Corneal limbal microenvironment can induce transdifferentiation of hair follicle stem cells into corneal epithelial-like cells

The aim of this study was to investigate the transdifferentiation potential of murine vibrissa hair follicle (HF) stem cells into corneal epithelial-like cells through modulation by corneal- or limbus-specific microenvironmental factors. Adult epithelial stem cells were isolated from the HF bulge region by mechanical dissection or fluorescence-activated cell sorting using antibodies to alpha6 integrin, enriched by clonal expansion, and subcultivated on various extracellular matrices (type IV collagen, laminin-1, laminin-5, fibronectin) and in different conditioned media derived from central and peripheral corneal fibroblasts, limbal stromal fibroblasts, and 3T3 fibroblasts. Cellular phenotype and differentiation were evaluated by light and electron microscopy, real-time reverse transcription-polymerase chain reaction, immunocytochemistry, and Western blotting, using antibodies against putative stem cell markers (K15, alpha6 integrin) and differentiation markers characteristic for corneal epithelium (K12, Pax6) or epidermis (K10). Using laminin-5, a major component of the corneo-limbal basement membrane zone, and conditioned medium from limbal stromal fibroblasts, clonally enriched HF stem and progenitor cells adhered rapidly and formed regularly arranged stratified cell sheets. Conditioned medium derived from limbal fibroblasts markedly upregulated expression of cornea-specific K12 and Pax6 on the mRNA and protein level, whereas expression of the epidermal keratinocyte marker K10 was strongly downregulated. These findings suggest that adult HF epithelial stem cells are capable of differentiating into corneal epithelial-like cells in vitro when exposed to a limbus-specific microenvironment. Therefore, the HF may be an easily accessible alternative therapeutic source of autologous adult stem cells for replacement of the corneal epithelium and restoration of visual function in patients with ocular surface disorders.

Safety profile of topical VEGF neutralization at the cornea

PURPOSE

Bevacizumab eyedrops inhibit corneal neovascularization. The purpose of this study was to analyze the safety profile of VEGF-A neutralization at the ocular surface.

METHODS

Bevacizumab eyedrops (5 mg/mL) and an antimurine VEGF-A antibody (250 microg/mL) were applied to normal murine corneas five times a day for 7 and 14 days. Subsequently, corneas were analyzed for morphologic changes by light and electron microscopy. In a mouse model of corneal epithelial abrasion, the effects of topically applied anti-VEGF antibodies on epithelial wound healing were analyzed: the treatment group received bevacizumab (5 mg/mL) or the antimurine VEGF-A antibody (250 microg/mL) as eyedrops, and the control group received an equal volume of saline solution. After 12, 18, and 24 hours, corneas were photographed in vivo with and without fluorescein staining for morphometry. Afterwards the mice were killed, and eyes were removed for histology, immunohistochemistry with Ki67/DAPI, and electron microscopy. The effect of midterm anti-VEGF therapy on corneal nerve density was assessed by staining corneas treated with an FITC-conjugated anti-neurofilament antibody and morphometric analysis.

RESULTS

Murine corneas treated with two different types of anti-VEGF antibody eyedrops did not show obvious corneal morphologic changes at the light and electron microscopic levels. Furthermore, anti-VEGF antibody eyedrops had no significant impact on the wound healing process after corneal epithelial injury or on normal murine corneal nerve fiber density.

CONCLUSIONS

Topical neutralization of VEGF-A at the corneal surface does not have significant side effects on normal corneal epithelial wound healing, normal corneal integrity, or normal nerve fiber density. Therefore, anti-VEGF eyedrops seem to be a relatively safe option to treat corneal neovascularization.

Blockade of VEGFR3-signalling specifically inhibits lymphangiogenesis in inflammatory corneal neovascularisation

PURPOSE

Inflammatory corneal hem- and lymphangiogenesis occurring both prior to as well as after penetrating keratoplasty significantly increase the risk for subsequent immune rejections. The purpose of this study was to analyze whether the blocking anti-VEGFR3 antibody mF4-31C1 is able to inhibit the outgrowth of pathologic new lymphatic vessels in a mouse model of suture-induced, inflammatory corneal neovascularisation, and whether this antibody specifically inhibits lymphangiogenesis without affecting hemangiogenesis.

METHODS

Three interrupted 11-0 nylon sutures were placed into the corneal stroma of BALB/c mice (6 weeks old) and left in place for 7 days to induce neovascularisation. The treatment group (n = 9) received the anti-VEGFR3 antibody mF4-31C1 intraperitoneally on the day of surgery and 3 days later (0.5 mg/mouse). Control mice received an equal amount of control IgG solution. For immunohistochemistry, corneal flat mounts were stained with LYVE-1 as a specific lymphatic vascular endothelial marker and with CD31 as panendothelial marker. Morphometry was performed with the image analysis software analySIS;B (Soft Imaging Systems GmbH, Münster, Germany). To improve the objectivity and precision of the morphometrical analysis, we established a modified method using grey filter sampling on monochromatic pictures.

RESULTS

The mF4-31C1 antibody-treated mice displayed nearly complete inhibition of lymphangiogenesis compared with IgG controls (p < 0.006). In contrast, there was no significant inhibitory effect observed with respect to blood vessel growth (p > 0.05).

