Generalized implicit fear associations in generalized anxiety disorder

BACKGROUND

Cognitive schema theories of anxiety postulate that higher-level cognitive processes such as attention and memory are guided by underlying distorted fear associations. While numerous studies investigated these disorder-specific, biased processes, hardly any research addressed the underlying schemata themselves. In particular, no study has ever addressed implicit fear associations in Generalized Anxiety Disorder (GAD). In addition, no study has ever experimentally investigated the clinical observation that in GAD, patients' worry processes seem to be triggered by a broad range of materials, even by neutral or positive stimuli.

METHODS

We used a Single Target Implicit Association Task (STIAT) to investigate implicit associations and stimulus generalization with clearly negative worry-related words (e.g., cancer, bankruptcy) and neutral words that are only indirectly related to worry topics (e.g., doctor, bank). Participants were 39 GAD patients and 23 healthy controls.

RESULTS

In line with our expectations, both groups showed negative implicit associations with negative target words, and only GAD patients also associated neutral words with negative attributes.

CONCLUSIONS

These results support the hypothesis that GAD patients' fear associations generalize to stimuli that are only peripherally related to the core of their worries.

Three Indirect Tasks Assessing Implicit Threat Associations and Behavioral Response Tendencies

Anxiety disorders are characterized by biased implicit threat associations, which can be measured by indirect reaction time tasks. These tasks might provide a useful tool in the assessment of individual diagnoses and therapeutic changes. However, sufficient psychometric properties of the applied tasks are a prerequisite for these applications. Therefore, we comparatively investigated the reliability and validity of an Extrinsic Affective Simon Task (EAST), an Approach-Avoidance Task (AAT), and an Affective Priming Task (APT) by presenting the same tasks twice within 1 week. Data show retest reliabilities of around r = .42 for the EAST, r = .35 for the AAT, and r = .63 for the APT. Internal consistencies varied between .44 and .49 for the EAST, .66 and .70 for the AAT, and .53 and .76 for the APT. Validity correlations with self-report questionnaires ranged between r = .43 and r = .59, being lowest for the EAST and highest for the AAT. We argue that while these instruments might not be applicable to individual diagnostics yet, they are sufficiently reliable and valid to be used in the assessment of group differences.

Effect of acute antidepressant administration on negative affective bias in depressed patients

OBJECTIVE

Acute administration of an antidepressant increases positive affective processing in healthy volunteers, an effect that may be relevant to the therapeutic actions of these medications. The authors investigated whether this effect is apparent in depressed patients early in treatment, prior to changes in mood and symptoms.

METHOD

In a double-blind, placebo-controlled, between-groups randomized design, the authors examined the effect of a single 4-mg dose of the norepinephrine reuptake inhibitor reboxetine on emotional processing. Thirty-three depressed patients were recruited through primary care clinics and the community and matched to 31 healthy comparison subjects. Three hours after dosing, participants were given a battery of emotional processing tasks comprising facial expression recognition, emotional categorization, and memory. Ratings of mood, anxiety, and side effects were also obtained before and after treatment.

RESULTS

Depressed patients who received placebo showed reduced recognition of positive facial expressions, decreased speed in responding to positive self-relevant personality adjectives, and reduced memory for this positive information compared to healthy volunteers receiving placebo. However, this effect was reversed in patients who received a single dose of reboxetine, despite the absence of changes in subjective ratings of mood or anxiety.

CONCLUSIONS

Antidepressant drug administration modulates emotional processing in depressed patients very early in treatment, before changes occur in mood and symptoms. This effect may ameliorate the negative biases in information processing that characterize mood and anxiety disorders. It also suggests a mechanism of action compatible with cognitive theories of depression.

