[Arthrocentesis in rheumatology practice]

This study of Norwegian rheumatologists' use of intraarticular steroid injections is based on a survey among members of the Norwegian Society for Rheumatology. 79% of the members responded, i.e. 108 rheumatologists. 69 reported having used intraarticular steroid injections in any joint during the last week, a total of 637 times. There have been no previous studies on this subject in Norway. The results show that Norwegian rheumatologists consider intraarticular steroid injections a very effective treatment. Only 9% reported that they had seen side effects over the last 12 months (a total of 51 side effects), of which post-injection pain and subcutaneous atrophy were the most common. There were no reports of septic arthritis. Almost all side effects were considered not serious.

Liver infiltrating T lymphocytes express interferon gamma and inducible nitric oxide synthase in chronic hepatitis C virus infection

BACKGROUND

Pathogenesis of hepatitis C virus (HCV) associated liver injury is thought to be due to the host antiviral immune response. Using a quantitative, competitive RT-PCR technique, we recently showed that expression of interferon gamma (IFN-gamma) and IFN-gamma inducible type of nitric oxide synthase (iNOS) is increased in homogenised liver tissue of patients with chronic HCV infection.

AIMS

To determine the cellular origin of IFN-gamma and iNOS expression and to examine the hypothesis that T cell derived IFN-gamma secretion induces iNOS in hepatocytes in chronic HCV infection.

METHODS

By applying a non-radioactive in situ hybridisation method combined with indirect immunofluorescence, 33 liver biopsy specimens from patients with chronic HCV infection were studied for cellular expression of IFN-gamma and iNOS mRNA.

RESULTS

In chronic HCV infection, both IFN-gamma and iNOS gene expression were significantly increased. IFN-gamma and iNOS mRNA were observed in CD3+ lymphocytes infiltrating portal tracts and hepatic lobules, but not in hepatocytes.

CONCLUSIONS

Results are consistent with previous reports that IFN-gamma and iNOS transcripts are elevated in chronic HCV infection. In contrast to the hypothesis, IFN-gamma expressing T cells do not induce iNOS in hepatocytes, but probably in T cells. T lymphocytes expressing IFN-gamma and/or iNOS have the potential to participate in autocrine and paracrine pathways that may contribute to the pathobiology of chronic hepatitis C.

Systemic and splanchnic endothelin-1 plasma levels in liver cirrhosis before and after transjugular intrahepatic portosystemic shunt (TIPS)

AIMS/BACKGROUND

Endothelin-1 (ET-1) may be a mediator for portal hypertension in liver cirrhosis. The aim of the present study was to determine the concentrations of ET-1 in the systemic and splanchnic circulation before and after reduction of portal hypertension by transjugular intrahepatic portosystemic shunt implantation (TIPS).

METHODS

Plasma concentrations of immunoreactive ET-1 were measured in peripheral venous blood samples from 25 patients with liver cirrhosis before and at 1, 3, 9 and 15 months after TIPS. Furthermore, acute effects of TIPS on ET-1 were studied in plasma samples from the hepatic vein, the portal vein 30 minutes before and after TIPS and in the femoral artery (only after TIPS) in a subgroup of 15 patients. In addition, the portocaval pressure gradient was determined before and after TIPS.

RESULTS

Before TIPS peripheral venous plasma ET-1 concentrations (n=25; median 4.2 pg/ml; range 1.9-14.7) were significantly increased in patients with refractory ascites (n=7; median 7.8, range 3.5 14.7) compared to patients with repetitive bleeding (n=18; median 3.4; range 1.9-7.1) (p=0.003). Furthermore, peripheral ET-1 concentrations correlated with the degree of liver dysfunction according to the Child-Pugh classification (Spearman's r=0.46; p=0.02). Following TIPS, peripheral ET-1 concentrations remained unchanged during a follow-up of 15 months. Before TIPS, a positive gradient of ET-1 concentrations from portalvenous to hepatovenous and peripheral venous levels was found (p<0.03). Immediately after TIPS, arterial ET-1 concentrations reached markedly increased levels in individual patients (88, 92 and 103 pg/ml). Severe systemic reactions to these high levels were not observed. Peripheral venous, hepatovenous and portalvenous ET-1 concentrations did not correlate with portocaval pressure gradients.

CONCLUSION

Cirrhotic patients demonstrated unchanged peripheral venous ET-1 concentrations up to 15 months after TIPS. Portal congestion was associated with increased ET-1 levels in the prehepatic splanchnic area. The effect of portal decompression on splanchnic and systemic ET-1 levels deserves further investigation.

Normal proteolytic processing of the presenilins

The majority of familial Alzheimer's disease (AD) cases are linked to mutations of the presenilin 1 and 2 (PS1, PS2) genes on chromosomes 14 and 1, respectively (1-3). PS1 and PS2 are about 67% identical in amino acid sequence. Based on hydrophobicity analysis, the presenilins are predicted to have multiple transmembrane domains. Structural analysis (see Chapter 19 }) suggest that presenilins are 6-8 transmembrane proteins which are located in the endoplasmic reticulum (ER) and Golgi. The N- and C-termini and the large hydrophilic loop region are oriented to the cytoplasm (4,5). More than 40 AD-causing mutations have been identified in PS1, whereas only two mutations have been identified in PS2. The disease-causing mutations span most domains of the protein, with clusters of mutations in the second transmembrane domain and the large hydrophilic loop region Fig. 1).

[Significance of respiratory compensation in acidosis in calves]

The respiratory component PvCO2 of acid-base-status was observed in n = 36 calves (age: x +/- s = 8.7 +/- 5.0 d) with neonatal diarrhea and an acidosis (venous blood-pH: < 7.30; x +/- s = 7.08 +/- 0.15). In n = 10 (28%) calves with a severe metabolic acidosis (pH: x +/- s = 7.03 +/- 0.12; BE: x +/- s = -22.1 +/- 5.3 mmol/l) the PvCO2 was decreased < 5.3 kPa (x +/- s = 4.5 +/- 0.5 kPa) and showed a distinct respiratory compensation. A PvCO2 between 5.3-6.7 kPa (x +/- s = 6.0 +/- 0.4 kPa) was observed in n = 16 (44%) acidotic calves (pH: x +/- s = 7.11 +/- 0.13; BE: x +/- s = -15.2 +/- 7.4 mmol/l). These n = 26 (72%) calves showed a simple metabolic acidosis which is well known for calves with neonatal diarrhea. The remaining n = 10 (28%) calves showed an increase of the PvCO2 > 6.7 kPa (x +/- s = 8.0 +/- 1.5 kPa). These animals had a mixed respiratory-metabolic acidosis (pH: x +/- s = 7.08 +/- 0.20; BE: x +/- s = -13.9 +/- 10.3 mmol/l), as the decrease of the pH could not be determined by the decreased metabolic component HCO3- of acid-base-status alone. Calves which died during hospitalization and calves with a PvCO2 > 6.7 kPa tended to be younger and showed partially significant lower values for the parameters of oxygen-supply PvO2 and SvO2. Lactate was significantly higher in dying calves but not in calves with a mixed acidosis which on the other hand were more dehydrated. The functional capacity of respiratory compensation of acidotic disorders in the calves studied promised to be almost the same as in dog and man. One reason for the failure of respiratory compensation in some calves could be a more severe hypovolemia. With the use of "venous hypoxemia" (decrease PvO2 and decrease SvO2) the detection of tissue hypoxia was easier than with lactate concentration.