CONCLUSIONS

Inflammatory corneal lymphangiogenesis seems to depend on VEGFR3-signalling. By blocking this receptor the ingrowths of lymphatic vessels can be inhibited almost completely, and specifically without affecting hemangiogenesis. This may open new treatment options to promote (corneal) graft survival without affecting hemangiogenesis.

Bevacizumab as a potent inhibitor of inflammatory corneal angiogenesis and lymphangiogenesis

PURPOSE

To analyze whether bevacizumab can inhibit inflammatory angiogenesis and lymphangiogenesis in the cornea. Bevacizumab (Avastin; Roche, Welwyn Garden City, UK) is a recombinant, humanized, monoclonal antibody against VEGF-A that has been approved by the U.S. Food and Drug Administration for the treatment of colon carcinomas.

METHODS

The mouse model of suture-induced corneal neovascularization was used to assess the antihemangiogenic and antilymphangiogenic effect of bevacizumab by systemic and topical application. Corneal flatmounts were stained with LYVE-1 as a specific lymphatic vascular endothelial marker and CD31 as a pan-endothelial marker, and blood and lymph vascularized areas were analyzed morphometrically. The inhibitory effect of bevacizumab on lymphatic endothelial cells (LECs) was analyzed with a colorimetric (BrdU) proliferation ELISA. The binding ability of bevacizumab to murine VEGF-A was analyzed by Western blot, ELISA, and surface plasmon resonance.

RESULTS

The systemic and topical applications of bevacizumab significantly inhibited the outgrowth of blood (P < 0.006 and P < 0.0001, respectively) and lymphatic (P < 0.002 and P < 0.0001, respectively) vessels. Inhibition of the proliferation of LECs was also significant (P < 0.0001). Western blot analysis, ELISA, and the surface plasmon resonance assay showed that bevacizumab binds murine VEGF-A.

CONCLUSIONS

Topical or systemic application of bevacizumab inhibits both inflammation-induced angiogenesis and lymphangiogenesis in the cornea. This finding suggests an important role of VEGF-A in corneal lymphangiogenesis. Bevacizumab may be useful in preventing immune rejections after penetrating keratoplasty or tumor metastasis via lymphatic vessels.

A special reactor design for investigations of mixing time effects in a scaled-down industrial L-lysine fed-batch fermentation process

A specially designed model reactor based on a 42-L laboratory fermentor was equipped with six stirrers (Rushton turbines) and five cylindrical disks. In this model reactor, the mixing time, Theta(90), turned out to be 13 times longer compared with the 42-L standard laboratory fermentor fitted with two Rushton turbines and four wall-fixed longitudinal baffles. To prove the suitability of the model reactor for scaledown studies of mixing-time-dependent processes, parallel exponential fed-batch cultivations were carried out with the leucine-auxotrophic strain, Corynebacterium glutamicum DSM 5715, serving as a microbial test system. L&HYPHEN;Leucine, the process-limiting substrate, was fed onto the liquid surface of both reactors. Cultivations were conducted using the same inoculum material and equal oxygen supply. The model reactor showed reduced sugar consumption (-14%), reduced ammonium consumption (-19%), and reduced biomass formation (-7%), which resulted in a decrease in L-lysine formation (-12%). These findings were reflected in less specific enzyme activity, which was determined for citrate synthase (CS), phosphoenolpyruvate carboxylase (PEP-C), and aspartate kinase (AK). The reduced specific activity of CS correlated with lower CO(2) evolution (-36%) during cultivation. The model reactor represents a valuable tool to simulate the conditions of poor mixing and inhomogeneous substrate distribution in bioreactors of industrial scale. Copyright 1999 John Wiley & Sons, Inc.

Determination of trehalose by flow injection analysis using immobilized trehalase

A new method for the determination of trehalose by flow injection analysis (FIA) is described. The basic principle is the hydrolysis of the disaccharide trehalose into its monomer d-glucose by trehalase, a periplasmic enzyme of Escherichia coli. d-glucose is quantified spectrophotometrically after reaction with hexokinase and glucose-6-phosphate dehydrogenase. Trehalase is prepared by osmotic shock from a recombinant E. coli strain and precipitated with ammonium sulfate. The enzyme is immobilized on VA-Epoxy Biosynth from Riedel-de-Haën. The immobilization rate is about 60%. The FIA signals show a nonlinear dependence on the trehalose concentration. The resulting curve corresponds to a second-order polynomial that serves as a calibration function for test samples. Immobilized trehalase was used during a period of 4 months without any loss of suitability. Several samples of fermentation broth were tested. The results are verified by HPLC. Within an interval of 2 to 10 g/L trehalose the recovery is about 100-120% with a precision of 7% (coefficient of variation).

7-alkylidenecephalosporin esters as inhibitors of human leukocyte elastase

A series of 7-alkylidenecephalosporins and 7-vinylidenecephalosporins, as their benzhydryl esters, have been tested as inhibitors of both porcine pancreatic elastase and human leukocyte elastase. Selected 7-alkylidenecephalosporin esters are found to be potent inhibitors of HLE. One category of new inhibitors is the 7-(haloalkylidene)cephalosporins. In contrast to previously reported cephalosporin-based elastase inhibitors, these haloalkylidene cephems show optimum inhibitory activity as sulfides, rather than as sulfones. They are efficient and irreversible inhibitors. A second class of active compounds is represented by the benzhydryl ester 7-(cyanomethylidene)cephalosporin sulfone. In contrast to the activity of these new inhibitors, the benzhydryl ester of the mechanism-based beta-lactamase inhibitor, 7-[(2'-pyridyl)methylidene]-cephalosporin sulfone showed little inhibitory activity as an elastase inhibitor. 7-Vinylidenecephalosporins were also relatively poor inhibitors, although the terminally unsubstituted allene sulfide showed activity as an inhibitor of PPE. A modeling analysis suggests the 7-alkylidene substituents can be readily accommodated in the S1 pocket. A potential mechanism of inhibition is proposed.

