Subsea permafrost organic carbon stocks are large and of dominantly low reactivity

Subsea permafrost carbon pools below the Arctic shelf seas are a major unknown in the global carbon cycle. We combine a numerical model of sedimentation and permafrost evolution with simplified carbon turnover to estimate accumulation and microbial decomposition of organic matter on the pan-Arctic shelf over the past four glacial cycles. We find that Arctic shelf permafrost is a globally important long-term carbon sink storing 2822 (1518-4982) Pg OC, double the amount stored in lowland permafrost. Although currently thawing, prior microbial decomposition and organic matter aging limit decomposition rates to less than 48 Tg OC/yr (25-85) constraining emissions due to thaw and suggesting that the large permafrost shelf carbon pool is largely insensitive to thaw. We identify an urgent need to reduce uncertainty in rates of microbial decomposition of organic matter in cold and saline subaquatic environments. Large emissions of methane more likely derive from older and deeper sources than from organic matter in thawing permafrost.

The Clinical Outcome of Early Periprosthetic Joint Infections Caused by Staphylococcus epidermidis and Managed by Surgical Debridement in an Era of Increasing Resistance

INTRODUCTION

A risk factor for the failure of surgical debridement in patients with early periprosthetic joint infections (PJI) is the presence of multidrug-resistant microorganisms. Staphylococcus epidermidis is one of the most isolated microorganisms in PJI and is associated with emerging resistance patterns. We aimed to assess the antibiotic resistance patterns of S. epidermidis in early PJIs treated with surgical debridement and correlate them to clinical outcomes.

MATERIAL AND METHODS

A retrospective multicentre observational study was conducted to evaluate patients with an early PJI (within 3 months after the index arthroplasty) by S. epidermidis with at least two positive intraoperative cultures. Clinical failure was defined as the need for additional surgical intervention or antibiotic suppressive therapy to control the infection.

RESULTS

A total of 157 patients were included. The highest rate of resistance was observed for methicillin in 82% and ciprofloxacin in 65% of the cases. Both were associated with a higher rate of clinical failure (41.2% vs. 12.5% (p 0.048) and 47.3% vs. 14.3% (p 0.015)), respectively. Furthermore, 70% of the cases had reduced susceptibility to vancomycin (MIC ≥ 2), which showed a trend towards a higher failure rate (39.6% vs. 19.0%, NS). Only 7% of the cases were rifampin-resistant. Only the resistance to fluoroquinolones was an independent risk factor for clinical failure in the multivariate analysis (OR 5.45, 95% CI 1.67-17.83).

CONCLUSION

S. epidermidis PJIs show a high rate of resistance. Resistance to fluoroquinolones is associated with clinical failure. Alternative prophylactic antibiotic regimens and optimising treatment strategies are needed to improve clinical outcomes.

[Early recognition of cancerous lesions in the mouth and oropharynx: Automated evaluation of hyperspectral image stacks]

BACKGROUND

Early detection of cancerous lesions is still crucial for a patient's prognosis. Although diagnostic access to the oral cavity and oropharynx is comparably easy, the incidence of resulting disease remains high. This is due to the fact that in many cases, malignity is recognized too late on a purely visual basis. Previously, we discussed the application of hyperspectral imaging for early detection of precancerous and cancerous lesions of the larynx. This time, we evaluate the method in the oral cavity and oropharynx.

MATERIALS AND METHODS

In 85 patients scheduled for endoscopy, hyperspectral imaging was performed. We used a rigid 0-degree endoscope, a light-adjustable monochromator, and a hyperspectral camera. For evaluation of the method, 3 patients were chosen exemplarily. Training sites from physiological and cancerous tissues were marked. Hyperspectral data from 1 patient were used to train a classifier, which was then used for automatic detection of precancerous and cancerous lesions in another 2 patients.

RESULTS

Intraoperative hyperspectral imaging was performed without any problems. Classification showed sensitivities of 61 and 43%, and a specificity of 100%.

CONCLUSION

This proof-of-concept study underscores the high potential of hyperspectral imaging for early recognition of cancer in the mouth and oropharynx. Besides a better prognosis for cancer patients, this approach could lead to higher cost efficiency in the health system.