Increase of anaerobic degradation of particulate organic matter in full-scale biogas plants by mechanical maceration

Different concepts of implementation of mechanical pretreatment for enhancing the biogas potential from fibers in manure feedstock were evaluated by sampling before and after macerators at different biogas plants and from a fiber separation unit. An increase of the biogas potential of up to 25% by pretreatment of the whole feed in the macerator before the reactor was observed. Implementation concepts with a treatment of the fibers alone after separation from the manure showed to be not efficient due to a low recovery of organic matter in the fibers by the separation unit. The low operational costs of a macerator make it attractive to use this pretreatment method for a more complete degradation of particulate organic matter. Investigation of the size distribution of the fibers showed that a change in biogas potential was not correlated to a smaller size of the fibers. Results from the macerators indicate that the biodegradability of the fibers is rather enhanced by shearing which is not necessarily reflected by a change in fiber size.

Elevated serum levels of astroglial S100beta in patients with liver cirrhosis indicate early and subclinical portal-systemic encephalopathy

Portal-systemic encephalopathy is the prototype among the neuropsychiatric disorders that fall under the term Hepatic Encephalopathies. Ammonia toxicity is central to the pathophysiology of Portal-systemic encephalopathy, and neuronal ammonia toxicity is modulated by activated astrocytes. The calcium-binding astroglial key protein S100beta is released in response to glial activation, and its measurement in serum only recently became possible. Serum S100beta was determined by an ultrasensitive ELISA in patients (n=36) with liver cirrhosis and transjugular intrahepatic portosystemic stent-shunt. Subclinical portal-systemic encephalopathy and overt portal-systemic encephalopathy were determined by age-adjusted psychometric tests and clinical staging, respectively. Serum S100beta, was specifically elevated in the presence of subclinical or early portal-systemic encephalopathy, but not arterial ammonia. S100 levels elevated above a reference value (S100beta < or = 110pg/ml) or the cut off value determined in our group of patients (112pg/ml) predicted subclinical portal-systemic encephalopathy with a specificity and sensitivity of 100 and 56.5%, respectively. Serum S100beta was significantly dependent on liver dysfunction (Child-Pugh score), but was more closely related to cognitive impairments than the score. Serum S100beta seems to be a promising biochemical surrogate marker for mild cognitive impairments due to portal-systemic encephalopathy.

The experiences and views of parents who care for ventilator-dependent children

Discussion in this paper is drawn from the literature examining the management of children with long-term assisted ventilation, and a study of parents' experiences and views of caring for their ventilator-dependent child at home. Difficulties in undertaking research into this group of children are highlighted. Recommendations are proposed regarding future multidisciplinary, multiagency service development in order to meet the needs of ventilator-dependent children and their families.

Different gene expression of MDM2, GAGE-1, -2 and FHIT in hepatocellular carcinoma and focal nodular hyperplasia

Overexpression and/or mutations of oncogenes, tumour suppressor genes and tumour rejection genes have been observed in several human malignancies. Their analyses might be of diagnostic importance. Therefore, malignant hepatocytes derived from hepatocellular carcinoma (HCC) tissue as well as non-malignant hepatocytes derived from focal nodular hyperplasia (FNH) were studied. Samples containing normal human hepatocytes (HC) served as controls. Cellular material was obtained by fine-needle aspiration biopsy guided by ultrasound. Cells were analysed for expression and mutation of the oncogene MDM2, the genes GAGE-1, -2 coding for tumour-associated antigens and the candidate tumour suppressor gene FHIT. Different patterns of non-mutant FHIT transcripts including precise deletion of exons were found in 7/10 HCC, 2/10 FNH and 2/10 HC. However, expression of non-mutant GAGE-1, -2 RNA was demonstrated exclusively in 6/10 HCC samples. Further genetic features specific of HCC were point mutations in a zinc-finger motif of MDM2 (3/10 HCC samples). Neither GAGE-1, -2 expression nor MDM2 mutations were observed in the FNH samples, or in normal hepatocytes. Our findings suggest that occurrence of variable FHIT transcripts is not restricted to hepatic malignant tumours. In contrast, MDM2 mutations and GAGE-1, -2 expression were associated with HCC specimens. Therefore, the RT-PCR assays for GAGE-1, -2 and MDM2 might be useful adjuncts in cytodiagnosis of liver neoplasms.

Characterization of the insulin-like growth factor axis in a human hepatoma cell line (PLC)

The insulin-like growth factors (IGF-I and -II) are structurally related peptides participating in the regulation of metabolism, growth and cellular differentiation. In the present study, the human hepatoma cell line PLC was studied for the expression of individual components of the IGF axis. Northern blot analysis using IGF-I and -II coding cDNAs failed to detect IGF-I- or -II-specific transcripts in total RNA from PLC cells. Biosynthesis of type I and II IGF receptors was demonstrated by northern blotting and binding studies as well as cross-linking of the respective radiolabeled ligand. Both IGF-I and -II stimulated [3H]-thymidine incorporation dose-dependently. The mitogenic activity of exogenously added IGFs was reduced by the presence of IGF-binding proteins of 24, 30, 34, 41 and 45 kDa in supernatants of PLC cells identified as IGFBP-4, -1, -2 and -3, respectively, by [125I]IGF-I ligand-, immuno- and northern blotting. Biosynthesis of IGFBP-3 was stimulated dose-dependently by IGF-I and -II, while IGFBP-1, -2 and -4 were not affected. The increase of IGFBP-3 in response to IGF-I and -II was due to a stimulation of IGFBP-3 specific mRNA as well as to an inhibition of IGFBP-3 endocytosis. Proteolytic activity for rhIGFBP-3 was detected in media from PLC cells at acidic pH that was inhibited by the aspartyl protease inhibitor pepstatin A as well as after immunodepletion of cathepsin D from media of PLC cells. Thus, a role of cathepsin D for the regulation of IGFBP-3 bioavailability via endocytosis in acidic prelysosomal compartments was suggested. The susceptibility of PLC for IGF-I and -II was restricted by their ability to increase the abundance of inhibitory IGFBPs and to decrease the level of IGF-I receptor expression. The present data point to the IGF axis as a complex regulatory system that self limits the mitogenic activity of exogenous IGFs.

