Rapid electrochemiluminescence assays of polymerase chain reaction products

We demonstrate the first use of an electrochemiluminescent (ECL) label, [4-(N-succimidyloxycarbonylpropyl)-4'-methyl-2,2'- bipyridine]ruthenium(II) dihexafluorophosphate (Origen label; IGEN Inc.), in DNA probe assays. This label allows rapid (less than 25 min) quantification and detection of polymerase chain reaction (PCR)-amplified products from oncogenes, viruses, and cloned genes. For the PCR, we used labeled oligonucleotide primers complementary to human papiloma virus and the Ha-ras oncogene. These samples were followed by ECL analysis or hybridization with specific, Origen-labeled oligonucleotide probes. These studies demonstrate the speed, specificity, and effectiveness of the new ECL labels, compared with 32P, for nucleic acid probe applications. We describe formats involving conventional methodologies and a new format that requires no wash step, allowing simple and rapid sample analysis. These rapid assays also reduce PCR contamination, by requiring less sample handling. Improvements in ECL detectability are currently under investigation for use in DNA probe assays without amplification.

Electrochemiluminescence detection for development of immunoassays and DNA probe assays for clinical diagnostics

Electrochemiluminescence (ECL) has been developed as a highly sensitive process in which reactive species are generated from stable precursors (i.e., the ECL-active label) at the surface of an electrode. This new technology has many distinct advantages over other detection systems: no radioisotopes are used; detection limits for label are extremely low (200 fmol/L); the dynamic range for label quantification extends over six orders of magnitude; the labels are extremely stable compared with those of most other chemiluminescent systems; the labels, small molecules (approximately 1000 Da), can be used to label haptens or large molecules, and multiple labels can be coupled to proteins or oligonucleotides without affecting immunoreactivity, solubility, or ability to hybridize; because the chemiluminescence is initiated electrochemically, selectivity of bound and unbound fractions can be based on the ability of labeled species to access the electrode surface, so that both separation and nonseparation assays can be set up; and measurement is simple and rapid, requiring only a few seconds. We illustrate ECL in nonseparation immunoassays for digoxin and thyrotropin and in separation immunoassays for carcinoembryonic antigen and alpha-fetoprotein. The application of ECL for detection of polymerase chain reaction products is described and exemplified by quantifying the HIV1 gag gene.

Intrahospital transport of critically ill patients

Severe complications sometimes occur in critically ill patients during intrahospital transport. Possible causes may be inadequate ventilation, insufficient monitoring, interrupted application of vasoactive drugs, or disconnections and accidental extubation. We constructed a transport unit equipped with a respirator; capnometer; monitor to measure ECG, arterial and intracranial pressures, and temperature; and two syringe pumps that can be connected easily to the patient's bed. Gas is supplied by cylinders with oxygen and air. Electrical power is supplied by two accumulators connected to recharger and transformer devices that deliver 220 V (110 V). Since this transfer unit was introduced, we have had no unanticipated problems during intrahospital ICU patient transport.

Clearance of ceftriaxone in critical care patients with acute renal failure

Serum concentrations of ceftriaxone (RocephinTM), a third generation cephalosporin, were monitored in 5 operative intensive care patients suffering from acute renal failure (ARF) and compared to those of 7 patients without renal disturbance. For a period of 7 days, a fixed dose of 2 g/day was given by a 15 min infusion. Pharmacokinetic parameters were calculated by fitting all serum and urine data measured over the period of treatment. Ceftriaxone free fraction was measured on days 2 and 7. There was no evidence for an intraindividual change in ceftriaxone-clearance during the observation period. Ceftriaxone renal clearance was closely dependent on creatinine clearance according to a linear regression expressed by Clren = 0.14 Clcrea + 2.2 (r = 0.951, p less than 0.0001). Total clearance was also associated with creatinine clearance: Cltot = 0.19 Clcrea + 8.2 (r = 0.964, p less than 0.0001). Related to the free fraction, renal clearance was in the range of the glomerular filtration rate. Non-renal clearance was strongly decreased when related to the free fraction indicating that biliary excretion is also impaired in patients with acute renal failure. Obviously no compensatory increase in hepatic ceftriaxone clearance takes place. It is concluded that elimination of ceftriaxone may be strongly impaired during acute renal failure in surgical intensive care patients and that dosage should be restricted according to degree of the impairment of creatinine clearance.