How preferential is the preferential encoding of threatening stimuli? Working memory biases in specific anxiety and the Attentional Blink

Temporal visual working memory (VWM) biases in spider anxiety were studied with an Attentional Blink paradigm. In Experiment 1, participants viewed pictures sequentially presented at rates of 80 ms and were instructed to memorize two target pictures. We varied time between targets and valence of the second target (neutral: mushroom, positive: blossom, negative: spider). In Experiment 2, spider fearfuls and non-anxious controls (both without snake anxiety) participated. Here we tested two negative targets: disorder-related spiders and disorder-irrelevant snakes. Both positive and negative items were memorized more successfully than neutral targets. Spiders were preferentially recalled by spider fearfuls compared to non-anxious controls, implying temporal VWM biases in spider anxiety. This advantage for threat was not related to a disruption of the encoding of non-threatening targets presented before the threat item.

Multipotent cells of monocytic origin improve damaged heart function

Recently, we generated cells with multipotent properties from blood monocytes that in vitro differentiate into various somatic cell types. This experimental study investigated whether these programmable cells of monocytic origin (PCMO) succeed to restore left ventricular function after myocardial infarction (MI). PCMO were generated from monocytes by exposition to RPMI medium containing M-CSF and IL-3 for 6 days. MI was induced in female Lewis rats ligating the left coronary artery. PCMO of male Lewis donors were injected either intramyocardially (i.my.) or intravenously (i.v.) 24 h or 6 days post-infarction. Hemodynamic assessment after 60 days demonstrated significant improvement of left ventricular function following i.my. transplantation of PCMO as well as early (24 h post-infarction) i.v. application while nonmodulated monocytes failed to restore heart function. The Y-chromosome-specific SRY gene of male donor PCMO was detected exclusively in infarcted hearts of animals, which demonstrated improved cardiac function. Subdivision of infarcted hearts by microdissection localized the SRY gene-containing department to the left ventricle adjacent to the infarcted area whereas the right ventricle remained negative. Successful generation of PCMO in access numbers allows their autologous use as a new additive treatment for early restoration of cardiac function after MI.

Spiders crawl easily through the bottleneck: Visual working memory for negative stimuli

The special status of spiders in the attentional bottleneck and visual working memory (VWM) was studied. 23 spider-fearfuls (SF) and 23 non-anxious controls (NACs) participated in a serial VWM-task. Each trial showed a 4 x 4 matrix of images and 5 of these were subsequently cued for 150 ms each. Afterwards, one of the 16 displayed images was hidden and probed. The spider image was included in the string of 5 cued images, among the 11 uncued items, or not at all. For both groups, memory was better for cued spiders than for other cued items. SFs also showed improved memory for uncued spiders. The relevance of the results for theories of attention and cognitive models of phobias are discussed.

Why don't we see changes?: The role of attentional bottlenecks and limited visual memory

Seven experiments explore the role of bottlenecks in selective attention and access to visual short-term memory in the failure of observers to identify clearly visible changes in otherwise stable visual displays. Experiment One shows that observers fail to register a color change in an object even if they are cued to the location of the object by a transient at that location as the change is occurring. Experiment Two shows the same for orientation change. In Experiments Three and Four, attention is directed to specific objects prior to making changes in those objects. Observers have only a very limited memory for the status of recently attended items. Experiment Five reveals that observers have no ability to detect changes that happen after attention has been directed to an object and before attention returns to that object. In Experiment Six, attention is cued at rates that more closely resemble natural rates and Experiment Seven uses natural images. Memory capacity remains very small (<4 items).

[Acute coronary syndrome after diclofenac induced coronary spasm]

We report about a 67-year old man, who was submitted to our clinic with acute coronary syndrome. The cardiac catheterization showed a proximal thrombus in the left anterior descending (LAD). The other coronary arteries did not have significant lesions. After percutaneous transluminal coronary angioplasty with stent-implantation into the proximal LAD the patient remained clinically stable. Cardiac enzymes confirmed no myocardial necrosis. Three days after the acute coronary syndrome the patient developed a podagra, which was treated with colchicinum, diclofenac and local cooling. Five hours after initial therapy the patient developed severe symptoms of angina pectoris and electrocardiographical signs of an acute posterior and anterior myocardial infarction. Immediate coronary angiography demonstrated extended vasospasm of the right coronary artery. Intracoronary application of verapamil and nitroglycerin resolved the coronary spasm. The patient reported about a self-indicated application of diclofenac six hours before hospital admission. This case demonstrates that oral application of diclofenac can provoke coronary vasospasm.