Portosystemic hepatic encephalopathy after transjugular intrahepatic portosystemic shunt in patients with cirrhosis: clinical, laboratory, psychometric, and electroencephalographic investigations

A prospective study of hepatic encephalopathy (HE) including neuropsychiatric and psychometric evaluation, electroencephalography, and determination of arterial ammonia levels was performed in 55 cirrhotic patients treated consecutively by transjugular intrahepatic portosystemic shunt (TIPS). The cumulative HE rate increased from 23.6% within the 3-month interval before TIPS to 50. 9% within the first 3-month interval post-TIPS (P = .003). Significant and independent predictors of HE post-TIPS were the presence of HE pre-TIPS and reduced liver function. The cumulative HE rate declined in the second 3-month interval post-TIPS and reached the pre-TIPS level. Chronic forms of HE exceeding grade I were not observed. In a subgroup of 22 nonencephalopathic TIPS patients, the prevalence of subclinical HE did not change after TIPS. Among individual psychometric tests, the block design test gave the highest proportion of pathological results (about 50%), whereas selective reminding gave the lowest (10%-25%). Electroencephalography (EEG) showed a temporary increase of pathological results at 1 month after TIPS, when patients with overt HE (grade I) were included (proportion of 21.1% before vs. 57.1%, P = .005). Arterial ammonia concentration increased from a mean of 94 +/- 26 microgram/dL to 140 +/- 28 microgram/dL at 3 months after TIPS (P < .001). Elevated ammonia levels persisted. TIPS led to a temporary increase of HE incidence within 3 months. The decline of the HE rate beyond 3 months despite a sustained increase of arterial ammonia levels could not entirely be explained by reduction of shunt flow, nor by alteration of liver function. Instead, cerebral adaptation to gut-derived neurotoxins might be anticipated.

Destabilization of beta-catenin by mutations in presenilin-1 potentiates neuronal apoptosis

Mutations of the presenilin-1 gene are a major cause of familial early-onset Alzheimer's disease. Presenilin-1 can associate with members of the catenin family of signalling proteins, but the significance of this association is unknown. Here we show that presenilin-1 forms a complex with beta-catenin in vivo that increases beta-catenin stability. Pathogenic mutations in the presenilin-1 gene reduce the ability of presenilin-1 to stabilize beta-catenin, and lead to increased degradation of beta-catenin in the brains of transgenic mice. Moreover, beta-catenin levels are markedly reduced in the brains of Alzheimer's disease patients with presenilin-1 mutations. Loss of beta-catenin signalling increases neuronal vulnerability to apoptosis induced by amyloid-beta protein. Thus, mutations in presenilin-1 may increase neuronal apoptosis by altering the stability of beta-catenin, predisposing individuals to early-onset Alzheimer's disease.

Bright basal ganglia in T1-weighted magnetic resonance images are frequent in patients with portal vein thrombosis without liver cirrhosis and not suggestive of hepatic encephalopathy

BACKGROUND/AIMS

Deposition of paramagnetic substances in basal ganglia, resulting in increased signals in T1-weighted magnetic resonance images (bright basal ganglia), is frequently seen in liver cirrhosis. The present study describes the prevalence of bright basal ganglia and its clinical significance in patients with long-standing portal vein thrombosis in the absence of liver cirrhosis.

METHODS

Six patients with angiographically proven complete portal vein thrombosis and cavernomatous transformation without signs of acute or chronic liver disease were studied by magnetic resonance imaging of the brain, neuropsychiatric evaluation, psychometric tests, electroencephalography, and determination of arterial ammonia levels and of serum manganese concentrations from peripheral venous blood.

RESULTS

Five out of six patients demonstrated increased signal intensity in the basal ganglia. Overt portal-systemic encephalopathy was not noted prior to or at the time of evaluation. Normal EEG results were recorded in all patients. Only one of the six patients had pathological results in at least two out of four psychometric tests. This latter patient had had a large right-sided brain infarction. Arterial ammonia concentrations were normal in four of the six patients; one patient with increased ammonia levels had concomitant renal insufficiency with azotemia. The other four patients had no relevant concomitant diseases. Serum manganese levels were non-significantly increased compared with a control group (p=0.06), but they were significantly correlated to basal ganglia signal intensity (R=0.88; p=0.02).

CONCLUSIONS

Our results demonstrate that bright basal ganglia primarily represent shunt-induced alterations. They are not directly associated with disturbed liver function nor with portal-systemic encephalopathy.

Hepatitis C virus infection-associated non-cryoglobulinaemic monoclonal IgMkappa gammopathy responsive to interferon-alpha treatment

BACKGROUND/AIMS

An association of HCV infection with lymphoproliferative disorders, particularly B-cell non-Hodgkin's lymphoma has been described. In the majority of reported patients, mixed cryoglobulinaemia was present as well. Rarely, HCV-associated lymphoproliferative disorders have been observed in the absence of cryoglobulinaemia. In these latter patients, the response to interferon-alpha is largely unknown.

CASE REPORT

We report a case of an asymptomatic 31-year-old male with chronic HCV infection and non-cryoglobulinaemic monoclonal IgMkappa gammopathy responsive to interferon-alpha therapy. Prior to therapy, elevated plasma transaminase activities known for longer than a year, serum anti-HCV antibodies and HCV RNA detected by reverse transcriptase-polymerase chain reaction were present. Serum IgM concentration was markedly elevated, immunofixation demonstrated monoclonal serum IgM, and urine kappa-light chains were detected. Cryoglobulins were undetectable in several consecutive serum samples. Bone marrow aspirate and biopsy specimens were unremarkable. Further evaluation, e.g. by ultrasonography and radiography, did not reveal evidence for lymphoma. Treatment with interferon-alpha2a for 12 months resulted in a long-term sustained response to HCV infection and in a normalisation of serum IgM concentration.

CONCLUSION

Therefore, the corresponding effects of interferon-alpha on HCV infection and on a monoclonal B-cell population observed in the present case might suggest a pathogenetic connection, similarly, to what has been described for HCV and mixed cryoglobulinaemia. The molecular events, however, leading to HCV-induced monoclonal B-cell expansion remain unknown.

Situs inversus of donor or recipient in liver transplantation

Situs inversus is a rare anatomical abnormality that is often associated with multiple, complex malformations. In the past, patients with situs inversus were considered unsuitable candidates for transplantation or organ donation because associated visceral, and especially vascular, anomalies pose special technical difficulties. Recently, several cases of successful liver transplantation in recipients with situs inversus have been published using modified surgical techniques. This report reviews the literature and describes our own experience, including two liver graft recipients with complete and incomplete situs inversus, and one patient who underwent successful transplantation using a liver from a donor with situs inversus.

[Doppler sonographic short- and long-term studies of portal hemodynamics following transjugular intrahepatic portasystemic shunt (TIPSS)]

Shunt insufficiency due to shunt occlusion or stenosis is frequent after TIPS (about 50% after one year). Controversially discussed is whether Doppler sonography is effective in detecting shunt stenosis or whether regular angiographies are required. The experience with a noninvasive method of surveillance primarily based on Doppler sonography is reported here. 58 patients (35 men, 23 women, mean age 55 years, range 33-82 years) were treated by TIPS because of complications of portal hypertension (43 x gastroesophageal bleeding, 14 x refractory ascites, 1 x venoocclusive disease). Liver cirrhosis (alcoholtoxic etiology in 63%) was present in 55 cases, according to Child-Pugh's classification 23 patients = A, 19 patients = B and 13 patients = C. Within a mean observation period of 14 months, Doppler sonography was performed in three months intervals, endoscopy in six months intervals and angiography only when shunt insufficiency was suspected by Doppler sonography and/or because of clinical events, e.g. recurrent bleeding. Immediately after TIPS, maximal flow velocity and flow volume in the portal vein increased by 116% and 115%, respectively. Three months later, a significant increase of portal vein diameter of about 15% was measured. Shunt flow was initially 2.700 ml/min (one week after TIPS) and decreased progressively by about 30% within the first nine months of follow-up. Correspondingly, angiographically proven shunt insufficiency was present in 22 patients (33 episodes). A total of twelve bleeding episodes recurred in seven patients (rebleeding rate of 16% after one year and 19% after two years). In the remaining 15 patients (68%; 21 episodes) shunt insufficiency could be corrected prior to complications because of detection by Doppler sonography (19x) and endoscopy (2x). Therefore, Doppler sonography is an effective diagnostic tool for the detection of shunt insufficiency and should be performed at three months intervals for at least 18 months. In this context it appears allowable to avoid routine angiographies.

