[A juvenile case of radiation-induced meningioma two years after radiation for craniopharyngioma]

The patient was a 7-year-old boy who received radiation therapy of 50 Gy after total gross removal of a craniopharyngioma. After two years a follow up CT scan showed a new enhanced lesion in the right temporal tip within the previous irradiation field. Total removal of the tumor was performed and its histological examination showed it to be an atypical meningioma. This atypical meningioma satisfied Cahan's criteria. So we diagnosed this atypical meningioma as radiation-induced meningioma. Immunohistochemically this meningioma stained for Vimentin. An electron-microscopical examination showed neither desmosome nor interdigitation. The score of Ki-67 and BrdU-L. I. was very small. Compared with previously reported juvenile radiation-induced meningioma, the latency was very short. The patient received growth hormone (GH) replacement therapy. We suspected relation between GH replacement therapy and short latency. He was discharged without any new neurological deficits and we haven't detected tumor recurrence for two years.

Propentofylline administered by microdialysis attenuates ischemia-induced hippocampal damage but not excitatory amino acid release in gerbils

Systemic administration of propentofylline (PPF), an adenosine uptake inhibitor, has been demonstrated to protect CA1 pyramidal cells from death following transient cerebral ischemia in gerbils. In order to examine the direct effects of this inhibitor, we tested whether or not PPF administered into the hippocampus in situ through a microdialysis probe could attenuate ischemia-induced excitatory amino acid (EAA) release and prevent subsequent death of CA1 pyramidal cells in the gerbil. The EAA release and death of CA1 pyramidal cells observed in the hippocampus were compared with those in the contralateral hippocampus of the same animal into which vehicle alone was administered. The results indicated that pre- as well as post-treatments with PPF inhibited the death of CA1 pyramidal cells after 5-min ischemia in a dose-dependent manner, but did not significantly alter the EAA release during ischemia and reperfusion in the same animals. While the neuroprotective effect of PPF against ischemic damage has commonly been ascribed to attenuation of EAA release during ischemia, other actions of adenosine such as those influencing the synaptic responses, neuronal excitation, and local cerebral circulation, or as yet unidentified actions may be involved in the observed neuroprotective effects of PPF.

Attenuation of hemispheric swelling associated with acute subdural hematomas by excitatory amino acid antagonist in rats

Acute subdural hematoma (ASDH) gives rise to a mass effect not only by itself but also through unilateral hemispheric swelling. The present study tested the hypothesis that hemispheric swelling is mediated by mechanisms which involve excitatory amino acids (EAAs). After removal of the subdural clot, introduced by homologous blood (0.1-0.2 ml), the % brain water was determined from the formula: ((wet weight--dry weight)/wet weight) x 100. The % brain water of the left hemisphere was significantly greater than that of the right hemisphere during the initial 6 hours after induction of ASDH in animals injected with 0.2 ml blood. A less marked but significant increase was observed in the animals injected with 0.1 ml blood. Systemic pretreatment with kynurenic acid (KYN; 800 mg/kg, i.p.), a broad-spectrum EAA antagonist, attenuated the increase in % brain water in the animals injected with 0.2 ml blood. In order to determine the changes in cerebral metabolism induced by the model of ASDH employed in the present study, we measured the cortical cytochrome oxidase (CYO) activity, a marker of mitochondrial respiration, in a separate group of animals. The CYO activity estimated densitometrically from the histochemical staining was not significantly altered in the animals injected with either 0.1 or 0.2 ml blood, suggesting absence of ischemia. These results indicated that the hemispheric swelling associated with thin ASDHs may be partially mediated by mechanisms other than ischemia, in which EAAs appear to be involved.

Differing effects of vasopressin on regional cerebral blood flow of dogs following intracisternal vs. intra-arterial administration

We investigated the differential effect of the intracisternal and intraarterial administration of vasopressin on the regional cerebral blood flow (rCBF) in the parietal cortex of dogs. Regional CBF, velocity and blood volume were assayed by laser flowmetry. The intracisternal injection of 1 nmol vasopressin significantly increased the rCBF and velocity, without affecting blood volume. However, the intravertebral arterial injection of 1 nmol vasopressin significantly decreased the rCBF and velocity. This discrepancy can be explained by a difference in the affected vasculature; large blood vessels in the subarachnoid space vs. whole cerebral vascular system. The intracisternal and intraarterial injection of the nitric oxide inhibitor NG-monomethyl-L-arginine reduced the rCBF from the base line, and significantly suppressed the rCBF elevation induced by vasopressin. The effect of vasopressin may be considered as the summation of the increased flow from the dilated large vessels via the release of nitric oxide from the endothelium, and of the decreased flow from the contracted small vessels.