Virus inactivation of blood products by phenothiazine dyes and light

Methylene blue (MB) and its derivatives azure A, B, C and thionine are photoactive and, in principle, are suitable for photodynamic virus inactivation of blood and blood products, such as therapeutic plasma. Methylene blue was selected for plasma decontamination because it is being clinically used and because of its known toxicological and other properties. The standard procedure for photodynamic treatment of single units of fresh plasma involves illumination with visible light at an MB concentration of 1 microM. Polymerase chain reaction analysis revealed that, in addition to model viruses, the bloodborne viruses hepatitis B virus, hepatitis C virus, human immune deficiency virus-1 and probably also the nonenveloped parvovirus B19 are sensitive to MB/light treatment. The procedure is further improved when the fluorescent tubes routinely used for illumination are replaced by more intense light sources, e.g. light-emitting diodes or low-pressure sodium lamps. Surprisingly, the improved virus kill is accompanied by reduced damage to plasma proteins.

Bupivacaine plasma concentrations during continuous epidural anesthesia in infants and children

Venous bupivacaine plasma concentrations were measured in six neonates and infants aged 4 days to 3.9 mo (mean, 2.1 mo) and 10 infants and children aged 9 mo to 6 yr (mean, 3.1 yr) after administration of an initial bolus of 0.5 mL/kg bupivacaine 0.25%, followed by a continuous infusion of local anesthetic (0.25 mL.kg-1.h-1) over a period of 4 h (first hour: bupivacaine 0.25%, then reduced to 0.125%). Plasma concentrations of local anesthetic measured at 180 min and 300 min after beginning of bupivacaine administration were significantly higher in younger infants when compared to older infants and children (180 min: 0.67 +/- 0.24 micrograms/mL [0.25-0.97] vs 0.27 +/- 0.11 micrograms/mL [0.19-0.55], P < 0.01; 300 min: 0.86 +/- 0.36 micrograms/mL [0.35-1.25] vs 0.34 +/- 0.12 micrograms/mL [0.18-0.57], P < 0.01). The results of our study show that despite applying the same dosage of epidural bupivacaine significantly higher plasma concentrations were seen after short periods of continuous infusion in infants up to 4 mo than in children older than 9 mo.

Target structures for HIV-1 inactivation by methylene blue and light

In a photodynamic virus inactivation procedure for human fresh frozen plasma the plasma is exposed to visible light in the presence of 1 microM methylene blue. This procedure is known to inactivate HIV-1 by at least 10(6.32) TCID50/ml within 10 minutes. To elucidate the mechanism of photodynamic inactivation of HIV-1 by methylene blue/light treatment, reverse transcriptase (RT), the HIV-1 associated protein p24, and viral RNA were examined. In the dark, methylene blue up to 10 microM has no inhibitory effect on recombinant RT. In the presence of light, recombinant RT inactivation was dependent on illumination time and the concentration of methylene blue. After photoinactivation of the whole virus by methylene blue/light treatment, RT activity was also almost completely inhibited. Simultaneously, it was found by Western blotting that HIV-1 p24 and gp120 are altered in size, possibly due to protein cross-linking. In addition, it was shown by polymerase chain reaction (PCR) inhibition assay that HIV-1 inactivation leads to destruction of its RNA. In summary, methylene blue/light treatment acts on HIV-1 at different target sites: the envelope and core proteins, and the inner core structures RNA and RT.

The effects of epidural and intravenous lidocaine on somatosensory evoked potentials after stimulation of the posterior tibial nerve

The measurement of somatosensory evoked potentials (SEPs) after stimulation of the posterior tibial nerve (PTN-SEPs) has been proposed as an objective indicator of the quality of lumbar epidural block. It is unclear whether peak latency increases after epidural application of local anesthetics may be due in part to systemic effects of the drug absorbed from the epidural space. In this clinical study, we compared PTN-SEPs after intravenous and epidural administration of lidocaine to those of a control group who did not receive lidocaine. Plasma concentrations of lidocaine remained within expected ranges for epidural and intravenous administration. No subjects developed signs for overdose or toxicity. After epidural application of 2% lidocaine, mean latencies of peaks P1, N1, and P2 increased significantly in comparison to baseline values. In 3 of 10 patients, latency changes were not observed. Intravenous lidocaine did not produce statistically significant changes in latencies, although a trend toward increasing latencies appeared to be present. In the control group without lidocaine, no statistically significant changes occurred during the 1-h study period. No correlation was found between peak latency changes and plasma concentrations of lidocaine. We conclude that latency increases observed after epidural application of lidocaine are due primarily to local, not systemic, effects of the local anesthetic.