Characterization of the IGF axis components in isolated rat hepatic stellate cells

The insulin-like growth factors I and II (IGF-I, -II) are circulating peptides known to participate in the regulation of metabolism, growth, and cellular differentiation. In the present study, "early cultured" (days 2-3 of culture) and "culture-activated" (days 6-7 of culture) rat hepatic stellate cells (HSCs) were analyzed for expression of individual components of the IGF axis. Northern blot analysis of IGF-I messenger RNA (mRNA) revealed transcripts of 7.5, 4, 2, and 1.0 to 1.5 kb in culture-activated HSCs, while early cultured HSCs did not express IGF-I mRNA. In culture-activated HSCs, an IGF-I secretion of 8.3+/-2.5 ng/10(6) cells per 24 hours was determined radioimmunologically. In media from early cultured HSCs, IGF-I was not detectable. The IGF-I receptor (IGF-I-R) mRNA expression was three-fold higher in early cultured HSCs than in culture-activated HSCs. By immunohistochemistry, a decrease of IGF-I-R expression of HSCs in vivo following CCl4-induced liver damage was noted as well. IGF binding proteins (IGFBPs) were detected in conditioned media from HSCs by 125I-IGF-I ligand blotting at apparent molecular masses of 24 and 41 to 45 kd that were immunologically identified as IGFBP-4 and -3, respectively. Synthesis of these IGFBPs increased with time of culture. At neutral pH, no IGFBP proteolysis was observed in conditioned media of early cultured and culture-activated HSCs, whereas at acidic pH, protease activities against IGFBP-3 and -4 were detectable. IGFBP protease activities were completely abolished by inhibitors of aspartyl and cysteine proteases. Addition of 100 nmol/L IGF-I stimulated cell proliferation of early cultured HSCs 5.6+/-1.1- and 4.6+/-0.2-fold as measured by [3H]thymidine and 5-bromo-2'-deoxyuridine incorporation, respectively. In culture-activated HSCs, proliferation was increased 1.2+/-0.1-fold in the presence of 100 nmol/L IGF-I in both proliferation assays. It can be concluded that due to a higher expression of the IGF-I-R and lower levels of IGFBPs, early cultured HSCs are more susceptible to the mitogenic actions of IGFs than the culture-activated HSCs. The present data suggest a role for the IGF axis components in the initiation rather than the perpetuation of HSC proliferation during hepatic fibrogenesis.

Mouse insulin-like growth factor binding protein-6: expression, purification, characterization and histochemical localization

The mitogenic and metabolic activities of insulin-like growth factors (IGF) are modulated by a family of six high affinity IGF binding proteins (IGFBPs). This study describes the expression of the mouse IGFBP-6 which is unique among IGFBPs in its preferential binding of IGF II, in insect cells using the baculovirus system. The purified, O-glycosylated IGFBP-6 was functional as shown by IGF binding and by inhibition of IGF II-stimulated DNA synthesis in human fibroblasts. Specific antibodies generated in chicken against the recombinant IGFBP-6 were used for Western blotting analysis and immunohistochemistry. Strong immunoreactivity was found in ossifying bones of the cranial base, in cell clusters of the pancreas anlage, in the trigeminal ganglion, on myoblasts, on motoneurons of the spinal cord of embryonic mice. In tissues of adult mouse, strong IGFBP-6 immunostaining was present in epidermal and peridermal layers of the skin, in meningeal layers, in long-striated skeletal muscle, and in the Langerhans' islets of the pancreas. No immunopositive staining was observed in lung and liver indicating that sites of synthesis and IGFBP action are different.

Transjugular intrahepatic portosystemic stent-shunt after orthotopic liver transplantation in a patient with early recurrence of portal hypertension of unknown origin

A 65-year-old italian patient developed complicated portal hypertension immediately after orthtopic liver transplantation (OLT) necessitating shunt creation. One to five weeks after OLT, massive ascitic fluid losses of up to 121/day developed. Vascular and major hepatic-parenchymal abnormalities were excluded by duplexsonography, angiography and initial histology, respectively. A peritoneovenous shunt (Denver-shunt) on day 31 after OLT reduced (by about 50%) but did not stop ascitic fluid losses. Furthermore, three variceal bleedings occurred after implantation of the Denver-shunt. Direct portography on day 45 after OLT revealed portal hypertension (pressure gradient of 26 mmHg) requiring the implantation of a transjugular intrahepatic portosystemic stent-shunt (TIPS) leading to a reduction of the pressure gradient to 13 mmHg. Subsequently, ascites resolved within ten days and esophageal varices improved. Liver function parameters normalized inspite of recurrence of HCV infection with detection of HCV RNA in serum already in the fifth week after OLT. During follow-up, histological findings deteriorated from mild changes to extended fibrosis at day 61 after OLT, which might have contributed to the maintenance of portal hypertension. The deterioration of liver histology was accompanied by an improvement/normalization of liver graft function. There was no evidence for additional viral liver infections, e.g. hepatitis B or cytomegalovirus infection. This case illustrates an etiologically unclear syndrome developing directly after OLT and reaffirms the effectiveness of TIPS in the treatment of complicated portal hypertension even after liver transplantation.

Small airway patency in infants with apparent life-threatening events

A reduction in specific airway conductance has been reported in infants with a history of an apparent life-threatening event (ALTE). It is unclear, however, whether this reflects upper or lower airway narrowing. We performed a controlled study to determine small airway patency in infants with ALTE. Lung function tests were performed in 26 infants with a history of ALTE and 27 healthy controls. Partial expiratory flow-volume curves were obtained during quiet sleep using the rapid chest compression technique; thoracic gas volume (TGV) and expiratory airway resistance (RAW) were measured by whole body plethysmography. Compliance of the respiratory system (Crs) was measured using the single breath occlusion technique. The median maximal flow at functional residual capacity (VmaxFRC) was 85 ml/s (range 10-198 ml/s) in patients and 123 (range 47-316 ml/s) in controls (P = 0.003). VmaxFRC corrected for TGV was 0.5 s(-1) (range 0.06-1.3 s[-1]) and 0.9 s(-1) (range 0.4-1.8 s[-1]), respectively (P = 0.001). TGV, RAW and Crs were not significantly different between patients and controls.

CONCLUSION

Reduced small airway patency may play a role in the pathogenesis of ALTE.