[Hyperspectral imaging in head & neck oncology]

Hyperspectral Imaging has long been established in other scientific disciplines than medicine (e. g. earth science) as a means for objective classification of image data information. Some 10 years ago it was first introduced into medicine. Due to its immanent advantages - non-destructive specimen, compatibility with established optical tools (microscope, endoscope), objectivity, and user-independence - several attempts have been made in order to use its potential for the treatment of cancer patients. This publication reviews which methods have been developed for analogue issues in disciplines other than medicine, how these can be transferred into medicine, and what the perspectives are for the traditional innovative field of head-and-neck-oncology.

Direct observation of nonaffine tube deformation in strained polymer networks

We present a one-to-one comparison of polymer segmental fluctuations as measured by small angle neutron scattering in a network under deformation with those obtained by neutron spin echo spectroscopy. This allows an independent proof of the strain dependence of the chain entanglement length. The experimentally observed nonaffine square-root dependence of the tube channel on strain is in excellent agreement with theoretical predictions and permits us to exclude an often invoked nondeformed as well as affinely deformed tube.

Hepatocellular Injury of Nonischemic Liver Tissue after Selective Clamping in Rats – Protective Action by Pharmacological Pretreatment with Lipoic Acid

BACKGROUND/AIM

The aim of the study was to characterize the hepatic injury (HI) of the nonischemic liver lobe after selective portal triad clamping and investigate the influence of pharmacological pretreatment with alpha-lipoic acid (LA).

METHODS

Brown-Norway rats received 500 micromol LA injected via the inferior vena cava 15 min prior to the induction of 90 min of selective ischemia. Another group of rats received vehicle prior to ischemia. Both groups were compared with sham-operated animals.

RESULTS

Lipid peroxidation (LPO) was increased in the ischemic as well as in the nonischemic liver tissue (NIL) in the untreated group. Levels of adenosine triphosphate and reduced glutathione content of the nonischemic liver lobe were decreased in the untreated group 1 h after reperfusion. Activity of caspases 3 and 8 was not detectable, whereas expression of the Bax protein was demonstrated in the NIL. We observed areas of necrotic hepatocytes and large gaps of sinusoids in the NIL of the untreated rats. LA attenuated LPO as well as Bax expression in the NIL. Moreover adenosine triphosphate and glutathione content of the NIL was increased 1 h after reperfusion by LA. LA pretreatment reduced release of alpha-glutathione-s-transferase in plasma. Histology of the nonischemic liver lobe did not markedly differ from sham-operated animals after LA pretreatment.

CONCLUSION

HI of the NIL seems to be mediated by LPO and proapoptotic proteins such as Bax. Besides its described potential to reduce ischemia/reperfusion injury of the ischemic lobe, LA attenuates HI of the nonischemic tissue after selective portal triad clamping.

Mechanical effect of van der waals interactions observed in real time in an ultracold Rydberg gas

We present time-resolved spectroscopic measurements of Rydberg-Rydberg interactions between two Rydberg atoms in an ultracold gas, revealing the pair dynamics induced by long-range van der Waals interactions between the atoms. By detuning the excitation laser, a specific pair distribution is prepared. Penning ionization on a microsecond time scale serves as a probe for the pair dynamics under the influence of the attractive long-range forces. Comparison with a Monte Carlo model not only explains all spectroscopic features but also gives quantitative information about the interaction potentials. The results imply that the interaction-induced ionization rate can be influenced by the excitation laser. Surprisingly, interaction-induced ionization is also observed for Rydberg states with purely repulsive interactions.

Biliodigestive anastomosis after intraoperative irradiation in swine

A large animal model was established to investigate the feasibility and suitable dosage of intraoperative radiation therapy (IORT) to the hepatic hilum before biliary-enteric anastomosis is performed. Twenty-two Pietrain Hampshire pigs underwent gallbladder and proximal bile duct resection followed by IORT using 20-40 Gy and performing biliary-enteric anastomosis. In the follow-up period of 56 days, pigs developed dose-dependent complications like stenosis of the biliary-enteric anastomosis. Results demonstrate that IORT of the liver hilum up to 20 Gy is safe with acceptable early complications in the presented animal model. The porcine biliary-enteric anastomosis can tolerate intraoperative irradiation up to a dosage of 40 Gy without disruption.

