Corneal dermoid in a dwarf rabbit (Oryctolagus cuniculi)

Histology after superficial keratectomy verified our diagnosis of corneal dermoid in a dwarf rabbit (Oryctolagus cuniculi). To our knowledge, this lesion has not been reported previously to occur in dwarf rabbits. Ocular dermoids should be considered as a differential diagnosis for corneal abnormalities in the rabbit.

Cloning and targeted disruption of two polygalacturonase genes in Penicillium olsonii

The filamentous fungus Penicillium olsonii secretes several polygalacturonases (PGs) with molecular masses of about 47 kDa. These enzymes consist of several basic and acidic isoforms, with dominant activities at pI 4.5 and pI 7.9. Two polygalacturonase genes, pg1 and pg2, have been cloned. The corresponding enzymes, PG1 and PG2, consist of 370 and 380 amino acids, respectively, and show significant similarities to endo-polygalacturonases from other filamentous fungi. Targeted disruption of pg1 resulted in the elimination of all basic PG isoforms. In contrast, disruption of pg2 reduced, but did not eliminate the acidic PG activities. The PGs of P. olsonii must therefore be encoded by a gene family of at least three genes. Induction studies with various carbon sources revealed that the acidic and basic isoforms are differentially regulated. Pectin is the best inducer of the acidic PG isoforms. The basic isoforms, however, are best induced by monosaccharides like glucose, alpha-L-rhamnose and alpha-L-arabinose.

Microphysical particle parameters from extinction and backscatter lidar data by inversion with regularization: experiment

We present effective radius, volume, surface-area, and number concentrations as well as mean complex refractive index of tropospheric particle size distributions based on lidar measurements at six wavelengths. The parameters are derived by means of an inversion algorithm that has been specifically designed for the inversion of available optical data sets. The data were taken on 20 June and on 20 July 1997 during the Aerosol Characterization Experiment ACE 2 (North Atlantic/Portugal) and on 9 August 1998 during the Lindenberg Aerosol Characterization Experiment LACE 98 (Lindenberg/Germany). Measurements on 20 June 1997 were taken in a clean-marine boundary layer, and a large value of 0.64 microm for the effective radius, a low value of 1.45 for the real part, and a negligible imaginary part of the complex refractive index were found. The single-scatter albedo was 0.98 at 532 nm. It was derived from the particle parameters with Mie-scattering calculations. In contrast, the particles were less than 0.2 microm in effective radius in a continental-polluted aerosol layer on 20 July 1997. The real part of the complex refractive index was approximately 1.6; the imaginary part showed values near 0.03i. The single-scatter albedo was 0.84. On 9 August 1998 an elevated particle layer located from 3000 to 6000 m was observed, which had originated from an area of biomass burning in northwestern Canada. Here the effective radius was approximately 0.24 mum, the real part of the complex refractive index was above 1.6, the imaginary part was approximately 0.04i, and the single-scatter albedo was 0.81. Excellent agreement has been found with results based on sunphotometer and in situ measurements that were performed during the field campaigns.

Canine neosporosis: clinical and pathological findings and first isolation of Neospora caninum in Germany

Neosporosis was diagnosed in an 11-week-old puppy of the breed Kleiner Münsterländer with progressive hindlimb paresis. Pathohistological and immunohistological examinations revealed a disseminated infection with Neospora caninum. Parasitic stages were demonstrated in the brain, spinal cord, retina, muscles, thymus, heart, liver, kidney, stomach, adrenal gland, and skin. Immunohistochemistry investigations were carried out using polyclonal rabbit antisera developed against N. caninum tachyzoites and the recombinant bradyzoite-specific antigen BAG-5 of Toxoplasma gondii, which is known to cross-react with N. caninum bradyzoites. BAG-5 antibodies recognized tissue cysts within the CNS and some protozoan stages that were not surrounded by a visible cyst wall. All parasite clusters in the retina and some in muscle tissue stained positively with the BAG-5 antiserum. N. caninum was isolated in cell culture and mice inoculated with brain and spinal cord of the puppy. The new isolate is the first reported in Germany and is designated NC-GER1.