Speeded Detection and Increased Distraction in Fear of Spiders: Evidence From Eye Movements

Anxiety patients exhibit attentional biases toward threat, which have often been demonstrated as increased distractibility by threatening stimuli. In contrast, speeded detection of threat has rarely been shown. Therefore, the authors studied both phenomena in 3 versions of a visual search task while eye movements were recorded continuously. Spider-fearful individuals and nonanxious control participants participated in a target search task, an odd-one-out search task, and a category search task. Evidence for disorder-specific increased distraction by threat was found in all tasks, whereas speeded threat detection did not occur in the target search task. The implications of these findings for cognitive theories of anxiety are discussed, particularly in relation to the concept of disengagement from threat.

Diabetes and Cardiovascular Risk Evaluation and Management in Primary Care: Progress and Unresolved Issues

This review highlights established and more recently recognized risk factors for coronary heart disease (CHD) relevant for patients seen in primary care, emphasizing the key role of diabetes mellitus type 2. Recent trends in risk factor research as well as current methods of risk stratification, and new systemic markers are discussed. Beyond the need for more forceful public health strategies to improve early recognition and intervention, the necessity of an integrated comprehensive investigation of the overall characteristics of cardiovascular disease, especially in primary care patients as a prerequisite for future concerted actions is pointed out. Based on this, a large-scale epidemiological investigation focusing on CHD and diabetes in the primary care sector is suggested.

[Bland-White-Garland syndrome in an adult]

We report about a 47-year-old woman, who presented with a history of cardiac failure. Echocardiography showed an impaired left ventricular function, clinically significant mitral regurgitation and pulmonary hypertension. Diagnosis of a Bland- White-Garland syndrome was made by coronary angiography. Subsequent therapy consisted of ligation of the anomalus origin of the left coronary artery, implantation of a Mammaria interna graft to the left coronary artery and replacement of the mitral valve by a mechanical prosthesis. One year after operation, left ventricular function was still impaired. At a 3-year follow-up, left ventricular function improved continuously.

Tissue-specific expression of a rat renin transcript lacking the coding sequence for the prefragment and its stimulation by myocardial infarction

An alternative transcript of the rat renin gene was recently characterized in the adrenal gland, in addition to the known messenger RNA (mRNA) coding for preprorenin. In the alternative transcript, exon 1 is replaced by exon 1A, a domain originating in intron 1. The reading frame of this mRNA, termed exon 1A-renin transcript, codes for a truncated prorenin that presumably remains intracellular, in contrast to preprorenin, which is targeted to the secretory pathway by its prefragment. We here demonstrate the tissue-specific regulation of expression of both transcripts by RT and PCR. In many tissues both transcripts are present, for example in the adrenal gland, spleen, liver, and hypothalamus. In some organs, however, only one of the renin mRNAs is found. In the kidney only the full-length mRNA coding for preprorenin is detected. In the heart exclusively the exon 1A-mRNA is expressed, but not the preprorenin transcript. After myocardial infarction, which is known to activate the intracardiac renin-angiotensin system, expression of exon 1A-renin mRNA in the left ventricle was stimulated about 4-fold, compared with that in sham-operated animals, whereas no mRNA corresponding to preprorenin was detectable. These findings may have implications for the current concepts of local extrarenal renin-angiotensin systems, as they provide the molecular basis for a possible intracellular function of renin and exclude a role for locally produced secretory renin in the heart.