Synthesis and biological activity of 7-alkylidenecephems

Several 7-alkylidenecephalosporins were synthesized and biologically evaluated as beta-lactamase inhibitors. The three beta-lactamase enzymes used in this study included two type C beta-lactamases, derived from Enterobacter cloacae P99 and E. cloacae SC12368, and one type A beta-lactamase, derived from Escherichia coli WC3310. Of the cephalosporins prepared, compound 7e, the sodium salt of 7-[(Z)-(2'-pyridyl)methylene]cephalosporanic acid sulfone, was found to have excellent inhibitory properties against both type C enzymes. Also, compound 7f, the sodium salt of 7-[(Z)-(tert-butoxycarbonyl)methylene]cephalosporanic acid sulfone showed high activity as an inhibitor of the type A enzyme. The inhibition kinetics of 7e were further explored. The IC50 value of 7e indicated that this compound was approximately 20-fold more active than tazobactam against the enzyme derived from E. cloacae P99 and 167-fold more active than tazobactam against the enzyme derived from E. cloacae SC12368. A plot of enzymatic activity vs incubation time with stoichiometric amounts of inhibitor reveals a rapid deactivation of the enzyme followed by an extremely slow reactivation. 7e exhibited a second-order rate constant of k3' = 5.3 x 10(6) L/mol.min, and a partition ratio of approximately 20:1 inhibitor:enzyme was determined for this inhibitor. After separation of excess inhibitor with Sephadex filtration, a rate constant of enzyme reactivation was measured at kreactiv = 1.0 x 10(-3) s-1. Following 24 h of incubation of enzyme with a large excess of inhibitor and sephadex filtration to remove excess inhibitor, the enzyme was able to recover only 43% of its original activity, indicating an irreversible component to the inhibition. Potential mechanisms of inhibition for both 7e and 7f are suggested.

[A possible risk for geriatric risk patients caused by intraoperative disorder of cerebral energy utilization?]

OBJECTIVE

This study was carried out on cerebrospinal fluid (CSF) to investigate the perioperative course of certain ischaemic markers, namely neurone-specific enolase (NSE), creatine kinase (CK-BB), hypoxanthine, and lactate in order to identify a disturbed cerebral energy utilisation which could be responsible for the development of temporary mental dysfunctions. Those dysfunctions are characterised by preserved memory content and perception, but the coordination and association of these functions are disturbed. Typical clinical signs are motor restlessness, disordered emotions, and symptoms of dementia. Little is known about the aetiology of those symptoms, but they are most likely due to various events, such as direct drug effects, the extent of surgical trauma, sensorial deprivation, and disturbed perfusion.

METHODS

Eight orthopaedic patients (ASA III or IV) scheduled for removal of their total hip replacement were anaesthetised by catheter-spinal anaesthesia (CSA) for pain relief in combination with standardised, modified neuroleptanalgesia (NLA). At six defined times (15 hours preoperatively, immediately before and after surgery and 6, 24, and 36 hours postoperatively) CSF samples were drawn and the ischaemic markers were determined by means of radioimmunoassay (NSE), electrophoresis (CK-BB), photometry (lactate), and high-pressure liquid chromatography (hypoxanthine). The release of ischaemic markers into CSF correlates linear with the extent of ischaemic brain damage.

RESULTS

Mean concentrations of the following ischaemic markers increased in all patients intraoperatively: NSE from 12.3 ng/ml to 13.4 ng/ml, hypoxanthine from 1.86 mumol/l to 3.73 mumol/l, and lactate from 1.4 mmol/l to 2.0 mmol/l respectively, all of which returned to normal within 36 hours. The CK-BB concentrations were all within normal values and not affected by the operation during this investigation.

CONCLUSION

Although no clinical signs of temporary mental dysfunction have been observed, the results indicate that in CSF ischaemic markers temporarily undergo certain changes in their concentrations during the removal of total hip replacements in elderly patients. These changes are reason for assuming that risk patients may suffer a temporary disturbed cerebral energy utilisation intraoperatively, even if stable clinical and cardiovascular conditions prevail under anaesthesia. Such a temporary ischaemic penumbra might be responsible for the postoperative development of temporary mental dysfunctions.

Variability of the env gene in cynomolgus macaques persistently infected with human immunodeficiency virus type 2 strain ben

The sequence variability of distinct regions of the proviral env gene of human immunodeficiency virus type 2 strain ben (HIV-2ben) isolated sequentially over 3 to 4 years from six experimentally infected macaques was studied. The regions investigated were homologous to the V1, V2, V3, V4, V5, and V7 hypervariable regions identified in the env genes of HIV-1 and simian immunodeficiency virus SIVmac, respectively. In contrast to findings with HIV-1 and SIVmac, the V1- and V2-homologous regions were found to be highly conserved during the course of the HIV-2ben infection in macaques. The V3-homologous region showed a degree of variation comparable to that of HIV-1 but not of SIV. In the V4-, V5-, and V7-homologous regions, mutation hot spots were detected in most reisolates of the infected monkeys. Most of these mutations occurred during the first 10 weeks after infection. After 50 weeks, new mutations were rarely detected. At most mutation sites, a dynamic equilibrium between the mutated viral isotype and the infecting predominant wild type was present. This equilibrium might prevent an accumulation of mutations in isolates later in the course of infection.