Information theoretical performance measure for associative memories and its application to neural networks

We present a general performance measure (information loss) for associative memories based on information theoretical concepts. This performance measure can be estimated, provided that mean values of observables have been determined for the associative memory. Then the estimation guarantees a minimal association quality. The formalism allows the application of the performance measure to complex systems where the relation between input and output of the associative memory is not explicitly known. Here we apply our formalism to the Hopfield model and estimate the storage capacity alpha(c) from the numerically determined information loss. In contrast to other numerical methods the whole overlap distribution is taken into account. Our numerical value alpha(c)=0.1379(4) for the storage capacity in the Hopfield model is below numerical values obtained previously. This indicates that the consideration of small remnant overlaps lowers the storage capacity of the Hopfield model.

Century-scale shifts in early holocene atmospheric CO2 concentration

The inverse relation between atmospheric carbon dioxide concentration and stomatal frequency in tree leaves provides an accurate method for detecting and quantifying century-scale carbon dioxide fluctuations. Stomatal frequency signatures of fossil birch leaves reflect an abrupt carbon dioxide increase at the beginning of the Holocene. A succeeding carbon dioxide decline matches the Preboreal Oscillation, a 150-year cooling pulse that occurred about 300 years after the onset of the Holocene. In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.

Regulation of nitric oxide-responsive recombinant soluble guanylyl cyclase by calcium

Calcium (Ca2+) and cyclic GMP (cGMP) subserve antagonistic functions that are reflected in their coordinated reciprocal regulation in physiological systems. However, molecular mechanisms by which Ca2+ regulates cGMP-dependent signaling remain incompletely defined. In this study, the inhibition of recombinant nitric oxide (NO)-stimulated soluble guanylyl cyclase (SGC) by Ca2+ was demonstrated. The alpha- and beta-subunits of recombinant rat SGC were heterologously coexpressed in HEK 293 cells which do not express NO synthase, whose Ca2+-stimulated activity can confound the effects of that cation on SGC. Ca2+ inhibited basal and NO-stimulated SGC in a concentration- and guanine nucleotide-dependent fashion. This cation inhibited SGC in crude cell extracts and immunopurified preparations. Ca2+ lowered both the Vmax and Km of SGC via an uncompetitive mechanism through direct interaction with the enzyme. In intact HEK 293 cells, increases in the intracellular Ca2+ concentration induced by ionomycin, a Ca2+ ionophore, and thapsigargin, which releases intracellular stores of that cation, inhibited NO-stimulated intracellular cGMP accumulation. Similarly, carbachol-induced elevation of the intracellular Ca2+ concentration inhibited NO-stimulated intracellular cGMP accumulation in HEK 293 cells. These data demonstrate that SGC behaves as a sensitive Ca2+ detector that may play a central role in coordinating the reciprocal regulation of Ca2+- and cGMP-dependent signaling mechanisms.

The optimal radiologic method for assessing spinal canal compromise and cord compression in patients with cervical spinal cord injury. Part II: Results of a multicenter study

STUDY DESIGN

A multicenter, retrospective study using computed tomographic and magnetic resonance imaging data to establish quantitative, reliable criteria of canal compromise and cord compression in patients with cervical spinal cord injury.

OBJECTIVES

To develop and validate a radiologic assessment tool of spinal canal compromise and cord compression in cervical spinal cord injury for use in clinical trials.

SUMMARY OF BACKGROUND DATA

There are few quantitative, reliable criteria for radiologic measurement of cervical spinal canal compromise or cord compression after acute spinal cord injury.

METHODS

The study included 71 patients (55 men, 16 women; mean age, 39.7 +/- 18.7 years) with acute cervical spinal cord injury. Causes of spinal cord injury included motor vehicle accidents (n = 36), falls (n = 20), water-related injuries (n = 8), sports (n = 5), assault (n = 1), and farm accidents (n = 1). Canal compromise was measured on computed tomographic scan and T1- and T2-weighted magnetic resonance imaging, and cord compression at the level of maximum injury was measured on T1- and T2-weighted magnetic resonance imaging. All films were assessed by two independent observers.