In vitro reactivity of cryoglobulin IgM and IgG in hepatitis C virus-associated mixed cryoglobulinemia

BACKGROUND/AIMS

Mixed cryoglobulinemia is frequently associated with chronic hepatitis C virus infection. We aimed to clarify the mechanism, kinetics and participating proteins in cryoprecipitate formation, which are still being debated.

METHODS

Eighteen patients with cryoglobulinemia were studied. Isolated serum cryoprecipitates and purified cryoglobulin IgM and IgG fractions were analyzed in vitro by turbidimetry for temperature-dependent complex formation. Immunoglobulin reactivity, i.e. in cryoprecipitates and in cryoglobulin-free sera, was studied using immunoblot and enzyme immunoassays. HCV RNA was detected by reverse transcriptase/polymerase chain reaction.

RESULTS

By turbidimetry, purified cryo-IgM precipitated (in the absence of HCV RNA) with cryo-IgG as well as with non-cryoglobulin IgG and with IgG Fc or F(ab')2 fragments. In contrast, purified cryo-IgG did not precipitate with non-cryoglobulin IgM. Anti-HCV IgG reactivity was found in cryoglobulin-free sera, in cryoprecipitates and in purified cryoglobulin IgG fractions. The respective titers were similar. Purified cryo-IgM did not react to HCV-encoded proteins. Binding of cryo-IgM to heterologous IgG was inhibited by intact IgG (up to a mean of about 52%) as well as by IgG Fc (33%) and F(ab')2 fragments (17%). Binding of cryo-IgM to IgG was enhanced at low temperature (4 degrees C vs. 37 degrees C), particularly for type III cryoglobulin IgM.

CONCLUSIONS

In hepatitis C virus-associated cryoglobulinemia the in vitro precipitate formation depended on cryo-IgM, while IgG appeared to act as an unspecific antigenic partner. Hepatitis C viral particles were probably not required. Cryo-IgM binding occurred primarily to intact IgG. Anti-HCV reactivity of either cryo-IgM or cryo-IgG was not necessary for precipitate formation. Regarding the pathogenesis, a direct hepatitis C virus protein-dependent stimulation of B-cells producing cryo-IgM seems to be unlikely.

[Pathogenesis and diagnosis of systemic acidosis in animals with conclusions for effective forms of therapy]

Intermediary metabolism produces daily approximately 285 mmol hydrogen ions per kilogramm metabolic body weight (BWkg 0.75). If the lung fails to eliminate the volatile acid H2CO3 sufficiently and/or if the kidneys do not eliminate the also produced nonvolatile acids a retention of acids in the organism results. This way, as well as increased acid production through metabolic processes, leads to a systemic acidosis. Systemic acidosis develops after a primary dysfunction of an organ. If there is only one cause of an acid-base-disturbance, e.g. metabolic acidosis, the organism will respond with compensation by the correspondent organ, e.g. the lung, which reduces the drop in the pH. If metabolic and respiratory acidosis occur simultaneously normal compensation is impaired and the fall in the pH is greater by additive effects. This can lead to a severe, life-threatening decline in the blood-pH (< 7.00). If the pH falls from normal value of 7.40 below 7.20, buffer therapy is necessary. Most alkalinizing agents in veterinary medicine, such as bicarbonate, lactate or acetate are only effective after increased pulmonary elimination of CO2 produced in buffer reactions. These substances are not suitable and are even contraindicated in therapy of primary respiratory or mixed respiratory-metabolic acidosis. New buffer agents, e.g. an equimolar mixture of NaHCO3 and Na2CO3 (= Carbicarb) open new promising possibilities in the treatment of acidotic disorders in animals. However clinical trials to determine the efficacy of Carbicarb in animals are still to be conducted.

[Refractory hydrothorax in primary biliary cirrhosis: successful treatment with transjugular intrahepatic portosystemic stent shunt]

HISTORY AND CLINICAL FINDINGS

A 55-year-old woman with known primary biliary cirrhosis (PBC) was hospitalized because of increasing dyspnoea. A year before she had for the first time experienced a right-sided pleural effusion which had to be drained every 4 weeks. Physical examination revealed dullness on percussion and greatly decreased breath sounds on auscultation over the entire right thorax. In addition there were signs of moderate ascites and leg oedema.

INVESTIGATIONS

Chest radiograph showed a homogeneous shadowing of the right thorax without mediastinal shift. Diagnostic thoracocentesis produced a serous effusion, a transudate on chemical analysis, comparable to the composition of the ascitic fluid. Bacteriological and cytological tests on both fluids were unremarkable.

TREATMENT AND COURSE

The right pleural effusion was presumed to be due to a hydrothorax from the ascites caused by portal hypertension associated with the PBC. Despite continuous diuretic treatment and thoracocentesis with albumin substitution every 3 days there was no improvement and implantation of a transjugular intrahepatic portosystemic stent shunt (TIPSS) was performed. This effectively lowered portal pressure and markedly improved the patient's condition so that further thoracocentesis were no longer necessary. 3 weeks after TIPSS implantation she was discharged in good condition. Radiography 3 weeks later demonstrated continued reduction in the hydrothorax.

CONCLUSION

Hydrothorax is a rare complication of liver cirrhosis. TIPSS implantation can provide lasting resolution and corresponding clinical improvement of a hydrothorax, especially in those conditions which are refractory to diuretic treatment and thoracocentesis.

Clinical, biochemical, and histological changes in hepatitis C virus infection-associated cryoglobulinemia

The most common extrahepatic manifestation of HCV infection is mixed cryoglobulinemia (MC). 62 unselected patients with chronic HCV infection were prospectively evaluated for the presence of cryoglobulinemia and associated clinical and biochemical parameters. Furthermore, a putative relationship between the HCV genotypes and cryoglobulinemia was tested. Histological features typical for HCV infection were comparatively analyzed in cases with and without cryoglobulinemia. Whether an intrahepatic Th2-response is responsible for the strong antibody production causing cryoglobulinemia was also examined. Cryoglobulins were detected in sera of 30 patients (approximately equal to 48%). Patients with cryoglobulinemia were on the average elder, showed an apparent longer duration of infection, and suffered more frequently from arthralgia, accompanied by a significant increase of total serum IgM concentration and rheumatoid factor activity. The HCV genotype distribution among patients with cryoglobulinemia was not different from that found in patients without cryoglobulinemia. In cases with cryoglobulinemia, an increased activity of chronic hepatitis and a higher grade of liver fibrosis was noted. The prevalence of HCV-typical histological lesions among all patients were: Portal lymphocytic aggregates (40%), bile duct damage (35%), steatosis (47%), and intracellular acidophilic bodies (29%). A significant correlation, however, could not be found between cryoglobulinemia and the presence of HCV-typical histological lesions. An intrahepatic Th2-response causing an increased antibody production could not be observed in cases with cryoglobulinemia.