Effectiveness of coronary heart disease risk management in high-risk patients

The purpose of this study was to investigate the efficacy of the patient-based coronary heart disease (CHD) risk management strategy in general practice by analyzing patients who were sent to a specialized center as refractory to conventional treatment. Of the 452 patients studied, 152 were excluded because of secondary hyperlipidemia. The effects of a food protocol-monitored dietary/drug treatment on lipid profiles and CHD risk indices and the compliance to this approach were monitored for 12 months in 300 of 452 patients. CHD risk classification was performed according to NIH criteria by the referring physicians, but secondary hyperlipidemia was not identified and treated appropriately. Physicians did not fully utilize dietary and drug treatment and referred the patients to a specialized center too early. The initiated food protocol-controlled treatment was more efficient than pretreatment in general practice, with a compliance of 80.3% by patients selected according to their CHD risk. Long-term CHD risk reduction was persistent for 12 months in compliant patients; however, a cumulative dropout rate of 43% after 6 months and of 68% after 12 months was noted. Statistical analysis failed to reveal consistent prognostic factors of long-term compliance.

Identification of crossovers in Wilson disease families as reference points for a genetic localization of the gene

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism. A minimum recombinant analysis using D13S22, ESD, RB1, D13S31, D13S55, D13S26, D13S39, and D13S12, all localized at 13q14-q22, has been carried out in 20 WD families of Northwest-European origin. No inconsistencies have been observed with respect to locus order or location of the WD locus (WND) compared with previous linkage studies. D13S31 was mapped as the closest marker proximal to WND, whereas D13S55 and D13S26 were mapped as the closest markers distal to WND. We have identified a crossover between WND and D13S31 in one family and a crossover between WND and D13S55 in another. These crossover sites can be used as reference points for new chromosome 13q14-q21 markers, and are therefore important for a more accurate mapping of the WD locus.

Genetic and biochemical analysis of the aspartokinase from Corynebacterium glutamicum

The lysC/asd gene cluster of Corynebacterium glutamicum ATCC 13032 was cloned and sequenced. The lysC locus coding for aspartokinase consists of two in-frame overlapping genes, lysC alpha encoding a protein of 421 amino acids (Mr 44,300) and lysC beta encoding a protein of 172 amino acids (Mr 18,600). The C. glutamicum aspartokinase was purified and found to contain two proteins of Mr 47,000 and Mr 18,000. A C. glutamicum mutant expressing a feedback-resistant aspartokinase was shown to be changed in a single base pair of the lysC beta gene, leading to an amino acid exchange in the beta-subunit of the aspartokinase. In addition, the identified mutation was found to be responsible for the enhanced expression of the asd gene located downstream of lysC.

[Fetal methemoglobinemia caused by prilocaine--is use of prilocaine for pudendal block still justified?]

17 women received 2 x 10 ml prilocaine 1% as a pudendal block sub partu. At delivery, the foetomaternal distribution ratio of the local anaesthetic was evaluated and the development of Met-Hb-concentration in the neonate was measured up to six hours post partum. The Met-Hb-concentration in the neonate was relatively low with a maximum of 1.8% after two hours, followed by a steady decline. A probable explanation for the Met-Hb-concentration could be the unexpected low foetomaternal ratio of distribution (0.5) and the increased renal elimination of the amide-type local anaesthetic in the neonate, respectively. According to these results, no contraindication for prilocaine in pudendal block is indicated.

Cloning of a DNA fragment from Corynebacterium glutamicum conferring aminoethyl cysteine resistance and feedback resistance to aspartokinase

The Corynebacterium glutamicum/Escherichia coli shuttle vector plasmid pZ1 was used to clone the S-(2-aminoethyl)-D,L-cysteine (AEC)-resistance gene from a lysine-excreting, AEC-resistant strain of C. glutamicum, the aspartokinase activity of which was released from feedback inhibition by mixtures of lysine and threonine or AEC and threonine respectively. A recombinant plasmid designated pCS2 carrying a 9.9-kb chromosomal insert that conferred AEC resistance and the ability to excrete lysine to its host was isolated. The aspartokinase activity of the pCS2-carrying strain was resistant towards inhibition by mixtures of lysine and threonine or AEC and threonine respectively. By deletion analysis the DNA region conferring AEC resistance to the host and feedback resistance to its aspartokinase activity could be confined to a 1.2-kb DNA fragment.

A novel proviral clone of HIV-2: biological and phylogenetic relationship to other primate immunodeficiency viruses

Infectious molecular clones of the human immunodeficiency virus type 2 (HIV-2) will be valuable tools for the study of regulatory gene functions and the development of an animal model for the human acquired immunodeficiency syndrome (AIDS). To this end, we have cloned and sequenced a novel HIV-2 isolate, HIV-2BEN. One clone, designated MK6, is infectious for various human T-cell lines and for human and macaque peripheral blood lymphocytes (PBL), allowing molecular studies of HIV-2 infection and replication. Since MK6 is highly cytopathic in MT-2 and Molt-4 clone 8 cells, antiviral agents and neutralizing sera may be tested. Cluster analysis of HIV-1, HIV-2, and simian immunodeficiency virus (SIV) env and gag genes revealed that HIV-2BEN yielded the earliest node of phylogenetic divergence for all reported HIV-2 sequences. Noise analysis showed that, with the current data, no specification of any branching order can be made among the four groups of primate lentiviruses, HIV-1, HIV-2/SIVSMM/MAC, SIVAGM, and SIVMND.