ICRA noises: artificial noise signals with speech-like spectral and temporal properties for hearing instrument assessment. International Collegium for Rehabilitative Audiology

Current standards involving technical specification of hearing aids provide limited possibilities for assessing the influence of the spectral and temporal characteristics of the input signal, and these characteristics have a significant effect on the output signal of many recent types of hearing aids. This is particularly true of digital hearing instruments, which typically include non-linear amplification in multiple channels. Furthermore, these instruments often incorporate additional non-linear functions such as "noise reduction" and "feedback cancellation". The output signal produced by a non-linear hearing instrument relates to the characteristics of the input signal in a complex manner. Therefore, the choice of input signal significantly influences the outcome of any acoustic or psychophysical assessment of a non-linear hearing instrument. For this reason, the International Collegium for Rehabilitative Audiology (ICRA) has introduced a collection of noise signals that can be used for hearing aid testing (including real-ear measurements) and psychophysical evaluation. This paper describes the design criteria, the realisation process, and the final selection of nine test signals on a CD. Also, the spectral and temporal characteristics of these signals are documented. The ICRA noises provide a well-specified set of speech-like noises with spectra shaped according to gender and vocal effort, and with different amounts of speech modulation simulating one or more speakers. These noises can be applied as well-specified background noise in psychophysical experiments. They can also serve as test signals for the evaluation of digital hearing aids with noise reduction. It is demonstrated that the ICRA noises show the effectiveness of the noise reduction schemes. Based on these initial measurements, some initial steps are proposed to develop a standard method of technical specification of noise reduction based on the modulation characteristics. For this purpose, the sensitivity of different noise reduction schemes is compared by measurements with ICRA noises with a varying ratio between unmodulated and modulated test signals: a modulated-unmodulated ratio. It can be anticipated that this information is important to understand the differences between the different implementations of noise reduction schemes in different hearing aid models and makes.

Temporary pancreatic duct occlusion by ethibloc: cause of microcirculatory shutdown, acute inflammation, and pancreas necrosis

Temporary obliteration of the pancreatic duct has been suggested to be beneficial in chronic pancreatitis, segmental pancreatic transplantation, and following Roux-Y pancreaticojejunostomy. Little is known, however, as to whether obliteration of the duct alters exocrine pancreatic physiology. Therefore we studied in male inbred Lewis rats the immediate effects of Ethibloc-induced duct obliteration (Ethibloc: Ethicon, Norderstedt, Germany) on pancreatic microcirculation, inflammation, and tissue injury (n = 8), and compared these effects with those caused by experimental pancreatitis (4% sodium taurocholate; n = 8). Animals receiving an intraductal infusion of saline served as controls (n = 8). Duct occlusion with Ethibloc resulted in a marked decrease (p < 0.05) in capillary red blood cell (RBC) velocity and functional capillary density (FCD) to 88 +/- 39 microm/s (baseline 716 +/- 40 microm/s) and 72 +/- 33 cm(-1) (baseline 493 +/- 21 cm(-1)), respectively, which was even more pronounced when compared with that observed in experimental pancreatitis (333 +/- 62 microm/s and 195 +/- 44 cm(-1), respectively). In parallel, the manifestation of tissue damage was found to be more severe after Ethibloc; and chloracetate esterase staining showed a larger number of infiltrating leukocytes [555 +/- 86/high power field (HPF) versus pancreatitis: 160 +/- 12/HPF; p < 0.05). We conclude that intraductal application of Ethibloc induces significant microcirculatory failure and a marked inflammatory response, which are even more pronounced when compared with the changes observed with experimental pancreatitis. Based on these results and the fact that there is no direct proof for a benefit of temporary duct occlusion by Ethibloc, it is proposed that the procedure be reevaluated for its use in pancreatic surgery.