Expression of angiotensin AT(1) and AT(2) receptors in adult rat cardiomyocytes after myocardial infarction. A single-cell reverse transcriptase-polymerase chain reaction study

The effector hormone of the renin-angiotensin system, angiotensin II, plays a major role in cardiovascular regulation. In rats, both angiotensin receptor subtypes, AT(1) and AT(2), are up-regulated after myocardial infarction but previous studies failed to identify the cell types which express the AT(2) receptor in the heart. To address this question we established a single-cell reverse transcriptase-polymerase chain reaction for AT(1) and AT(2) receptors to determine whether these receptor subtypes are expressed in adult rat cardiomyocytes before and 1 day after myocardial infarction. By laser-assisted cell picking, section profiles of single cells without genomic DNA contamination were isolated. After dividing samples into two identical aliquots, polymerase chain reaction amplification for AT(1) and AT(2) receptors was carried out and polymerase chain reaction products were subjected to gel electrophoresis. Compared to control (n = 4) and sham-operated animals (n = 4), the number of cardiomyocytes expressing the AT(1) receptor mRNA 1 day after myocardial infarction (n = 4) was not changed (42% and 33% versus 45%, respectively). On the other hand, AT(2) receptor mRNA was expressed in 8% and 13%, respectively, of cardiomyocytes gained from control (n = 4) and sham-operated animals (n = 4) and in 14% isolated after myocardial infarction (n = 4). These results demonstrate for the first time that the AT(2) receptor is expressed in adult cardiomyocytes in vivo. They further suggest that the previously observed up-regulation of cardiac AT(1) and AT(2) receptors after myocardial infarction involves cell types other than cardiomyocytes.

Opposite regulation of brain and C-type natriuretic peptides in the streptozotocin-diabetic cardiopathy

C-type natriuretic peptide (CNP), a recent addition to the family of natriuretic peptides including atrial and brain natriuretic peptide (ANP, BNP), is believed to be an endothelium-derived vasodilator and to have an antimitotic effect. ANP and BNP concentrations are increased in conditions such as congestive heart failure, but cardiac CNP concentrations have not been investigated in this connection. Diabetes mellitus also involves myocardial dysfunctions without coronary artery disease or systemic hypertension. We therefore investigated the cardiac expression of CNP mRNA compared with that of BNP mRNA in streptozotocin (STZ)-diabetic rats. STZ- diabetic male Wistar rats (n=6) were studied in comparison with controls (n=6). The animals were characterised by their mean arterial blood pressure and plasma glucose concentrations. After extraction of total cardiac RNA, a specific cDNA probe of BNP was used for northern blot analysis, whereas myocardial CNP expression was analysed by an RNase-protection assay. Twelve weeks after diabetes was induced, the rats were normotensive (96.4+/-2.0 compared with 95.1+/-1.9 mmHg) and hyperglycaemic (615+/-61 compared with 165+/-21 mg/dl; P<0.001). Left ventricular pressure was significantly impaired (76.8+/-6.4 compared with 51.2+/-3.6 mmHg). STZ-diabetic rats had a 3.2-fold increase in cardiac BNP expression compared with controls. In contrast, cardiac CNP mRNA concentrations were decreased 2.6-fold. CNP seems to be downregulated like other peptides with antimitotic and vasodilator activities (nitric oxide, prostacyclin, kinins). This may contribute to cardiac dysfunction in diabetes mellitus and suggests that stimulation of CNP expression could provide cardiac protection in such cases.

Cardioprotective effects of the Na(+)/H(+)-exchange inhibitor cariporide in infarct-induced heart failure

OBJECTIVE

We investigated the effect of chronic treatment with the new Na(+)/H(+)-exchange inhibitor, cariporide, on cardiac function and remodelling 6 weeks after myocardial infarction (MI) in rats.

METHODS

Treatment with cariporide was commenced either 1 week pre or 30 min, 3 h, 24 h or 7 days after ligation of the left ventricular artery and was continued until haemodynamic parameters were obtained 6 weeks after MI in conscious rats.