[Extrahepatic manifestations of HBV and HCV infection]

Acute as well as chronic infections by HBV and HCV can be associated with extrahepatic disease. As in liver disease of non-viral etiology, several extrahepatic manifestations can be observed that are non-specific for HBV or HCV, e.g. those clinical signs and symptoms frequently encountered when cirrhosis of the liver is present. In addition, distinct clinical conditions have been described in which the unterlying liver disease is specifically due to HBV or HCV infection. In chronic HBV infection, glomerulonephritis (of the membranous and of the membranoproliferative type) and polyarteritis nodosa have been observed. The pathogenesis of both conditions involves the deposition of circulating immune complexes. Although controlled trials are lacking, interferon therapy appears to be beneficial. The use of immunosuppressive drugs and of plasmapheresis should probably be limited to the initial phase of treatment. In chronic HCV infection, mixed cryoglobulinemia (and ensuing systemic vasculitis) is a frequent extrahepatic manifestation. The clinical presentation might include the presence of purpura, arthralgias, weakness and renal involvement. Nowadays, HCV can be regarded as the etiological agent of a form of mixed cryoglobulinemia formerly considered to be 'essential'. In addition, an association to lymphoma has been postulated recently. Interferon alpha has been used for treatment with similar response rates as those observed in HCV-infected patients without cryoglobulinemia. Interestingly, the antiviral activity of interferon, e.g. normalization of transaminases and loss of serum HCV RNA, was closely related to the beneficial effect on cryoglobulinemia. An association of Sjögren's syndrome and of porphyria cutanea tarda to HCV infection (though claimed before) remains questionable. Serological markers of autoimmunity, e.g. antinuclear antibodies or anti-LKM-1, are present in many patients with chronic HCV infection. The clinical relevance of this latter observation appears low however, particularly since the decision for interferon treatment is hardly influenced by their presence.

Neuronal localization of presenilin-1 and association with amyloid plaques and neurofibrillary tangles in Alzheimer's disease

Mutations in the presenilin-1 (PS1) gene is a cause of early- onset familial Alzheimer's disease (AD). Endogenous PS1 is associated with the endoplasmic reticulum in the cell body of undifferentiated SH-SY5Y neuroblastoma cells. At early stages of neuronal differentiation in rat hippocampal culture, PS1 appears in all neuritic processes and in growth cones. In mature differentiated neurons, PS1 is concentrated in the somatodendritic compartment but is also present at lower levels in axons. A similar localization of PS1 is observed in vivo in neurons of the adult human cerebral cortex. In sporadic AD, PS1 appears in the dystrophic neurites of mature amyloid plaques and co-localizes with a subset of intraneuronal neurofibrillary tangles (NFTs). About 30% of hippocampal NFTs are labeled with a highly specific antibody to the PS1 C-terminal loop domain but not with an antibody to the PS1 N terminus. This observation is consistent with a potential association of the PS1 C-terminal fragment with NFTs, because PS1 is constitutively cleaved to N- and C-terminal fragments in neurons. These results suggest that PS1 is highly expressed and broadly distributed during early stages of neuronal differentiation, consistent with a role for PS1 in neuronal differentiation. Furthermore, the co-localization of PS1 with NFTs and plaque dystrophic neurites implicates a role for PS1 in the diverse pathological manifestations of AD.

Interferon-alpha treatment of hepatitis C virus-associated mixed cryoglobulinemia

BACKGROUND/AIMS

Chronic hepatitis C virus infection is frequently associated with mixed cryoglobulinemia. The efficacy of interferon-alpha treatment in the presence of cryoglobulinemia, particularly the rate of sustained responders, has not yet been well defined.

METHODS

Fifty-nine consecutive patients with chronic HCV infection were studied prospectively with regard to the presence of cryoglobulinemia and their biochemical and virological response to interferon-alpha2a therapy.

RESULTS

Cryoglobulins were detected in sera of 23 patients. For this latter group of patients, significant differences were found compared to the 36 patients without cryoglobulinemia, i.e. the prevalence of female sex was higher, the duration of liver disease was longer and distinctive laboratory abnormalities, e.g. higher rheumatoid factor activity, were noted as well as a higher prevalence of cirrhosis. The distribution of HCV genotypes and serum HCV RNA titers was similar in the two groups. Interferon-alpha treatment regimens were not different regarding mean cumulative dose and mean duration of therapy. The response to therapy was almost identical, i.e. 35% of patients with cryoglobulinemia showed a sustained response compared to 22% of patients without cryoglobulinemia. The percentages of patients showing a relapse or breakthrough were similar in both groups. Pre-treatment viremia levels were higher in non-responders compared to sustained responders. Non-responders appeared to be more frequent among patients infected with genotypes 1a and 1b, especially among male patients without cryoglobulinemia.

CONCLUSIONS

The presence of cryoglobulinemia per se in chronic HCV-infected patients does not adversely affect the outcome of interferon-alpha therapy, including the rate of sustained response.

Developmental regulation of presenilin-1 processing in the brain suggests a role in neuronal differentiation

Most cases of early-onset familial Alzheimer's disease are caused by mutations in the presenilin genes. Presenilin-1 (PS1) is subject to proteolytic cleavage resulting in the accumulation of N- and C-terminal fragments. In this report, we show that the proteolytic cleavage of PS1 is developmentally regulated in the brain. Low levels of full-length PS1 and higher levels of 30-kDa N-terminal and 20-kDa C-terminal fragments are identified at all developmental stages in the rat brain. However, in the adult brain, additional 36-kDa N-terminal and 14-kDa C-terminal fragments appear and become major PS1 species. Alternative N-terminal PS1 fragments also appear in the adult human brain, but are more heterogenous than in the rat brain. The alternative PS1 fragments are not detected at significant levels in rat or human peripheral tissues that express PS1. The alternative cleavage of PS1 is also detected in primary cultures of rat hippocampal neurons, but not in astrocytes, and is induced by neuronal differentiation. Furthermore, alternative PS1 cleavage is detected in rat PC12 cells and human neuroblastoma SH-SY5Y cells following induction of neuronal differentiation. These results suggest that an alternative pathway of PS1 proteolytic processing is induced in the brain by neuronal differentiation. PS1 may therefore play an important role in brain development and neuronal function, which may relate to the brain-specific pathological effects of PS1 mutations.

[Quality assurance in rheumatology. Evaluation of a team work model between general practitioners and a rheumatologist]

The intention of the project was to heighten the theoretical and practical skills of general practitioners in the care of patients with musceloskeletal problems. Six general practitioners and a rheumatologist participated. The rheumatologist joined the general practitioners at two health centres, which he visited on two occasions with an interval of six months. The patient and case history were presented by the local physician, and an additional historical and physical examination was performed by the rheumatologist. The physicians were trained in relevant examination techniques. The study was evaluated by means of questionnaires to the doctors and interviews with six patients. The theoretical knowledge of the general practitioners increased by an average of 23%. Both general practitioner and rheumatologist observed improvement in examination techniques. This parameter was not specifically evaluated. The patients appreciated the way in which they were treated. They found that the first and second line health care served as a smooth-working team. The cost of this project was low. The model is being continued at the request of the general practitioners.