Cloning and recombinant expression of the La RNA-binding protein from Trypanosoma brucei

We report the isolation, cloning and recombinant expression of a Trypanosoma brucei homolog of the La RNA-binding protein. Based on peptide sequence information we have isolated a cDNA clone which encodes a protein of 335 amino acids with a predicted molecular weight of 37.7 kDa. The amino acid sequence fits the domain structure of known La proteins and contains a putative ATP-binding site located in the COOH-terminal domain. The cDNA was expressed as a glutathione S-transferase fusion protein in Escherichia coli, and the recombinant protein displayed RNA-binding activity in an electrophoretic mobility shift assay.

Surface cooling inhibits tumor necrosis factor-alpha-induced microvascular perfusion failure, leukocyte adhesion, and apoptosis in the striated muscle

BACKGROUND

Surface cooling is frequently used in a number of conditions, especially traumatic, ischemic, burn, and neurologic injury to reduce the tissue damage. However, the protective mechanisms of cold therapy on traumatized tissues remain unclear. Tumor necrosis factor-alpha (TNF-alpha) is a fundamental mediator in inflammatory reactions and trauma-induced tissue injury. In the present study, we examined the microvascular response to TNF-alpha challenge and the effects of local cooling on the TNF-alpha-induced changes in the striated muscle of hamsters.

METHODS

By the use of the dorsal skinfold chamber preparation and in vivo fluorescence microscopy in combination with computer-based image analysis, we determined TNF-alpha-induced leukocyte rolling and adhesion to microvascular endothelium, capillary perfusion, venular leakage, and cellular apoptosis with and without surface cooling.

RESULTS

We found that topical administration of 2000 units TNF-alpha caused a progressive impairment of microvascular perfusion and increased leukocyte recruitment and vascular macromolecular leakage. Local cooling to 10 degrees C for 60 minutes markedly (P < .05) inhibited the TNF-alpha-induced capillary perfusion failure and leukocyte response and slightly attenuated the increase of microvascular permeability after 180 minutes of stimulation. Furthermore, it was observed that 24 hours of TNF-alpha stimulation increased the number of apoptotic cells (i.e., nuclear condensation and fragmentation) by 10-fold. This TNF-alpha-mediated effect was almost abolished by treatment with local hypothermia.

CONCLUSION

These data suggest that the protective effect of surface cooling of traumatized tissue is due to its attenuation of the microvascular inflammatory response associated with the inhibition of the process of apoptosis.

Synthetic peptides identify the minimal substrate requirements of tubulin polyglutamylase in side chain elongation

The minimal sequence requirement of Crithidia tubulin polyglutamylase is already fulfilled by tubulin-related peptides carrying a free alpha-carboxylate on a glutamic acid residue. Since the product of each glutamylation step fulfills the substrate requirements necessary for the next cycle, very long side chains are generated with brain tubulin as a substrate. Up to 70 mol of glutamic acid was incorporated per alphabeta-heterodimer. We speculate that the strict choice of a particular glutamate residue for the formation of the isopeptide bond initiating a novel side chain is made by a tubulin monoglutamylase which requires the entire tubulin as substrate.

ET-1 induces pancreatitis-like microvascular deterioration and acinar cell injury

Using in vivo microscopy red blood cell (RBC) velocities, functional capillary density (FCD) and capillary diameters were estimated after inducing acute pancreatitis by intraductal infusion of sodium taurocholate (0.8 ml; 4%) or after topical superfusion of the pancreas with ET-1 (100 pmol). Sodium taurocholate mediated a significant decrease in RBC velocities between 50 and 70%, transient decrease in capillary diameters by 10%, and a sustained decrease in FCD between 60 and 70% paralleled by a dramatic heterogeneity in blood flow. Topical superfusion of the exteriorized pancreas with ET-1 caused a significant decrease in RBC velocities between 65 and 75%, a sustained decrease in capillary diameters by 10%, and a decrease in FCD by 45% accompanied by an increase in flow heterogeneity. Following sodium taurocholate infusion pancreas histology revealed a severe edema and sublobular acinar cell necrosis, while topical ET-1 application displayed a severe edema of the pancreas with focal acinar cell necrosis. Thus, ET-1 mediated a deterioration of the pancreatic microcirculation, which is similar to the microcirculatory failure found in sodium taurocholate-induced experimental pancreatitis and was associated with focal acinar cell necrosis. We are thus inclined to hypothesize that endothelin released by injured endothelial cells during acute biliary pancreatitis promotes microcirculatory failure and ischemia in acute pancreatitis, eventually leading to acinar cell necrosis.