RESULTS

There was a strong correlation of canal compromise and/or cord compression measurements between axial and midsagittal computed tomography, and between axial and midsagittal T2-weighted magnetic resonance imaging. Spinal canal compromise assessed by computed tomography showed a significant although moderate correlation with spinal cord compression assessed by T1- and T2-weighted magnetic resonance imaging. Virtually all patients with canal compromise of 25% or more on computed tomographic scan had evidence of some degree of cord compression on magnetic resonance imaging, but a large number of patients with less than 25% canal compromise on computed tomographic scan also had evidence on magnetic resonance imaging of cord compression.

CONCLUSIONS

In patients with cervical spinal cord injury, the midsagittal T1- and T2-weighted magnetic resonance imaging provides an objective, quantifiable, and reliable assessment of spinal cord compression that cannot be adequately assessed by computed tomography alone.

Percutaneous dilatational tracheostomy: results and long-term outcome of critically ill patients following cardiac surgery

BACKGROUND

Tracheostomy is widely regarded as the method of choice for long-term airway control in critically ill patients. The advantages of tracheostomy have to be balanced against the surgical risks of conventional surgical tracheostomy. However, the alternative technique of percutaneous dilatational tracheostomy (PDT) has been associated with fewer procedure-related complications.

METHODS

The results of PDT following cardiac surgery were investigated in a prospective study (1/1995-9/1997). The procedure of Ciaglia (1985), a modified Seldinger technique, was performed under endoscopic guidance in 88 patients, 30 women and 58 men, with a mean age of 56.6+/-14.5 years.

RESULTS

PDT was successfully performed in all cases after a mean of 14.6+/-9.0 days of translaryngeal intubation. No serious procedural complications occurred; a minor hemorrhage occurred in 12 patients and a cuff defect in 2 patients. 49 patients (55.7%) were weaned from mechanical ventilation, and 45 patients (51.1%) were decannulated after a mean tracheostomy duration of 18.9+/-27.2 days. 38 patients died of their underlying disease while still being mechanically ventilated. A total of 20 postprocedural complications were observed in 15 patients: stomal infection (7), minor hemorrhage (4), tracheal stenosis (3), tube displacement (2), delayed wound healing (2), soft-tissue hemorrhage (1), and organ hemorrhage (1). During long-term follow-up a good functional and cosmetic result could be documented in the majority of 35 patients.

CONCLUSIONS

PDT can be performed safely in patients following cardiac surgery as a bedside technique with a low incidence of procedural and postprocedural complications and an acceptable functional and cosmetic long-term outcome. Further studies are needed to define the optimal timing of PDT after translaryngeal intubation.

Prevention of initial perfusion failure during xenogeneic ex vivo liver perfusion by selectin inhibition

BACKGROUND

Endothelial cell activation triggered by xenoreactive antibodies and complement products is the main feature of discordant xenograft rejection. The contribution of early cell-mediated mechanisms to this rejection process is poorly understood, and the function of adhesion molecules in xenogeneic cell interactions in vivo is unclear. The aim of the study was to investigate the role of selectins in mediating cell-dependent initial perfusion failure and functional restrictions in xenoperfused guinea pig (GP) livers.

METHODS

Isolated GP livers were hemoperfused in a flow-constant, recirculating perfusion system via the portal vein. Microhemodynamic parameters such as sinusoidal perfusion rate and leukocyte flux were analyzed using intravital fluorescence microscopy. Hepatic oxygen consumption and bile production, as well as liver enzymes, potassium level, and numbers of white blood cells and platelets in the perfusate, were determined. The GP livers were perfused either with GP blood (control perfusion), with unmodified rat blood (xenoperfusion), or with rat blood treated with the selectin-blocking polysaccharide Fucoidin.

RESULTS

A significant sinusoidal perfusion failure was observed in the xenoperfusion group, which was accompanied by distinct signs of a functional restriction-like reduced oxygen consumption, bile production, and increased perfusion pressure. However, there were significantly fewer impairments in the Fucoidin group. Furthermore, fewer platelets were trapped and a smaller number of stagnant leukocytes were observed in this group.