Analysis of histopathological manifestations of chronic hepatitis C virus infection with respect to virus genotype

Hepatitis C virus (HCV) causes acute and often chronic hepatitis. On the basis of variations in nucleotide sequence, at least six genotypes and several subtypes have been identified. Histopathologically, chronic HCV infection is characterized by relatively mild hepatic inflammatory activity and a low degree of fibrosis, but hepatic lesions might be accompanied by bile duct damage, intraportal lymphoid aggregates, steatosis, or a combination of these manifestations. The histopathological lesions thus appear quite heterogeneous. To address the question of whether distinct histopathological manifestations are related to particular genotypes of HCV, 90 patients with chronic HCV infection were analyzed regarding histopathological features, biochemical liver parameters, demographic data, and virus genotype. The results revealed a significantly higher prevalence of both steatosis and bile duct lesions among patients infected by HCV type 3a compared to patients infected by types 1a or 1b. Furthermore, the data suggest interrelationships between virus genotype, patient's age, and a history of intravenous drug abuse. However, none of the histopathological manifestations were found to be related to a history of drug abuse. The data further corroborate the relationship of HCV type 1b infection to age, duration of disease, and the degree of fibrosis, respectively. Irrespective of HCV genotype, elevated serum ALT activity was shown to be associated with pronounced inflammatory activity or pronounced steatosis as well. Thus, the current data support the hypothesis that distinct genotypes of HCV appear to be associated with distinct manifestations of disease.

Distinct processing of endogenous and overexpressed recombinant presenilin 1

The presenilin 1 (PS1) gene has been identified by positional cloning. More than 30 mutations were detected in this gene which cosegregate with Alzheimer's disease (AD). Understanding their role in disease pathogenesis requires a characterization of the PS1 protein. We have generated a set of antibodies against the three major hydrophilic domains of the deduced amino acid sequence. Analyzing cultured cells and brain samples, we identified the endogenous PS1 polypeptide as well as amino- and carboxy-terminal fragments. These metabolites were much more abundant than the full-length molecule, indicating substantial processing. Overexpression of human PS1 markedly increased the full-length polypeptide but hardly altered the amount of the metabolites. Instead, additional proteolytic fragments appeared suggesting a different metabolism of the excess PS1, which may impede studies in transfected cells. Our results indicate a tight regulation of the endogenous PS1 metabolites. PS1 and its fragments are shown to be integral membrane proteins of the endoplasmic reticulum. The mechanisms regulating the generation of the metabolites, their potential function, and role in AD remain to be studied.

[TIPSS in the Budd-Chiari syndrome with portal vein thrombosis]

HISTORY AND CLINICAL FINDINGS

A 41-year-old woman, known for 10 month to have polycythaemia vera, developed severe right upper abdominal pain. The abdomen was tense from marked ascites and the liver enlarged by 18 cm in the mid-clavicular line.

INVESTIGATIONS

Serum bilirubin was slightly elevated to 2.2mg/dl, liver synthesis being much reduced (recalcifying time minimally 23%, albumin minimally 2.8 g/dl). Doppler sonography detected no flow in the right and middle hepatic veins, indicating Budd-Chiari syndrome. Portal vein flow was diminished.

TREATMENT AND COURSE

Heparin treatment had to be stopped because of heparin-associated type II thrombocytopenia and hirudin was substituted. Attempted lysis with a total of 100 mg r-tPA failed. As the patient's condition deteriorated a TIPSS was implanted to provide portal decompression. Incomplete portal vein thrombosis was demonstrated and worsened during the procedure until nearly complete occlusion. Local lysis treatment for 2 days with urokinase, 50,000-60,000 U/h, and two shunt revisions finally succeeded in completely dissolving the thrombus. Portocaval pressure fell from 32 to 21 mm Hg, and the size and function of the liver became almost normal and the ascites disappeared. Anticoagulation with a coumarin derivative was started and hydrocarbamide again given for recurrent thrombocytosis. The patient remained largely symptom-free one year after TIPSS.

CONCLUSION

This case demonstrates the effectiveness of TIPSS in Budd-Chiari syndrome, even in complicated portal vein thrombosis.

Crystal and molecular structure of unsubstituted and p-methoxy-substituted acetylbenzoylmethanatoboron difluoride

The crystal structures of two borines were solved by direct methods and refined by full-matrix least-squares procedure. 6-methyl-4-phenyl-1,3,2-(2

The crystal structure analysis of compound

Insulin-like growth factor-I serum concentrations and patterns of insulin-like growth factor binding proteins in patients with chronic liver disease

BACKGROUND/AIMS

Serum concentrations of insulin-like growth factor-I are decreased in liver cirrhosis. However, this growth factor is bound for the most part to specific binding proteins that are known to modulate biological actions. Plasma insulin-like growth factor binding proteins are predominantly synthesized in the liver.

METHODS

The effect of liver disease on basal and on growth hormone-stimulated serum concentrations of total and "free" insulin-like growth factor-I and on insulin-like growth factor binding protein patterns is reported. Sera were obtained from 20 patients with non-cirrhotic chronic liver diseases and from 20 patients with cirrhosis before and 24 h after a single subcutaneous dose of growth hormone. Samples were analyzed using radioimmunoassays, gel chromatography, ligand blotting and immunoblotting.

RESULTS

In cirrhosis, serum concentrations of total and "free" insulin-like growth factor-I were decreased, the binding protein pattern was changed profoundly showing a reduction in the 150 kD complex and an increase in the 30-40 kD complexes. Concentrations of binding protein-1 and -2 were increased, while that of binding protein-3 was decreased in cirrhosis. The response to growth hormone was blunted. These changes were related to the degree of liver dysfunction as assessed by the Child-Pugh classification.

CONCLUSIONS

A pathogenetic link of altered bio-availability of insulin-like growth factor-I to clinical characteristics of advanced liver disease, e.g. insulin resistance or skeletal muscle wasting, may be suggested by the present data.

Reform, not rhetoric: a critique of welfare policy and charting of new directions

Current changes in welfare policy are examined, and the likelihood that they will be unworkable or counterproductive is discussed. Based on knowledge and data from the articles in this special section, as well as other relevant research, policy and program recommendations are offered for welfare reform that would most effectively help poor women support themselves and their families.

Small-angle X-ray scattering reveals differences between the quaternary structures of oxygenated and deoxygenated tarantula hemocyanin

Small-angle X-ray scattering (SAXS) curves have been recorded for the oxygenated and deoxygenated states of the 4 x 6-meric hemocyanin from the tarantula Eurypelma californicum. A comparison of the curves shows that the quaternary structures of the two states are different by three criteria, which all indicate that the hemocyanin is less compact in the oxygenated compared to the deoxygenated form: (a) The radius of gyration is 8.65 +/- 0.05 nm for the deoxy- and 8.80 +/- 0.05 nm for the oxy-form. (b) The maximum particle dimension amounts to 25.0 +/- 0.5 nm for the deoxy- and to 27.0 +/- 0.5 nm for the oxy-form. (c) A dip in the intramolecular distance distribution function p(r) is more pronounced and shifted to larger distances in the oxy-form. The p(r) functions based on SAXS measurements were compared to p(r) functions deduced from published electron microscopical images of three different 4 x 6-meric hemocyanins from closely related species. The p(r) functions of SAXS and electron microscopy were similar in one case, whereas in the other two cases the distance between the two 12-meric half-molecules had to be changed by 1-1.5 nm to obtain good agreement. The differences between the p(r) functions of oxygenated and deoxygenated 4 x 6-meric tarantula hemocyanin are much larger than one would expect from a comparison of X-ray structures of the oxygenated and deoxygenated states of a closely related 6-meric hemocyanin. Thus, the conformational changes upon oxygenation occur at various levels of the quaternary structure, as postulated by hierarchical theories of allosteric interactions.