RESULTS

Compared to sham animals, untreated MI-controls developed pronounced heart failure after 6 weeks. Basal left ventricular end-diastolic pressure (in mmHg) was reduced in the groups in which cariporide was started 1 week pre (16.0+/-1.7) or 30 min (12.5+/-1.1), 3 h (11.8+/-1.0) and 24 h (13.0+/-2.5) after MI compared to untreated MI-controls (22. 4+/-1.5; P<0.01). Basal myocardial contractility (in 1000 mmHg/s) was only increased when treatment was initiated after 30 min (9. 0+/-0.7), 3 h (8.5+/-0.3) and 24 h (8.0+/-0.7) compared to untreated MI-controls (5.8+/-0.7; P<0.05-0.01). Infarct size (in % of left ventricular circumference) was 40.0+/-2.1 in MI-controls and was decreased when treatment was begun after 30 min (32.6+/-2.7) or 3 h (32.4+/-2.3) (P<0.05). In animals, in which cariporide was started 3 h after induction of MI, heart weight/body weight ratio was significantly decreased, indicating reduced cardiac hypertrophy. When treatment started 7 days after MI, cariporide did not exert any beneficial actions on structural and functional cardiac parameters.

CONCLUSION

Our results show for the first time that chronic treatment with the Na(+)/H(+)-exchange inhibitor cariporide engendered marked cardioprotective effects when commenced before and up to 24 h after MI. The optimal time for the start of treatment was between 30 min and 3 h post MI.

Effects of a novel angiotensin AT(1) receptor antagonist, HR720, on rats with myocardial infarction

Cardiac remodeling after myocardial infarction is associated with impaired ventricular function and heart failure and has important implications for survival. The purpose of the present study was to assess the effects of chronic treatment with a novel angiotensin AT(1) receptor antagonist 2-butyl-4-(methylthio-)-1-[[2'[[[(propylamino)carbonyl]amino]sulfonyl ](1,1'-biphenyl)-4-yl]methyl]-1H-imidazole-5-carboxylate (HR720), on cardiac remodeling and left ventricular dysfunction in a rat model of large myocardial infarction. Rats were subjected to permanent ligation of the left coronary artery and were treated for six weeks with placebo or HR720 (3 mg/kg/day) initiated 24 h after surgery. Sham-operated rats served as normal controls. Mean arterial blood pressure, the maximum rate of rise of the left ventricular systolic pressure (dP/dt(max)), left ventricular end-diastolic pressure, left ventricular inner diameter and circumference, septal thickness, left ventricular collagen content and heart weight were measured at the end of the treatment. HR720 treatment versus placebo attenuated the cardiac hypertrophy (heart weight/body weight: 2.88+/-0.08 mg/g vs. 3.16+/-0.09 mg/g, P<0.05), reduced interstitial collagen content (3. 47+/-0.28% vs. 5.25+/-0.45%, P<0.01), limited infarct size (33.0+/-3. 0% vs. 41.5+/-2.3%, P<0.05), decreased left ventricular end-diastolic pressure (13.7+/-2.2 vs. 21.4+/-1.6 mm Hg, P<0.01) and improved dP/dt(max) (9000+/-430 vs. 6000+/-840 mm Hg/s, P<0.05). The present results demonstrate that chronic treatment with the angiotensin AT(1) receptor antagonist HR720 can limit infarct size, partially prevent cardiac hypertrophic remodeling and improve left ventricular function in rats with myocardial infarction.