Protein binding of prilocaine in human plasma: influence of concentration, pH and temperature

Protein binding of prilocaine was investigated in vitro under various conditions of changing pH, temperature and total plasma concentration by means of HPLC with UV-detection and ultrafiltration. Whereas changes in temperature (25 degrees C-40 degrees C) and pH (pH 5-pH 10) influenced protein binding markedly, rising plasma concentrations up to 16 micrograms/ml did not affect plasma protein binding significantly. This may be a possible explanation for clinical evidence of low toxicity associated with the use of prilocaine. Discussions concerning protein binding of local anaesthetics should always be based on defined ambient conditions (pH, temperature, concentration).

Improvement of PCR amplified DNA sequencing with the aid of detergents

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[Utilization of sulfite leach by yeasts: growth parameters of producer and fusion strains]

The growth characteristics of a Candida strain (T1), a Pichia strain (T2), and of a fusion product of T2-mutants (fp-T2) have been examined in batch and continuous cultures with the single substrates xylose, acetate, glucose, mannose, and galactose or mixed substrates of them. Maximum specific growth rate (mumax), substrate saturation constant (KS), substrate inhibition (KSi), yield (Y), dilution rate (D), and the protein content of the strains have been compared. The significance of the results for the production of single cell protein is pointed out.

[Maternal and neonatal bupivacaine plasma levels in peridural anesthesia for relief of labor pain]

Peripheral venous blood samples were drawn for bupivacaine analyses (gas chromatography) from 24 patients under epidural anaesthesia, used to reduce pain caused by contractions. The specimens were taken 10, 20, 30 and up to 45 minutes following a first injection of 11 to 13 ml bupivacaine 0.25%, before, 15 as well as 30 minutes after each repetitive dose and at childbirth. Immediately after cord clamping, blood sampling in the neonate was performed to evaluate bupivacaine concentrations in the umbilical artery and vein. Additionally, apgar scores and blood gas parameters were checked and compared with those of neonates, born without analgesic treatment of their mothers. Using bupivacaine 0.25% (average 12 ml) for epidural anaesthesia, the peak plasma levels (mean = 0.2 micrograms/ml) were found 10 minutes after application of the analgesic dose. In one patient a maximum bupivacaine plasma concentration (0.47 micrograms/ml) was determined 15 minutes after the second repetitive dose of 5 ml bupivacaine 0.25%. Apgar scores and results of blood gas analyses demonstrated no significant difference between neonates born spontaneously under regional anaesthesia or without any analgesic treatment of their mothers, respectively. Using bupivacaine 0.25% in epidural anaesthesia for pain relief in labour, we found maternal and neonatal plasma concentrations of the local anaesthetic drug far below the accepted threshold level which might produce systemic toxic reactions.

Cloning and nucleotide sequence of the phosphoenolpyruvate carboxylase-coding gene of Corynebacterium glutamicum ATCC13032

As a first step in determining the importance of the anaplerotic function of phosphoenolpyruvate carboxylase (PEPC) in amino acid biosynthesis, the ppc gene coding for PEPC of Corynebacterium glutamicum ATCC13032 has been cloned by complementation of an Escherichia coli ppc mutant strain. PEPC activity encoded by the cloned gene is not affected by acetyl-CoA under conditions where the E. coli enzyme is strongly activated, whereas acetyl-CoA is able to relieve inhibition by L-aspartate used singly or in combination with alpha-ketoglutarate. Amplification of the ppc gene in a C. glutamicum lysine-excreting strain resulted in increased PEPC-specific activity and lysine productivity. The nucleotide sequence of a DNA fragment of 4885 bp encompassing the ppc gene has been determined. At the amino acid level, PEPC from C. glutamicum presents overall a high degree of similarity with corresponding enzymes from three different organisms. The location of some strictly conserved regions may have important implications for PEPC activity and allostery.

[Plasma concentrations of lidocaine and prilocaine following infiltration anesthesia in otorhinolaryngologic surgery]

Infiltration anaesthesia is still relevant for the surgical treatment of patients in otorhinolaryngology. The injection of local anaesthetics in well vascularised areas constantly causes the danger of high plasma concentrations of local anaesthetics combined with undesirable side effects. In our study we tried to determine the development of plasma concentrations of local anaesthetics in patients scheduled for routine tonsillectomies and tympanoplasty.

MATERIALS AND METHODS

In 45 patients the development of plasma concentrations was measured immediately after the injection at short intervals; the samples were obtained between 1 minute and 60 minutes after the first injection. Group 1: Lidocaine 0.5% with epinephrine (1:200,000) 15-20 ml for tonsillectomy (n = 18). Group 2: Lidocaine 0.5% with epinephrine (1:200,000) 8-15 ml for tympanoplasty (n = 15). Group 3: Prilocaine 1% with epinephrine (1:200,000) 8-15 ml for tympanoplasty (n = 15). For tactical reasons infiltration anaesthesia for the patients of group 2 was - in addition to general anaesthesia - applied by the otorhinolaryngologist, whereas the patients of groups 1 and 3 were operated exclusively under local anaesthesia.

RESULTS

Within the first minute after the initial injection plasma concentrations of the local anesthetic increased close to toxic threshold levels that are associated with undesirable systemic side effects. In the patients of group 1, who underwent tonsillectomy, plasma concentrations of 4-7 micrograms/ml were found during the first minute. The highest average values always appeared within the first five minutes: group 1 2.07 micrograms/ml, group 2: 0.45 micrograms/ml, and group 3: 1.15 micrograms/ml.