Utilization of labeled thymidine in DNA synthesis: studies for PET

Carbon-111-thymidine and positron emission tomography (PET) have the potential for noninvasively measuring DNA synthesis in tumors and tissues. In order to validate this potential, one needs to construct accurate biochemical models that reflect the metabolism of thymidine, including its uptake and degradation as well as its incorporation into DNA. Our studies employed thymidine labeled in the methyl position using 11C, 14C, and 3H. Studies with rapidly proliferating tissues of mice demonstrated that most of the activity, 60 min after injection of labeled thymidine, was present in DNA, with smaller amounts found in metabolites. Studies in dogs, however, reveal that more activity was present in metabolites, rather than in the DNA of tumors and spleen tissue. HPLC analysis of canine blood after the injection of thymidine revealed rapid conversion of thymidine to thymine and other metabolites. We have found significant differences in the metabolism of [3H]thymidine versus thymidine labeled with radioactive carbon. These differences, which were not found when comparing 14C and 11C, indicate that [3H]thymidine is not an appropriate standard for comparison with PET studies employing [11C] thymidine. To accurately interpret images of [11C]thymidine as representations of DNA synthesis we are developing kinetic models that take into account the metabolism of thymidine and the contribution of degradation products to the 11C images.

Ehrlichiosis in a dog with seizures and nonregenerative anemia

Ehrlichia canis infection was diagnosed in a dog with a history of seizures and nonregenerative anemia. Serologic titer to E canis was greater than 1:100. Evaluation of CSF revealed a high cell count, high protein concentration, and a positive Pandy test result. Several mononuclear leukocytes in the CSF contained E canis morulae. Central nervous system lesions are commonly found on postmortem examination of animals with ehrlichiosis, although clinical reports of neurologic signs attributable to this disease are less common. Ehrlichiosis should be included in the differential diagnosis of CNS disease in dogs from enzootic areas.

[Faulty functioning of the expiration valve of the Dräger circle system]

We observed, that under controlled ventilation the expiration valve of the circle system "8 ISO" did not close and rebreathing occurred, as the spirometer run counterclockwise. In such potentially dangerous events only a capnometer which measures inspiratory CO2 would give alarm. Dräger is informed of the above and until the problem is resolved, every anaesthesist should watch the expiration valve and spirometer carefully.

[Is cerebral panangiography unnecessary in determining brain death?]

The diagnosis of brain death, i.e. death of cortex and brainstem, can be established by neurologic examination only if there is no intoxication, sedative therapy, or hypothermia. In the latter cases, until now only cerebral panangiography can establish the diagnosis. We investigated, whether in these cases cerebral perfusion scintigraphy (CPS) in combination with brainstem auditory evoked potential (BAEP) can replace CPA for establishing the diagnosis.

METHODS

40 patients, treated in our interdisciplinary ICU because of primary or secondary brain lesions and in whom determination of brain death by neurological examination was contraindicated, were subjected to the following procedure: When coma was diagnosed, brainstem reflexes were examined. If negative, an atropine-test was done and this being negative, apnea-testing was performed. If apnea was positive, BAEP, CPS and CPA were performed. The results of BAEP and CPS were compared with the results of CPA.

RESULTS

In 38 patients with suspected brain death the first examination showed complete correspondence between BAEP and CPS on one hand and CPA on the other hand (Table 3). In patient No. 39, CPS as well as CPA showed minimal supratentorial circulation, whereas BAEP were negative as was circulation in the fossa posterior. In patient No. 40 as well CPS and CPA showed minimal supratentorial circulation. Brainstem testing with BAEP was negative although CPA showed minimal brainstem perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

[Incorrect placement of a vena cava catheter and its prevention by intra-atrial ECG]

Up to now, radiological position control was obligatory due to the frequent complications arising from false cava catheter positioning. Apart from the radiological control, which is time consuming and expensive and involves the danger of allergic reactions due to contrast media, intraatrial ECG-recording can be applied to achieve correct positioning of the catheter tip. By this method exact placement of the catheter tip in the superior vena cava was possible in 98 of 100 cases examined. Only 2 catheters could not be placed: one was placed intra-arterially, and the other could not pass a venous valve. The method proved to be inexpensive, time saving and could even be applied in emergency situations (intraoperatively). Important prerequisites for the success of the procedure are a disturbance-free ECG-derivation, a sinus rhythm, and sufficient practical experience on the part of the examiner with regard to the assessment of intra-atrial ECG-alterations.