Isolation of tubulin polyglutamylase from Crithidia; binding to microtubules and tubulin, and glutamylation of mammalian brain alpha- and beta-tubulins

Trypanosomatids have a striking cage-like arrangement of submembraneous microtubules. We previously showed that alpha- and beta- tubulins of these stable microtubules are extensively modified by polyglutamylation. Cytoskeletal microtubular preparations obtained by Triton extraction of Leishmania tarentolae and Crithidia fasciculata retain an enzymatic activity that incorporates radioactive glutamic acid in a Mg2+-ATP-dependent manner into alpha- and beta-tubulins. The tubulin polyglutamylase is extracted by 0.25 M salt. The Crithidia enzyme can be purified by ATP-affinity chromatography, glycerol-gradient centrifugation and ion-exchange chromatography. After extraction from the microtubular cytoskeleton the glutamylase forms a complex with alphabeta tubulin, but behaves after removal of tubulin as a globular protein with a molecular mass of 38x10(3). In highly enriched fractions a corresponding band is the major polypeptide visible in SDS-PAGE. The enzyme from Crithidia recognises mammalian brain tubulin, where it incorporates glutamic acid preferentially into the more acidic variants of both alpha- and beta-tubulins. Synthetic peptides with an oligoglutamyl side chain, corresponding to the carboxy-terminal end of brain alpha- and beta-tubulins, are accepted by the enzyme, albeit at low efficiency. The polyglutamylase elongates the side chain by up to 3 and 5 residues, respectively. Other properties of the tubulin polyglutamylase are also discussed.

Microvascular response to compartment syndrome-like external pressure elevation: an in vivo fluorescence microscopic study in the hamster striated muscle

OBJECTIVE

To quantitatively assess the nature and the magnitude of the microvascular response of striated muscle tissue upon elevation of external pressure, as in compartment syndrome.

METHODS

Using the skinfold chamber model in Syrian golden hamsters and intravital fluorescence microscopy, we studied the individual response of the different segments of the microcirculation, i.e., the arterioles, capillaries, and postcapillary venules, in terms of vasomotor control (change of vessel diameter) and cessation of blood flow upon defined changes in external tissue pressure.

RESULTS

The unique findings of our study are that (1) arteriolar flow ceased at mean external pressures of 25.6+/-2.4, 28.3+/-2.8, 34.5+/-4.6, and 44.4+/-6.8 mm Hg in vessels with diameters of less than 20, 20 to 40, 40 to 60, and greater than 60 microm, respectively, without signs of spasm or collapse even at a pressure maximum of 70 mm Hg, whereas (2) in venules the increase of external pressure was associated with a diameter reduction ranging from 5 to 25% with cessation of blood flow at mean external pressures between 27 and 33 mm Hg. Blood flow ceased in 50% of the muscle capillaries already at an external pressure of 12 mm Hg. Thus, at distinct external pressure levels venous and capillary blood flow ceased, but arterioles were still capable of carrying flow, which was directed along arteriolo-arteriolar "thoroughfare" channels. To restart blood flow, external pressure had to be decreased by 9, 11, 15, and 17 mm Hg in arterioles with diameters of less than 20, 20 to 40, 40 to 60, and greater than 60 microm, and by approximately 9 mm Hg in venules regardless of vessel diameter. Capillary blood flow was found to be restored at a mean reduction of external tissue pressure of approximately 4 mm Hg.

CONCLUSION

Our study disproves the critical closing theory but complies-in particular because of the supposed constriction-induced increase of venular resistance-with the hypothesis of reduced arteriovenous pressure gradients as the cause of flow cessation in compartment syndrome. The necessity of a substantially increased perfusion pressure gradient to restart blood flow in arterioles, capillaries, and venules confirms the existence of yield stress in these microvessels. The high susceptibility of capillaries to elevated external pressure indicates the necessity of early fasciotomy to restore impaired nutritive circulation in cases of compartment syndrome.

