructive surgery.

Mandibular reconstruction using microvascular free flaps: a statistical analysis of 178 cases

For this article, 178 consecutive cases of mandibular reconstruction using microvascular free flaps and performed from 1979 to 1997 were studied. The purpose of this report is to compare flap success rates, complications, and aesthetic and functional results. The ages of the 131 men and 47 women ranged from 13 to 85 years, with an average of 55 years. Donor sites included the rib (11 cases), radius (one case), ilium (36 cases), scapula (51 cases), fibula (34 cases), and soft-tissue flaps with implant (45 cases). Complications included total flap necrosis, partial flap necrosis, major fistula formation, and minor fistula formation. The rate of total flap necrosis involving the ilium and fibula was significantly higher than that of all other materials combined (p < 0.05). The overall rate of implant plate removal, which resulted from the exposure or fracture of the plate, was 35.6 percent (16 of 45 cases). Each mandibular defect was classified by the extent of the bony defect and by the extent of the soft-tissue defect. The extent of the mandibular bony defect was classified according to the HCL method of Jewer et al. The extent of the soft-tissue defect was classified into four groups: none, skin, mucosal, and through-and-through. According to these classifications, functional and aesthetic assessments of deglutition and contour were performed on 115 subjects, and speech was evaluated in 110. To evaluate the postoperative results, points were assigned to each assessment of deglutition, speech, and mandibular contour. Statistical analysis between pairs of bone-defect groups revealed that there was no significant difference in each category. Regarding deglutition, statistical analysis between pairs of soft-tissue-defect groups revealed there were significant differences (p < 0.05) between the none and the mucosal groups and also between the none and the through-and-through groups. Regarding speech, there was a significant difference (p < 0.05) between the none and the through-and-through groups. Regarding contour, there were significant differences (p < 0.01) between the none and the through-and-through groups and between the mucosal and the through-and-through groups. The points given for each function, depending on the reconstruction material, revealed that there was no significant difference between pairs of material groups. From this prospective study, the authors have developed an algorithm for oromandibular reconstruction. When the bony defect is lateral, the ilium, fibula, or scapula should be chosen as the donor site, depending on the extent of the soft-tissue defect. When the bony defect is anterior, the fibula is always the best choice. When the soft-tissue defect is extensive or through-and-through with an anterior bony defect, the fibula should be used with other soft-tissue flaps.

ATP P2X receptor-mediated enhancement of glutamate release and evoked EPSCs in dorsal horn neurons of the rat spinal cord

Presynaptic ATP P2X receptors have been proposed to play a role in modulating glutamate release from the first sensory synapse in the spinal cord. Using spinal cord slice preparations and patch-clamp recordings from dorsal horn neurons in lamina V of the rat spinal cord, we showed that the activation of P2X receptors by alpha,beta-methylene-ATP (alphabetam-ATP) resulted in a large increase in the frequency of spontaneous EPSCs (sEPSCs) and miniature EPSCs (mEPSCs). The increases in mEPSC frequency by alphabetam-ATP were not blocked by the Ca(2+) channel blocker, 30 microm La(3+), but were abolished in a bath solution when Ca(2+) was omitted. The increases in mEPSC frequency by alphabetam-ATP were blocked completely by the P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) at 10 microm. Furthermore, the EPSCs evoked by dorsal root stimulation were potentiated by alphabetam-ATP as well as by the ecto-ATPase inhibitor ARL67156 and were depressed in the presence of P2 receptor antagonists PPADS (10 microm) and suramin (5 microm). The effects of these compounds on the evoked EPSCs were associated with the changes in glutamate release probability of primary afferent central terminals. Our results indicate that alphabetam-ATP-sensitive P2X receptors play a significant role in modulating excitatory sensory synaptic transmission in the spinal cord, and the potential role of endogenous ATP is suggested.