Stable expression of recombinant factor VIII molecules using a bovine papillomavirus vector

The bleeding disorder in hemophilia A results from a deficiency or abnormality of Factor VIII (FVIII), a member of the coagulation cascade. FVIII is a large glycoprotein (approximately 350,000 daltons) that is activated by a series of proteolytic cleavages. During activation, a large internal domain (B domain) is removed, resulting in an active complex comprised of the amino and carboxyl subunits of the parental molecule. Using a bovine papillomavirus expression vector system, we have established stable, genetically engineered cell lines harboring either full-length FVIII cDNA or variant FVIII cDNA (delta FVIII), the latter containing an extensive deletion in the region encoding the B domain. We demonstrate that the two recombinant FVIII molecules manifest the biological attributes of native FVIII. Relative to full-length FVIII transformants, cells harboring delta FVIII cDNA are five to eight times more efficient in expressing coagulant activity. This difference is due to a post-transcriptional event.

Changes in intracranial pressure associated with extradural anaesthesia

The intracranial pressure (ICP) response to the lumbar extradural injection of bupivacaine hydrochloride was measured in two patients on a total of 29 occasions. In the first patient, mean ICP increased from an average figure of 18.8 mm Hg to 39.5 mm Hg after the injection of 10 ml of solution. This increase was maintained for an average of 4.5 min. Both the magnitude and the duration of the increase were less when 5 ml was injected. The second patient had a normal baseline ICP, but the injection of bupivacaine 10 ml produced an increase from a mean of 9.3 mm Hg to 15.6 mm Hg. Injection of the same volumes of physiological saline in the second patient induced increases in ICP similar to those obtained with bupivacaine. There was a good correlation between baseline ICP and the increase produced by the extradural injection. It is concluded that extradural anaesthesia must be used with extreme caution in patients with reduced intracranial compliance, and should not be used at all in a patient with intracranial hypertension or a space-occupying lesion.

Self-monitoring of blood glucose: how accurate are children with diabetes at reading chemstrip bG?

Accuracy of self-monitoring of blood glucose (SMBG) using Chemstrip bG (Bio-Dynamics, Indianapolis, Indiana) was studied in 90 randomly selected children with insulin-dependent diabetes mellitus (IDDM). For 28 children (mean age 8.3 +/- 3.6 yr) a parent routinely read the Chemstrip at home. The remaining 62 children (mean age 13.7 +/- 2.8 yr) read the Chemstrip themselves. Each child or parent analyzed 20 capillary blood samples using Chemstrips and answered a questionnaire on SMBG. The accuracy of SMBG of the group was high (mean correlation coefficient = 0.89 +/- 0.05), but consistency of measurement was variable (mean standard deviation = 1.90 +/- 0.57) and there was a general tendency to underread Chemstrips (mean y-intercept = 1.05 +/- 1.48; mean slope = 0.80 +/- 0.17). For each subject, 0-65% (mean of 34%) of readings were within 10% of the laboratory measurement, and 17-100% (mean 68%) within 20%. These results indicate that most subjects were fairly accurate in reading Chemstrips; however, analysis of accuracy is useful in identifying individuals who are inaccurate or inconsistent in SMBG. Continuing supervision of SMBG is necessary in children with IDDM.