Effects of local cooling on microvascular hemodynamics and leukocyte adhesion in the striated muscle of hamsters

OBJECTIVES

Cellular metabolism is dependent on the local temperature in tissues. Induced hypothermia has been shown to be protective in a number of conditions, especially traumatic, ischemic, burn, and neurological injury. However, the protective mechanisms of cold therapy remain controversial and the hemodynamic changes in the microcirculation of striated muscles in response to hypothermia have not been studied in detail previously.

METHODS

In this study, we investigated the microvascular response of local cooling and rewarming in the striated muscle of hamsters by use of the dorsal skinfold preparation and in vivo fluorescence microscopy.

RESULTS

We found that reduction of the surface temperature to 8 degrees C for 30 minutes caused arteriolar vasoconstriction with a decrease in diameters by 43+/-7% while the venular and capillary diameters remained unchanged. The cooling procedure also markedly reduced the functional capillary density and the blood flow velocity and diameters in all vessel types, i.e., arterioles, venules, and capillaries. Moreover, the percentage of capillaries with no flow increased from 0.4+/-0.5% to 44+/-14% after 10 minutes of cold therapy. However, these hemodynamic changes induced by local hypothermia were completely reversed to the precooling values after termination of cooling and 30 min of rewarming. Strikingly, we found no increase in the number of adherent leukocytes and vascular permeability after the cooling and rewarming period, while, in contrast, additional experiments with warm ischemia (30 minutes) and reperfusion (30 minutes), i.e., reduced microvascular perfusion and reperfusion at normothermia, caused a sustained decrease in local perfusion and a nine-fold increase in venular leukocyte adhesion.

CONCLUSIONS

Taken together, our functional data demonstrate that hypothermia markedly reduces microvascular perfusion, which is completely restored upon rewarming. The reduced microvascular perfusion during hypothermia did not provoke an inflammatory response, whereas leukocyte recruitment was prominent after reduced perfusion at normothermia, indicating that transient hypothermia has no adverse effects on microvascular parameters in the striated muscle in vivo.

Somatostatin attenuates microcirculatory impairment in acute sodium taurocholate-induced pancreatitis

Using in vivo microscopy, red blood cell (RBC) velocities, functional capillary density (FCD), and overall changes in capillary blood flow (PI) were estimated following intraductal infusion of sodium taurocholate (0.8 ml; 4%) alone or in combination with systemic administration of somstostatin (single bolus SMS 100 microg/100 g body wt). Sodium taurocholate mediated a significant transient decrease in RBC velocities and a sustained decrease in FCD, which were paralleled by dramatic flow heterogeneity. Therefore, a significant reduction in overall capillary blood flow was calculated. Additional SMS treatment reduced microcirculatory impairment as expressed by reduction of blood flow heterogeneity, a less rarified functional capillary density, and a recovery of RBC velocities and acinar capillary overall perfusion to control values. As a result of this microcirculatory improvement, pancreas histology revealed slightly less severe tissue damage compared to the non-SMS-treated pancreatitis group. These findings demonstrate that exogenous SMS infusion can improve microcirculatory failure in acute biliary pancreatitis, which should have a beneficial effect on the course of the disease.

Posttranslational modifications of alpha- and beta-tubulin in Giardia lamblia, an ancient eukaryote

Tubulin of Giardia lamblia, a representative of the oldest eukaryotes, was screened for posttranslational modifications. Mass spectrometry of the carboxy-terminal peptides documents a large number of variants. Both alpha- and beta-tubulin show polyglycylation with up to 20 and 15 extra glycyl residues respectively. Minor variants show a low level of glutamylation without or with glycylation. The glutamylation-specific antibody GT335 detects alpha- and beta-tubulin in immunoblots. The terminal tyrosine is fully retained in alpha-tubulin, which is completely acetylated at Lys-40. Thus except for the detyrosination/tyrosination cycle all posttranslational modifications known for higher eukaryotes are already present in Giardia.