CONCLUSION

Fucoidin did not suppress complement activation during xenoperfusion. Considering that Fucoidin inhibits the selectin-dependent interactions among white blood cells, platelets, and sulfate-containing proteoglycans on the surface of vascular endothelium, these findings suggest an important role for early cellular interactions in the development of organ failure during xenogeneic rejection.

Methylprednisolone or tirilazad mesylate administration after acute spinal cord injury: 1-year follow up. Results of the third National Acute Spinal Cord Injury randomized controlled trial

OBJECT

A randomized double-blind clinical trial was conducted to compare neurological and functional recovery and morbidity and mortality rates 1 year after acute spinal cord injury in patients who had received a standard 24-hour methylprednisolone regimen (24MP) with those in whom an identical MP regimen had been delivered for 48 hours (48MP) or those who had received a 48-hour tirilazad mesylate (48TM) regimen.

METHODS

Patients for whom treatment was initiated within 3 hours of injury showed equal neurological and functional recovery in all three treatment groups. Patients for whom treatment was delayed more than 3 hours experienced diminished motor function recovery in the 24MP group, but those in the 48MP group showed greater 1-year motor recovery (recovery scores of 13.7 and 19, respectively, p=0.053). A greater percentage of patients improving three or more neurological grades was also observed in the 48MP group (p=0.073). In general, patients treated with 48TM recovered equally when compared with those who received 24MP treatments. A corresponding recovery in self care and sphincter control was seen but was not statistically significant. Mortality and morbidity rates at 1 year were similar in all groups.

CONCLUSIONS

For patients in whom MP therapy is initiated within 3 hours of injury, 24-hour maintenance is appropriate. Patients starting therapy 3 to 8 hours after injury should be maintained on the regimen for 48 hours unless there are complicating medical factors.

Methylprednisolone or tirilazad mesylate administration after acute spinal cord injury: 1-year follow up

Object

A randomized double-blind clinical trial was conducted to compare neurological and functional recovery and morbidity and mortality rates 1 year after acute spinal cord injury in patients who had received a standard 24-hour methylprednisolone regimen (24MP) with those in whom an identical MP regimen had been delivered for 48 hours (48MP) or those who had received a 48-hour tirilazad mesylate (48TM) regimen.

Methods

Patients for whom treatment was initiated within 3 hours of injury showed equal neurological and functional recovery in all three treatment groups. Patients for whom treatment was delayed more than 3 hours experienced diminished motor function recovery in the 24MP group, but those in the 48MP group showed greater 1-year motor recovery (recovery scores of 13.7 and 19, respectively, p = 0.053).A greater percentage of patients improving three or more neurological grades was also observed in the 48MP group (p = 0.073). In general, patients treated with 48TM recovered equally when compared with those who received 24MP treatments. A corresponding recovery in self care and sphincter control was seen but was not statistically significant. Mortality and morbidity rates at 1 year were similar in all groups.

Conclusions

For patients in whom MP therapy is initiated within 3 hours of injury, 24-hour maintenance is appropriate. Patients starting therapy 3 to 8 hours after injury should be maintained on the regimen for 48 hours unless there are complicating medical factors.

[Eye diseases in dwarf rabbits. 2. Diseases of the cornea, intraocular and retrobulbar disorders, and neoplasms]

In the second part of this review article the diseases affecting the cornea, intraocular and retrobulbar disorders, and eye-neoplasia of dwarf rabbits are described. These are illustrated by means of selected photographs.

Analysis of the microcirculation during xenogeneic liver perfusion in the guinea pig--rat model. The contribution of leukocytes to the rejection process

Since the main feature of hyperacute rejection is a disturbance of the xenograft's microcirculation, we analyzed microhemodynamic parameters during xenogeneic hemoperfusion of the guinea pig (GP) liver and investigated the contribution of leukocytes to the rejection process using intravital fluorescence microscopy. Isolated GP livers were hemoperfused via the portal vein in a recirculating system with a constant flow of 1 ml/min per g liver. In contrast to isogeneic perfusion with heparinized GP blood, a disturbance in the microcirculation was observed during xenogeneic perfusion using heparinized rat blood, with significantly higher values of perfusion pressure, reduced sinusoidal perfusion rates, and a larger number of stagnant leukocytes. A complete breakdown of the microcirculation, with the highest values of perfusion pressure and the smallest perfusion index, was associated with 100% accumulated leukocytes when rat blood was anticoagulated with sodium citrate. Almost isogeneic perfusion values were obtained when fucoidin, which inhibits L-selectin-dependent cell interaction, was added to heparinized rat blood. These data indicate that leukocyte-endothelial cell interaction contributes to xenogeneic rejection.