The structure of 2-methoxy-5-(2',3',4'-trimethoxyphenyl)tropone, an effective analog of colchicine

-Methoxy-5-(2',3',4'-trimethoxyphenyl) tropone is an active analog of colchicine, a mitotic spindle inhibitor, which is missing the middle "B" ring. This compound crystallizes in the triclinic system, space group P1, with Z = 2; a = 10.135(2), b = 10.166 (4), and c = 7.863(2) A; alpha = 82.15(3), beta = 103.49(3), and gamma = 107.16(2); degrees and V = 750.7(4) A. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.063, using 2503 observed reflections and 271 parameters. Despite the absence of the middle ring, the conformation of the molecule is similar to that of colchicine, isocolchicine , and their derivatives. The troponoid ring is dissimilar to the phenyl ring in that it is not aromatic and does have alternating short and long bond lengths. The dihedral angle between the least-squares planes of the two rings is -57.4 degrees. Van der Waals surface representations of the analog and colchicine are presented to demonstrate the similarity and differences of these two molecules . The structural information of the analog is consistent with the interpretation of thermodynamic parameters which govern the interactions between brain tubulin and the analog.

[Buprenorphine and pentazocine for postoperative analgesia. A double blind study following abdominal surgery]

A randomized double-blind study was done to test the two opiates buprenorphine (0.3 mg i.v.) and pentazocine (30 mg i.v.) with regard to their applicability for the postoperative phase. These substances were chosen because they are not subject to drug prescription regulations. 60 patients who had undergone epigastric and hypogastric interventions under thiopental-sodium-induced halothane anesthesia received i.v. injections of one of the two analgetics as soon as they requested a pain-killer postoperatively. The subjective pain intensity registered by means of a visual analogue scale shows a gradual decrease after buprenorphine with maximal effects 1-3 h post injectionem (7.3 leads to 1.5). The duration of action is 8.2 +/- 0.7 h on the average (median 8 h; range 4-22 h). The maximal analgetic effect of pentazocine is already attained after 10 min (6.3 leads to 3.2). Thereafter the pain-intensity curve rises again. Pentazocine has a mean duration of action of 2.35 +/- 0.24 h (median 2 h; range 0.5-5 h). The inadequate analgetic effect of pentazocine manifests itself in an only slight initial reduction of the respiratory rate (19.5 leads to 17.5 min-1), which, on the other hand, decreases significantly and continuously under buprenorphine (20.8 leads to 13.5 min-1). Both substances cause increases of PaCO2 (buprenorphine 37.3 leads to 46.8 mmHg; pentazocine 36.3 leads to 43.0 mmHg), values greater than 50 mmHg being attained in individual cases.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of therapeutic hyperventilation on blood lactate concentration]

The increase of blood lactate is a well known side effect of active and passive hyperventilation. In 22 patients who underwent controlled respiration after head injury or elective neurosurgical operations, we measured lactate, pyruvate, pH, and bicarbonate in central venous blood and investigated their interference by hypocapnia. The level of ventilation was between pCO2 equal 25 mmHg and pCO2 equal 45 mmHg, measured in the central venous blood. With decreasing pCO2, pH showed an increasing (from 7.40 +/- 0.015 to 7.50 +/- 0.068) and bicarbonate a decreasing tendency (from 25.46 +/- 1.32 mMol/l to 23.28 +/- 3.76 mMol/l). Lactate and pyruvate remained within the normal range down to a central venous pCO2 of 31 mmHg. But then with increasing hypocapnia both increased significantly (lactate 2.001 +/- 1.08 mMol/l, 0.098 +/- 0.068 mMol/l). At a pCO2-range of 25-27 mmHg (central venous) lactate continued increasing to 2.212 +/- 0.995 mMol/l whereas pyruvate dropped to 0.087 +/- 0.05 mMol/l. Therefore the possibility of hypocapnia-induced lacticemia seems to arise at a ventilation level less than 30 mmHg (pCO2 central venous). Production of excess-lactate may begin at a central venous pCO2 of 27 mmHg.

Changes in plasma renin activity and haemodynamics during vasodilator therapy in conscious dogs with myocardial infarction or chronic volume overload