Functional, biochemical, and molecular investigations of renal kallikrein-kinin system in diabetic rats

A reduction of renal kallikrein has been found in non-insulin-treated diabetic individuals, suggesting that an impaired renal kallikrein-kinin system (KKS) contributes to the development of diabetic nephropathy. We analyzed relevant components of the renal KKS in non-insulin-treated streptozotocin (STZ)-induced diabetic rats. Twelve weeks after a single injection of STZ, rats were normotensive and displayed hyperglycemia, polyuria, proteinuria, and reduced glomerular filtration rate. Blood bradykinin (BK) levels and prekallikrein activity were significantly increased compared with controls. Renal kallikrein activity was reduced by 70%, whereas urinary BK levels were increased up to threefold. Renal kininases were decreased as indicated by a 3-fold reduction in renal angiotensin-converting enzyme activity and a 1.8-fold reduction in renal expression of neutral endopeptidase 24.11. Renal cortical expression of kininogen and B2 receptors was enhanced to 1.4 and 1. 8-fold, respectively. Our data suggest that increased urinary BK levels found in severely hyperglycemic STZ-diabetic rats are related to increased filtration of components of the plasma KKS and/or renal kininogen synthesis in combination with decreased renal kinin-degrading activity. Thus, despite reduced renal kallikrein synthesis, renal KKS is activated in the advanced stage of diabetic nephropathy.

Myocardial expression of rat bradykinin receptors and two tissue kallikrein genes in experimental diabetes

To characterize the role of the kallikrein-kinin system in diabetic cardiopathy, we studied the effect of streptozotocin (STZ) on the regulation of the myocardial bradykinin (BK) receptors, the B1 and B2 type, and two tissue kallikrein genes, rat kallikrein 1 (rKLK1) and rKLK7, in severely hyperglycemic rats. Experiments were performed in STZ-induced diabetic male Wistar rats (n = 7) and compared to controls (n = 7). After extraction of myocardial total RNA, specific oligonucleotides were used to generate reverse transcription PCR (RT-PCR) products from myocardial rKLK1 and rKLK7 mRNA. Southern blot analyses of these RT-PCR products were hybridized with appropriate gene-specific oligonucleotide probes. Myocardial B1 and B2 receptor expression were analyzed by RNase protection assays using specific probes from the coding region of the receptor genes. Twelve weeks after diabetes induction, the rats were normotensive and hyperglycemic and polyuric. We observed an impairment of the main myocardial kinin-forming enzymes, indicated by a reduction of the expression of both, rKLK1 and rKLK7. At this time the myocardial expression of the B1 receptor was not detectable in either group. Thus, the B1 receptor does not play a regulatory role in either the healthy or in STZ-diabetic heart. In contrast, the B2-receptor expression was detectable but did not differ significantly in either group. The reduced synthesis of myocardial tissue KLK implies a reduced capacity to generate BK in diabetic rats. This reduction is not compensated by elevated BK receptor levels. We suggest that alterations of the KKS may contribute to myocardial dysfunction in diabetes mellitus.

Upregulation of osteopontin expression in renal cortex of streptozotocin-induced diabetic rats is mediated by bradykinin

The model of streptozotocin (STZ)-induced diabetes in Wistar rats was used to study the expression of osteopontin during development of diabetic nephropathy. Diabetes was confirmed by serum glucose levels exceeding 16 mmol/l during the experimental period of 12 weeks. During this period of time, diabetic nephropathy developed, as characterized by a reduced glomerular filtration rate (2.7 +/- 0.3 ml/min in controls vs. 1.7 +/- 0.1 ml/min in diabetic rats) and proteinuria (8.3 +/- 1.7 mg/24 h in controls vs. 22.0 +/- 4 mg/24 h in diabetic rats). Northern blot analysis revealed a time-dependent upregulation of renal cortical osteopontin expression reaching 138 +/- 6% of control levels after 2 weeks and 290 +/- 30% (mean +/- SE, n = 6-9) after 12 weeks. By immunostaining, the increased osteopontin expression could be located to the tubular epithelium of the renal cortex. Chronic treatment of animals with ramipril (3 mg/kg) during the 12-week experimental period led to a further increase in osteopontin mRNA expression in diabetic animals, amounting to 570 +/- 73% (mean +/- SE, n = 6) of controls. Increased levels of osteopontin were not associated with accumulation of monocyte/macrophages that were identified by the cell type specific monoclonal antibody ED-1. The increased osteopontin expression in ramipril-pretreated rats was abolished by application of the bradykinin B2-receptor antagonist, icatibant (0.5 mg/kg). In addition, increased osteopontin expression in diabetic rats, which did not receive any treatment after STZ injection, could as well be reduced by icatibant given for the final 2 weeks of the experimental period. These data suggest that a strong bradykinin B2-receptor-mediated upregulation of osteopontin occurs during the pathogenesis of experimental diabetic nephropathy in rats.