Effects of somatostatin (SMS) on pancreatic microcirculation

The effect of bolus infusion of increasing somatostatin (SMS) concentrations (1, 10, 100, 200 micrograms/100 g body wt) on pancreatic microcirculation and pancreatic tissue PO2 were investigated by using in vivo epifluorescence microscopy and a polarographic PO2 measurement technique. Additionally, the microperfusion of the pancreas, liver, spleen, stomach, and duodenum was measured by a laser Doppler device. Bolus infusion of SMS caused a significant, transient, and dose-dependent decrease in pancreatic capillary RBC velocities (to 50% of baseline) and acinar capillary overall perfusion (to 20% of baseline), which was not caused by a macrocirculatory depression. This pronounced decrease in microperfusion was not paralleled by a decline in tissue PO2. Laser Doppler measurements revealed that pancreatic and gastric microperfusion were reduced only at maximal SMS concentrations, considering that microperfusion of the liver, spleen, and duodenum was not altered. Therefore, we found further evidence that circulatory adjustment might occur during SMS inhibited secretory activity of the exocrine pancreas.

Acute pancreatitis in rats: effects of sodium taurocholate, CCK-8, and Sec on pancreatic microcirculation

With use of in vivo microscopy, pancreatic duct permeability, red blood cell (RBC) velocities, functional capillary density (FCD), and overall changes in capillary blood flow (perfusion index) were estimated after intraductal infusion of sodium taurocholate (0.8 ml, 4%) alone or in combination with systemic administration of cholecystokinin (CCK, 0.3 microg/100 g body wt) or secretin (Sec, 10 microg/100 g body wt). Sodium taurocholate mediated a significant increase in pancreatic duct and capillary permeability within 105 +/- 26 s followed by a transient decrease in RBC velocities and a sustained decrease in FCD, which were paralleled by dramatic flow heterogeneity. Therefore, a significant reduction in overall capillary blood flow was calculated. CCK stimulation aggravated the microcirculatory failure due to a decrease in RBC velocities, which was accompanied by an increase in acinar cellular necrosis. Sec stimulation attenuated microcirculatory failure due to a more moderate reduction of FCD. The enhanced pancreatic duct and capillary permeability, which enables free diffusion of pancreatic digestive enzymes into the parenchyma, is the initiating event in acute biliary pancreatitis, causing microcirculatory failure and tissue damage. The microcirculatory changes are secondary and a propagating factor for the development of acini necrosis. Stimulation with CCK worsened the course of acute biliary pancreatitis.

A frequent polymorphism of the gene mutated in ataxia telangiectasia

The gene mutated in ataxia telangiectasia (AT), the ATM gene, has recently been cloned and shown to encode a multi-domain protein with homology to cell-cycle regulators. We report here an intragenic restriction fragment length polymorphism of the ATM gene that is common in the German population with allele frequencies of 0.56 and 0.44, respectively. Observed heterozygosity approximated 50% in healthy individuals as well as in 152 randomly selected breast cancer patients. We present a simple and rapid polymerase chain reaction (PCR)-based assay for this dimorphism that should be useful to trace the inheritance of ATM alleles in ataxia telangiectasia and breast cancer families and to study loss of heterozygosity in primary tumours.

The importance of functional magnetic resonance imaging (MRI) in the planning of stabilizing operations on the cervical spine in rheumatoid patients

Chronic inflammatory diseases, such as chronic polyarthritis or spondylarthritis ankylopoietica, can occasionally lead to vertebral instabilities of the occipitoatlantal or atlantoaxial level, requiring some form of stabilizing operation. By means of functional magnetic resonance imaging, i.e., with the cervical spine at its maximal range of flexion and extension, performed on 11 patients suffering from an instability at the above level, it was possible to demonstrate not only the extent of synovial tissue, but also how this sometimes excessive soft-tissue growth hinders an adequate reduction of the subluxated vertebrae. The importance of this investigation lies in the fact that the necessary operation can be planned appropriately. As such, three patients required a decompressing operation entailing resection of the posterior arch of the atlas, widening of the foremen magnum, or both.