DISCUSSION

With infiltration anaesthesia in well vascularised areas it may happen that there are--mainly in the early stage--high plasma concentrations of the applied substances, although the total dose was below the known maximum. Despite careful technique (repeated aspiration test in two levels) at least partial intravascular injections are apparently not always avoidable according to the pharmacokinetic data. Our results demonstrate that in addition to a safe peripheral venous line and prophylactic oxygen therapy, intraoperative monitoring of blood pressure, heart rate, electrocardiogram and verbal patient monitoring is of advantage in this group of patients. In our opinion the "standby function" of an anaesthesiologist can avoid severe complications.

[Experiences with parenteral administration of diltiazem in coronary surgery patients]

Diltiazem is a calcium channel blocker whose effects lie between those of the two other important calcium antagonists nifedipine and verapamil. In addition to vasodilation, it has a negative dromotropic effect with prolongation of the A-V interval. In animal experiments and human investigations, diltiazem improves the function of ischemic myocardium due to a direct dilating effect on coronary vessels. The purpose of the present study was to investigate the hemodynamic effects of diltiazem in patients before and during coronary revascularization. METHODS. The study included 60 consenting male patients with coronary heart disease. Twenty premedicated patients randomly received 0.3 mg/kg diltiazem or placebo within 3 min before induction of anesthesia. Hemodynamic measurements (arterial pressure, heart rate, mean pulmonary arterial pressure, pulmonary capillary pressure, right atrial pressure and cardiac output) were taken during the following 21 min. Before cannulation of the great vessels for institution of extracorporeal circulation (ECC), 20 other patients received 0.014 mg diltiazem or placebo/kg per min over 20 min. In addition to the above mentioned hemodynamic measurements, left ventricular parameters (LVP, LVEDP, dp/dt) were directly registered, and 5 min after the end of ECC the measurements were repeated with the same preload as before the ECC. Twenty additional patients received 0.014 mg diltiazem or placebo/kg per min within 21 min during ECC observing arterial perfusion pressure and oxygenator volume. RESULTS. Pre- and intraoperatively diltiazem caused a decrease in mean arterial pressure; cardiac index increased only during the preoperative investigation period (Tables 1, 2), whereas stroke volume index increased pre- and intraoperatively; heart rate decreased in all patients as well as dp/dt (Fig. 1).(ABSTRACT TRUNCATED AT 250 WORDS)

[Sedative-analgesic medication in intensive care patients needing ventilator treatment]

It was the aim of this study to compare two regimens for sedation and analgesia during ventilator treatment in intensive care patients. Special regard was given to endocrine stress response, neuro-monitoring, hemodynamic parameters and clinical practicability.

METHODS

A total number of 16 patients of an operative ICU were randomly allocated to the following groups: (1) Fentanyl-group, approximately 0.2 mg/h fentanyl, 2.5 mg/h midazolam and 2 mg/h pancuronium in intermittent doses, (2) ketamine-group, about 50 mg/h ketamine and 2.5 mg/h midazolam by syringe pump, in addition 2 mg/h pancuronium. During a period of 2 days and in intervalls of 6 h, plasma levels of epinephrine and norepinephrine (by HPLC/ECD), ADH, ACTH and cortisol (by RIA), ketamine (by GC) and stress-metabolites (glucose, lactate, free glycerol) were determined. Hemodynamic parameters were investigated in intervalls of 12 h, EEG (Compressed Spectral Array, CSA) in intervalls of 24 h. In addition, routine laboratory data, vigilance and adaptation to the respirator were observed.

RESULTS

Plasma levels of adrenaline, noradrenaline, dopamine, ADH, ACTH, cortisol and stress-metabolites were comparable in both groups. Levels of ADH, ACTH, cortisol and free glycerol did not leave the normal range. In three patients, in which epinephrine- or norepinephrine-infusions were necessary to improve cardiocirculatory stability, this treatment could be finished after beginning of the ketamine application. In both groups, CSA showed a dominant delta- und theta-activity according to the clinical aspects of sufficient sedation and analgesia. Hemodynamic parameters were comparable in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hemodynamic action profile of propofol in comparison with midazolam. A study in coronary surgical patients]

Propofol, a rapid and short-acting i.v. anesthetic, was associated with the risk of anaphylactic reactions in its original cremophor-EL formulation. It has been reformulated in a soybean emulsion with satisfactory anesthetic properties. A former study of hemodynamic changes after i.v. induction with propofol, thiopental, methohexital, etomidate, and midazolam in patients with coronary artery disease demonstrated that in comparison to other induction agents propofol depressed systolic and diastolic arterial pressures more severely, compromising coronary perfusion. In the present investigation left ventricular parameters as well as hemodynamic effects during extracorporeal circulation (ECC) were studied in comparison to midazolam during opiate analgesia. Methods. Hemodynamic effects of 2 mg/kg body weight propofol as compared to 0.15 mg/kg midazolam were studied in 34 patients during coronary artery surgery before cannulation of the large vessels (measurement of left ventricular parameters) or during ECC (measurement of arterial perfusion pressure and oxygenator volume). Results (see Table 1, Figs. 1 and 2). Propofol decreased systolic and diastolic pressures (-27%, -22%) more than midazolam (-10%, -9%). Cardiac index and stroke volume index were diminished following both drugs (propofol: -14%, -9%; midazolam: -15%, -11%); total systemic resistance was reduced significantly by propofol (-22%). Dp/dtmax was compromised more markedly by propofol (-24%) than by midazolam (-18%), but there was no significant difference.(ABSTRACT TRUNCATED AT 250 WORDS)