Renal expression of two rat kallikrein genes under diabetic conditions

OBJECTIVE

We have reported that bradykinin (BK) excretion is increased in severely diabetic rats, independent of the activity of the main renal kinin-forming enzyme, true kallikrein (KLK). To further investigate the relationship between renal BK excretion and renal KLK in diabetes we studied the regulation of the renal kallikrein-like gene, rat kallikrein 7 (rKLK7), as well as of the KLK encoding gene, rKLK1, in streptozotocin-induced (STZ) diabetic rats.

METHODS

Experiments were performed in STZ-induced diabetic male Wistar rats and their non-diabetic controls (n = 7 each group). Twelve weeks after STZ injection, urinary KLK activity, glomerular filtration rate and total protein excretion were determined. After extraction of total renal cortical RNA, specific oligonucleotides were used to generate a reverse transcription-polymerase chain reaction (RT-PCR) products of renal cortical rKLK1 and rKLK7 messenger (m)RNA. Southern blot analysis of these RT-PCR products were hybridized with appropriate gene-specific oligonucleotide probes.

RESULTS

After 12 weeks, the rats showed hyperglycemia, proteinuria and a reduced glomerular filtration rate. Renal kininogenase was reduced, as indicated by a reduction in the expression of rKLK1, as well as of the KLK-related gene, rKLK7.

CONCLUSIONS

Our data show that the expression of the two principal renal KLK genes is downregulated in the renal cortex of STZ-diabetic rats. We suggest that under severe diabetic conditions the rise in urinary BK excretion is not related to activation of the renal kinin-forming enzyme system.

Bradykinin excretion is increased in severely hyperglycemic streptozotocin-diabetic rats

The renal kallikrein-kinin system (KKS) was studied in pair-fed streptozotocin (STZ)-induced diabetic rats and compared with age-matched controls. Twelve weeks after STZ injection, rats were normotensive, showed hyperglycemia, proteinuria, polydipsia and reduced glomerular filtration rate (GFR) and body weight. The activities of urinary prekallikrein (PKLK) and kallikrein (KLK) were reduced accompanied by an up to 3-fold increase of bradykinin (BK) excretion compared to controls. The increased BK excretion suggests that the renal KKS in STZ-diabetes is activated and that the reduction in urinary PKLK and KLK activity may be due to an increased consumption of these enzymes or to a negative feedback mechanism. The stimulation of the renal KKS in STZ-diabetes could reflect an attempt of the organism to balance glomerular hypertension.

The functional effects of biotinylation of anti-angiotensin-converting enzyme monoclonal antibody in terms of targeting in vivo