The aim of the study was to compare the changes in plasma renin activity induced by a vasodilator in normal dogs and in dogs with an impaired cardiac reserve. In normal conscious dogs, a 60-min nitroprusside infusion increased plasma renin activity from 1.05 +/- 0.26 to 8.35 +/- 1.20 ng, angiotensin I ml-1 h-1 (P less than 0.002) and heart rate from 83 +/- 6 to 149 +/- 15 beats/min (P less than 0.002). In five dogs in which a aortocaval fistula had been created 4 weeks earlier, the same infusion still increased plasma renin activity but significantly less than in normal dogs (0.90 +/- 0.29 to 4.44 +/- 0.64 ng ml-1 h-1; P less than 0.01) and the heart rate was unchanged (134 +/- 4 to 139 +/- 7 beats/min; NS). Similarly, in five dogs with a previous myocardial infarction, the heart rats response to nitroprusside was blunted (108 to 107 beats/min;NS) and plasma renin activity increased less than in normal dogs. Plasma renin activity also increased acutely after hydralazine administration in dogs which myocardial infarction (1.05 +/- 0.26 to 8.99 +/- 0.79 ng ml-1 h-1; P less than 0.05); after 1 week of hydralazine, plasma volume had increased from 54.9 +/- 0.9 ml kg-1 to 74.5 +/- 4.9 ml kg-1 (P less than 0.05) and plasma renin activity remained higher than control (4.66 +/- 0.66 ng ml-1 h-1; P less than 0.01). In conclusion, vasodilator therapy rapidly activates vasoconstrictor forces and fluid retention even in dogs with limited cardiac reserve. Although the regulation of plasma renin secretion appears altered in these models of heart disease, the renin response remains sufficient to seriously limit the beneficial effects of vasodilator therapy.

Binding of nickel (II) to 5'-nucleoside monophosphates and related compounds

The interactions of Ni(II) cation with a representative suite of purine bases and the respective nucleosides and nucleotides have been studied by ultraviolet difference spectroscopy. Apparent association constants, Kapp, were determined for each system at pH 7.0, using computer linear regression coupled with an iteration technique. The specificity of binding of Ni2+ for the purine nucleotides studied at pH 7.0 was 5'-GMP greater than 5'-IMP greater than 5'-AMP; a similar ordering was also found for the respective nucleosides and bases. In this study binding was not observed for the suite of pyramidines used, although a Ni2+ - cytidine complex has been observed (Fiskin and Beer, 1965). It was also found that Ni2+ bound more strongly to the purine 5'-nucleotides than to the respective nucleosides and bases. These trends are explained in terms of metal-ligand bonds and available bonding positions on the ligands. A role for metal-ion-nucleotide types of complexes is suggested in the processes that might have given rise to the origin of life.

Changes in control of renin release in congestive heart failure in dogs: response to acute and chronic vasodilator therapy

Neural control of renin secretion is an important physiologic mechanism, but alterations in the central nervous system feedback and control of renin release in heart failure have not been investigated. Accordingly we studied conscious dogs after volume overload (arteriovenous fistula) or chronic myocardial infarction. Acute infusion of nitroprusside was used to test the renin response to arterial hypotension and decreased central blood volume. Hydralazine and prazosin administration were used to test the response to chronic vasodilator administration. After 4 weeks of volume overload or 3 weeks after myocardial infarction, the renin response to a graded hypotensive stimulus was blunted. After 7 days of hydralazine or prazosin administration, plasma renin activity remained elevated and blood volume increased from baseline values. Our results indicate a decrease in the neural feedback control of renin release after chronic volume overload or myocardial infarction. However, chronic vasodilator administration still resulted in sustained augmented renin secretion and an increase in blood volume.

[Servo-ventilator 900 B with modified registration site for measuring the ventilation pressure. A possibility for reducing the inspiratory resistance during SIMV (author's transl)]

The inspiratory resistance, which a patient has to overcome while doing SIMV and CPAP with a Servoventilator 900 B, can be lowered by a simple modification of the ventilator. This modification is done by measuring the ventilation-pressure at the patients side of the humidifier. Measurements of pressure and flow demonstrated that, with a flow of 11 s-1 a 66%-reduction of the inspiratory resistance can be achieved.

[Electronic data processing in anaesthesia. Development of a data collection form and organisation of data collection (author's transl)]

We report on the development of a data collection form for anaesthesia. The difference between this form and the previously published recommendations is that it does not require any coding of data prior to collection. The anaesthetist completing the form needs no knowledge of data processing. Qualitative data have only to be marked, while quantitative data must be entered as such. So far, more than 90,000 anaesthesias have been collected with the form presented, therefore usefulness may be assumed.