[The endocrine stress-reaction to orotracheal intubation and topical anesthesia with lidocaine]

The influence of laryngoscopy and intubation with or without topical lidocaine anesthesia on the endocrine stress response was investigated in six groups of 40 orthopedic surgery patients differing in premedication and technique of lidocaine application (one- or two-step method). Controls were included without lidocaine application. Plasma levels of catecholamines (by HPLC) were measured before induction and 1, 5, and 10 min after intubation, ADH-levels (by RIA) before induction and 5 and 10 min after intubation. In addition, mean arterial pressure (MAP, MAP), HR, and the incidence of coughing and cardiac arrhythmias were observed. The statistical evaluation (analysis of variance with repeated measures on one factor) considered P values of less than 0.05 significant. There was no influence of laryngoscopy and intubation on plasma catecholamine levels during the observation period. A continuous decrease in both levels of epinephrine and norepinephrine was significant. ADH levels showed no significant changes. Lidocaine had no influence on these endocrine parameters. MAP and HR increased after intubation in all groups studied. The increase in HR was less pronounced after lidocaine treatment. Coughing (4 patients) and ventricular dysrhythmia (2 patients) were observed only in patients without lidocaine treatment. In conclusion, no influence of different modes of treatment on the endocrine stress response during intubation became obvious. There was no indication that the cardiovascular symptoms during laryngoscopy and intubation are caused by systemic stress. An explanation may be a direct neural impulse via sympathetic efferents to the heart. On the other hand, topical application of lidocaine did prevent coughing and cardiac irritation, and the increase in HR was attenuated.(ABSTRACT TRUNCATED AT 250 WORDS)

[Incidence of air embolism in implantation of hip prostheses]

The prosthetic supply of the hip-joint may be accompanied by the problem of venous air embolism. By including 53 orthopaedic patients having undergone total hip replacement, the influence of bone-cement as well as of the different anaesthetic techniques on the frequency of embolic phenomenons was investigated. Embolism was determined as an abrupt decrease (greater than 5 mmHg) in the end-tidal pCO2. Venous embolism often occurred with cemented endoprostheses in contrast to non-cement implantations. Patients with general anaesthesia presented more often with venous air embolism than patients with epidural anaesthesia. This might be explained by an expanding effect of nitrous oxide on air bubbles entering the vascular bed under the implantation of the shaft-prostheses. Our data stress the importance of continuous monitoring of end-tidal pCO2 for early discovery of lung embolism.

Deoxyribonucleotide biosynthesis in green algae: characterization of thymidylate synthase-dihydrofolate reductase in Scenedesmus obliquus

Thymidylate synthase and dihydrofolate reductase are peak enzymes that accompany the S phase of the unicellular green algae, Scenedesmus obliquus, and are both overproduced in the presence of 5-fluorodeoxyuridine. Such overproducing cultures have served for enzyme isolation and characterization. It has not been possible to separate the two enzyme activities by several methods of protein fractionation, including affinity chromatography on specific immobilized ligands (fluorodeoxyuridylate or N10-formylfolate); both were enriched in parallel approximately 400-fold from algal extracts. The most highly purified samples are of low stability in solution. Enzyme activities are inhibited by methotrexate, 5-fluorodeoxyuridylate, and arabinouridylate but not by hydroxyurea; FdUMP inhibition is fully reversed after removal of the nucleotide. Sedimentation in sucrose gradients (Mr 100,000) and electrophoresis in denaturing polyacrylamide gels (Mr 50,000) suggest that the protein structure resembles more the dimeric, bifunctional thymidylate synthase-dihydrofolate reductase of protozoan species than the separate enzymes found in bacteria and animal cells.

[Metabolic changes caused by an extremities tourniquet and its modification by anesthesia procedures]

In 3 groups of 15 patients, respectively, we studied metabolic changes following tourniquet-release after operations of lower extremity. The influence of different anesthetic methods was evaluated by blood-gas-analyses up to 30 minutes after blood-circulation of the lower limb had been reinstalled. Our results demonstrate, that the patients under regional anesthesia with spontaneous respiration (group 1) could preserve their metabolic equilibrium with minor changes within the physiologic range. The intubated patients with controlled respiration (group 2) revealed a marked metabolic acidosis after tourniquet-release with insufficient respiratory compensation. Initial values were not reached within 30 minutes. The patients of group 3 (controlled respiration with a 25% increase of the normal minute volume for a period of 5 minutes after release of the tourniquet) had a less severe acidosis than those of group 2. The beneficial influence of spontaneous respiration in compensating metabolic acidosis--even in aged patients--following an ischemic tourniquet has been demonstrated by this investigation. Short-term hyperventilation seems to be the therapeutic tool in patients with controlled respiration to compensate for metabolic acidosis up to a certain extent.

[Anesthesia procedures and perioperative patient monitoring in chemonucleolysis]

Premedication with H1 and H2 blockers as well as cortisone to reduce or prevent allergic reactions should be an integral part of the overall treatment. The facilities for immediate treatment of anaphylactic reactions including cardiopulmonary resuscitation must be readily available. Our haemodynamic measurements allow us to give a negative answer to the question--so far not investigated in man--whether the use of chymopapain or of its fragments leads to constant cardiocirculatory effective reactions in the early phase. Our experiences collected so far favour catheter peridural anaesthesia as the method of choice in chemonucleolyses.