The effect of modification with biotin N-hydroxysuccinimide ester of mouse monoclonal antibody to angiotensin-converting enzyme, anti-ACE Mab 9B9, on its targeting to endothelial cells has been studied in vitro and in vivo. By in vitro assay, Mab 9B9 biotinylated at a biotin/IgG molar ratio in reaction mixture (B/IgG ratio) of 0.7-2.2 bound streptavidin monovalently and retained antigen-binding capacity. Mab 9B9 biotinylated at a B/IgG ratio of 20 and higher bound streptavidin polyvalently. Extensive biotinylation (B/IgG ratio of 60 and higher) led to dramatic reduction of Mab 9B9 Ag-binding capacity and to reduction of Mab 9B9 recognition by goat polyclonal antibody to mouse IgG. Radiolabeled Mab 9B9 biotinylated at a B/IgG ratio of 6 (b6-Mab 9B9) bound effectively to cultured vascular endothelium, with affinity characteristics similar to nonbiotinylated Mab 9B9. Endothelial cells internalized both Mab 9B9 and b6-Mab 9B9 to the same extent (60% internalization at 3 h incubation at 37 degrees C). Degradation of cell surface-associated Mab 9B9 or b6-Mab 9B9 was very low (< 1% as measured by TCA solubility of radiolabel). In contrast, degradation of internalized b6-Mab 9B9 was more profound than that of Mab 9B9 (20 +/- 3% vs 6 +/- 1%, P < 0.01). After injection in rats, radiolabeled b6-Mab 9B9 had a biodistribution pattern similar to that of radiolabeled Mab 9B9. Both preparations effectively accumulated in the lung (15-20% of injected dose/g of tissue vs 2% of injected dose/g of blood).(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of sequential embryo transfer on pregnancy following in vitro fertilization]

In this study, the influence of sequential embryo transfers in an in-vitro fertilisation programme was examined. After in-vitro fertilisation, a maximum of 6 fertilised oocytes were cultured. In cases with more than 6 fertilised oocytes, the rest was cryopreserved in the pronucleus stage. At day 2 after an oocytes retrieval, three embryos with the best morphological appearance were replaced and the remaining embryos (1-3) were cultured for further 3 days. At day 5 after oocytes collection, second a embryo transfer was performed, if one of these embryos had reached the blastocyst stage. In a total of 106 patients, 40 pregnancies (38%) could be observed. No statistical difference in the pregnancy rate could be seen between the group with a second embryo transfer (n = 38; 42%) and the group without second transfer (n = 68; 35%). The incidence of multiple pregnancy was not statistically different between both group and no high-rank multiple pregnancy (greater than Triplete) were observed. Out of 300 cultured embryos, only 59 embryos (17%) reached the blastocyst stage. In the group, in which a second embryo transfer was performed, 22 patients received one blastocyst and 13 patients two blastocysts during the second transfer. The second transfer did not have a significant effect on the pregnancy rate in this series. The most important factor for the induction of pregnancy seems to be the quality of the embryos transferred on day 2 following oocyte retrieval.

Dynamics of the cytoskeleton in Amoeba proteus. III. Influence of microinjected antibodies on the organization and function of the microfilament system

Affinity-purified antibodies against actin, myosin, alpha-actinin and vinculin cross-reacted with corresponding proteins from Amoeba proteus in immunoblotting experiments. Antibody staining of cells fixed during locomotion revealed different distribution patterns with a local concentration of anti-actin in the intermediate and of anti-myosin in the uroid region. Anti-alpha-actinin labeled a thin layer at the internal face of the plasma membrane, whereas anti-vinculin was distinctly concentrated at the base of advancing pseudopodia. Microinjection of different control solutions or antibodies against actin, myosin and alpha-actinin neither influenced the normal morphology and motile activity of amoebae nor changed the cellular distribution pattern of complementary antigens. However, antibodies against vinculin disorganized controlled locomotion and altered the spatial morphology of the microfilament system as well as the localization of the vinculin antigen thus pointing to a function of this protein in adhesion and locomotion of A. proteus. The results of the present paper show similarities to observations on mammalian tissue culture cells.

Cryopreservation of human oocytes

Three different methods were used for freezing human excess oocytes (320 frozen, 205 thawed) in our IVF programme and the results of these methods were compared. A high fertilization rate (75%) could be achieved after thawing, using 1,2 propanediol as a cryoprotectant. Polyploidy rates of 20% and 40% were observed using DMSO and 1,2-propanediol as cryoprotectants, respectively. Using the ultracooling method, the survival rate was poor (4%).