[Eye diseases in dwarf rabbits. 1. Anatomy, investigation procedures, diseases of the eyelid, the conjunctiva and the nasolacrimal duct]

The clinical ophthalmology of dwarf rabbits is reviewed in this continuing article. The first part contains the ophthalmological examination scheme and anatomical features of the rabbit's eye. Furthermore diseases of the eyelids, conjunctiva and of the nasolacrimal duct are described. These are illustrated by means of selected photographs.

Organs from animals for man

In the following review some of the problems of xenotransplantation shall be discussed, based on the few experimental data available so far and on reports in the literature describing investigations which may be of importance for xenotransplantation. The impact of gravity on the upright posture of man versus almost all other mammals, the dysfunction between enzymes and hormones in different species and the lack of interactions between interleukins, cytokines and vasoactive substances will be taken into consideration. The question must be asked whether different levels of carrier molecules or serum proteins play a role in the physiological network. Even though the development of transgenic animals or other imaginative manipulations may lead to the acceptance of any type of xenografted organ, it has to be established for how long the products of the xenografts are able to act in the multifactorial orchestra. We are far from understanding xenogeneic molecular mechanisms involved in toxicity, necrosis and apoptosis or even reperfusion injury and ischemia in addition to the immediate mechanisms of the hyperacute xenogeneic rejection. Here, cell adhesion, blood clotting and vasomotion collide and bring micro- and macrocirculation to a standstill. All types of xenogeneic immunological mechanisms studied so far were found to have a more serious impact than those seen in allogeneic transplantation. In addition we are now only beginning to understand that so-called immunological parameters in allogeneic mechanisms act also in a true physiological manner in the xenogeneic situation. These molecular mechanisms occur behind the curtain of hyperacute, accelerated, acute or chronic xenograft rejection of which only some folds have been lifted to allow glimpses of part of the total scene. Other obstacles are likely to arise when long-term survival is achieved. These obstacles include retroviral infections, transfer of prions and severe side effects of the massive immunosuppression which will be needed. Moral, ethical and religious concerns are under debate and the species-specific production of proteins of the foreign donor species developed for clinical use suddenly appears to be a greater problem than anticipated.

Microhemodynamics and leukocyte sequestration after pulmonary ischemia and reperfusion in rabbits

OBJECTIVE

Investigation of leukocyte sequestration in alveolar capillaries and of microhemodynamic changes after pulmonary ischemia/reperfusion injury.

METHODS

The kinetics of leukocyte passage and the hemodynamics in pulmonary microcirculation were investigated in 16 rabbits by intravital microscopy. Mean red blood cell velocity and the number of sticking leukocytes were measured in pulmonary arterioles, venules, and capillaries after 1 hour of tourniquet ischemia and 10 minutes and 1 hour after reperfusion.

RESULTS

The decrease of red blood cell velocity after reperfusion was associated with a largely increased heterogeneity of blood flow. Immediately after the onset of blood flow, sequestered leukocytes were found in all microvascular segments. An increased number of leukocytes was present in arterioles, venules, and alveolar capillaries 10 minutes and 1 hour after reperfusion. Concomitantly, width of alveolar septa was increased while arterial oxygen tension was reduced, indicating the development of interstitial pulmonary edema.

CONCLUSION

Leukocytes are sequestered after pulmonary ischemia and reperfusion not only in alveolar capillaries but also in arterioles and venules, and they may contribute to the development of reperfusion edema.

[Application of indirect immunofluorescence in blood group serology]

Indirect fluorescence flow cytometry allows the quantification of erythrocytes with aberrant phenotype and the quantification of antigen density. These tasks may be performed using commercial blood group antisera. With adequate standardization, a variation coefficient < 5% for antigen density is achievable. Analysis of chimerism is of special interest after bone marrow transplantation.