X-ray structure determination of a metastable state of carbonmonoxy myoglobin after photodissociation

The x-ray structure of carbon monoxide (CO)-ligated myoglobin illuminated during data collection by a laser diode at the wavelength lambda = 690 nm has been determined to a resolution of 1.7 A at T = 36 K. For comparison, we also measured data sets of deoxymyoglobin and CO-ligated myoglobin. In the photon-induced structure the electron density associated with the CO ligand can be described by a tube extending from the iron into the heme pocket over more than 4 A. This density can be interpreted by two discrete positions of the CO molecule. One is close to the heme iron and can be identified to be bound CO. In the second, the CO is dissociated from the heme iron and lies on top of pyrrole ring C. At our experimental conditions the overall structure of myoglobin in the metastable state is close to the structure of a CO-ligated molecule. However, the iron has essentially relaxed into the position of deoxymyoglobin. We compare our results with those of Schlichting el al. [Schlichting, I., Berendzen, J., Phillips, G. N., Jr., & Sweet, R. M. (1994) Nature 317, 808-812], who worked with the myoglobin mutant (D122N) that crystallizes in the space group P6 and Teng et al. [Teng, T. Y., Srajer, V. & Moffat, K. (1994) Nat. Struct. Biol. 1, 701-705], who used native myoglobin crystals of the space group P2(1). Possible reasons for the structural differences are discussed.

Down-regulation of free intracellular calcium in dissociated brain cells of aged mice and rats

Age-related changes in resting levels of the free intracellular calcium concentration ([Ca2+]i) as well as alterations of the rise in [Ca2+]i following depolarization have been investigated in acutely isolated cells of the mouse brain and of various regions of the rat brain. Resting [Ca2+]i as well as Ca2+ responses after depolarization were lower in brain cells of aged mice and in hippocampus and cortex cells, but not striatum or cerebellum cells of aged rats. It is concluded that the Ca2+ homeostasis is specially susceptible to the aging process in some brain regions only, resulting in a down regulation of [Ca2+]i probably as a consequence of an enhanced sensitivity of mechanisms regulating [Ca2+]i. This speculation was confirmed by an enhanced sensitivity of Ca(2+)-stimulated phospholipase C activity in the aging mouse brain. The alterations of the central Ca2+ homeostasis in the mouse and the rat were paralleled by comparable changes of [Ca2+]i in spleenocytes of both species in aging. The rise of [Ca2+]i after stimulation with the mitogen phytohemagglutinin (PHA) was significantly reduced in the plateau phase, which is maintained by Ca2+ influx mechanisms. Moreover, a reduced Ca2+ response was also found after stimulation of the cells with the Ca2+ ionophore A23187. The data may indicate that comparable disturbances of the Ca2+ homeostasis occur in central and peripheral cells and that these alterations mainly affect transmembraneous Ca2+ fluxes rather than Ca2+ release from intracellular stores. These alterations may be compensated under normal conditions. However, in situations of additional stress like ischemia or hypoglycemia, the preexisting alterations of Ca2+ homeostasis may result in a reduced capacity for adaptation. This assumption was supported by observations indicating that the down-regulation of [Ca2+]i after subchronic treatment with nimodipine (20 mg/kg, 14 days) was less in brain cells of aged than of young mice.

Lymphocytes and neutrophils as peripheral models to study the effect of beta-amyloid on cellular calcium signalling in Alzheimer's disease

According to the calcium hypothesis of brain aging, disturbances of free intracellular calcium homeostasis ([Ca2+]i) play a key role in pathology of Alzheimer's disease (AD). Recent data from neuronal tissue culture support the contribution of the beta-amyloid peptide (beta A) to neurodegeneration in AD, probably by disruption of the intracellular Ca2+ regulation. On the basis of this premise, we used peripheral blood cells to examine the role of beta A on Ca2+ signalling, not only to obtain an experimental approach to investigate these effects of beta A in man, but also to search for AD-specific alterations of the effects of beta A on Ca2+ signalling. This approach is based on observations indicating that the phytohemagglutinin (PHA)-induced Ca2+ response in circulating human lymphocytes of healthy volunteers is affected by beta A and its fragment 25-35 in a fashion similar to its effects on central neurons, whereas we found no effect of beta A on receptor-activated Ca2+ response in neutrophils. Therefore, we used human blood lymphocytes as peripheral model systems to search directly for AD-related abnormalities of Ca2+ regulation, for alterations of beta A effects on Ca2+ signalling and on membrane fluidity, and for possible changes of potassium channels. In accordance with our data in neutrophils, we were unable to identify any relevant change of the PHA-induced Ca2+ elevations in lymphocytes, which is not supporting the assumption of general alterations of cellular Ca2+ regulation in AD. On the other hand, the amplifying effect of beta A on Ca2+ signalling was significantly reduced in lymphocytes from AD patients. Moreover, Ca2+ responses to beta A25-35 were not different between early- and late-onset AD patients. Our findings indicate that the sensitivity of the lymphocyte for the effects of beta A is reduced in a high percentage of patients with probable or possible AD. As possible explanation we observed a similar reduction of the sensitivity of the lymphocyte membrane for the fluidity-decreasing properties of beta A. Finally, the inhibition of the PHA-induced Ca2+ response by tetraethylammonium (TEA) was lower in the AD group compared to aged controls. This could suggest the presence of a K+ channel dysfunction on AD lymphocytes, as it has been shown on skin fibroblasts of AD patients.

Region-specific downregulation of free intracellular calcium in the aged rat brain

Age-related changes in resting levels of the free intracellular calcium concentration ([Ca2+]i) as well as alterations of the rise in [Ca2+]i following depolarization have been investigated in acutely isolated brain cells of various regions of the rat brain. Characterization of the Ca2+ responses following KCl depolarization in the hippocampus, cortex, striatum, and cerebellum of young rats revealed significant regional differences in the basal [Ca2+]i level as well as in the KCl-induced rise in [Ca2+]i. However, there was no correlation between both parameters. Resting [Ca2+]i as well as Ca2+ responses after depolarization were lower in the hippocampus and cortex of the aged animals, but not in the striatum or cerebellum. It is concluded that the Ca2+ homeostasis in the first two regions is specially susceptible to the aging process, resulting in a downregulation of [Ca2+]i, probably as a consequence of an enhanced sensitivity of mechanisms regulating transmembraneous Ca2+ fluxes. The cellular Ca2+ homeostasis was altered in a comparable way in rat spleenocytes. The rise in [Ca2+]i in the aged animals following stimulation of lymphocytes with the mitogen phytohemagglutinin (PHA) was significantly reduced in the plateau phase, which is maintained by Ca2+ influx mechanisms. The data indicate that age-related disturbances of the cellular Ca2+ homeostasis may be present in different cell types and seem to affect mainly transmembraneous Ca2+ flux much more than intracellular Ca2+ release.