Fundamental patterns and characteristics of the laser-Doppler skin blood flow waves recorded from the finger or toe

Three different components, Basic Wave (BW), Cardiac Wave (CW) and Reflex Wave (RW), among the laser-Doppler (L-D) skin blood flow waves on the finger- or toe-tip, were studied in 32 healthy volunteers. The cycle of the rhythmic BW was 8.1 +/- 1.7.min-1 and was independent of respiratory movements. The BW was synchronous with the baseline fluctuation in the digit-photoplethysmogram. Power spectral analysis of rhythmic fluctuations in the simultaneously recorded R-R interval on ECG, systolic blood pressure, and L-D skin blood flow disclosed that the BW was correspondent with the Mayer wave, i.e., low frequency component. The cycle of the CW was consistent with the heart rate and was superimposed on the BW. The RW was a transient marked reduction in blood flow, which was induced by a deep inspiration or various sensory stimuli. A sympathetic skin response on the palm and a venoconstrictive response on the occluded arm were observed concomitantly with the RW. Good synchronization was observed in each component of the L-D skin flow waves between the fingers and toes. These findings suggest that the BW and the RW on the finger- or toe-tip are predominantly driven by tonic and reflex phasic activities of descending sympathetic outflows via the supraspinal center, respectively.

[Studies of emergency cardiopulmonary bypass (ECPB) for cardiopulmonary-cerebral resuscitation--(3). Neurological outcome and pathological changes of the brain]

Neurological outcome and pathological changes of the brain were studied in 5 female mongrel dogs, which were subjected to normothermic ventricular fibrillation (Vf) cardiac arrest of 15 min and resuscitated by using cardiopulmonary bypass through the femoral artery and veins (F-F bypass). Spontaneous circulation was restored by one or two defibrillating countershocks in all 5 dogs 5.2 +/- 1.1 (mean +/- SD) min after initiation of the F-F bypass. The F-F partial bypass was continued for 164 +/- 30 min under mild hypothermia. After weaning from the bypass, intensive care including controlled ventilation was carried out for the subsequent 6 to 36 h. Intermittent slow waves appeared on the electroencephalogram 62.8 +/- 11.6 min after initiation of the F-F bypass resuscitation and continuous waves at 145.6 +/- 27.5 min. Soon after extubation, the animals barked, moved the forelegs and could drink water. Neurological deficit scores (normal: 0, brain death: 500) improved to become below 100 except in 1 dog. However, macroscopic examination of the brain in 2 dogs with prominent recovery disclosed atrophy of the central gyrus and microscopic examination revealed typical ischemic injuries of the vulnerable neurons at the cerebellum, hippocampus and cerebral cortex in the frontal lobe.

Poly A-linked colorimetric microtiter plate assay for HIV reverse transcriptase

An assay for detection of the reverse transcriptase (RT) of the human immunodeficiency virus (HIV) was developed using poly A linked to microtiter plate with colorimetric detection of incorporated biotin deoxyuridine triphosphate (biotin-dUTP). During the RT reaction, biotin-dUTP was incorporated into oligodeoxythymidylic acid (oligo-dT) which had been hybridized with poly A. At the detection step, horseradish peroxidase conjugated streptavidin was added, followed by the reaction of a colorimetric substrate for this enzyme. This method was contrasted with the two standard isotopic RT assays. There was excellent correlation between the colorimetric RT assay and each of two isotopic RT assays for both detection and quantification of avian myoblastosis virus reverse transcriptase (AMV-RT) and of HIV RT in human lymphocytes infected in vitro with HIV-1. The total assay required for performing the colorimetric assay, including the RT reaction, was 40 min.

Simultaneous laser-doppler flowmetry of canine spinal cord and cerebral blood flow: Responses to $$Pa_{CO_2 } $$ and blood pressure changes

We observed the relative changes of both spinal cord blood flow (local SCBF) and local cerebral blood flow (local CBF) using independent laser-Doppler flowmeters (LDF) in 12 dogs under N2O(50%)-O2-enflurane(1.0%) anesthesia. The dorsal surface of the lumbar spinal cord and the parietal surface of the brain were partially exposed. Two fine LDF probes were placed between the exposed surfaces and the dura maters at each site. Both local SCBF and local CBF decreased simultaneously with hyperventilation and increased with hypoventilation within several seconds. The local SCBF responses to PaCO2 changes were similar in direction and degree as those of the local CBF. Autoregulation of local SCBF to arterial blood pressure (ABP) changes was abolished, though that of the local CBF was still recognized in a blunted fashion within a mean ABP range of 50 to 150 mmHg.

[Emergency cardiopulmonary bypass (ECPB) for cardiopulmonary-cerebral resuscitation; (2). Physiologic changes]

After normothermic ventricular fibrillation (Vf) cardiac arrest of 15 min, 15 female mongrel dogs received conventional cardiopulmonary resuscitation (CPR) for 3 min and then cardiopulmonary bypass through the femoral artery and veins (F-F bypass). Cardiac beat did not return in any dogs during the initial 3-min CPR. Spontaneous circulation was restored by defibrillation 5.2 +/- 3.8 (mean +/- SD) min after the initiation of the F-F bypass in all dogs except in one with bypass trouble. Life-threatening ventricular dysrhythmias appeared in 8 of the 14 dogs (57%). Eleven of the 14 dogs (79%) were successfully weaned from the F-F bypass. Spontaneous respiration and circulation remained stable for the subsequent 1-h observation period in 8 dog (57%). The values of cardiac output measured just before weaning from the bypass and 30 to 60 min after weaning were significantly lower than those before inducing Vf (n = 5). On the electroencephalogram, intermittent burst waves reappeared 90.0 +/- 24.7 min after the initiation of resuscitation and EEG showed continuous waves 130.7 +/- 28.1 min (n = 7) after the initiation of resuscitation. The values of blood glucose, lactate and potassium 5 to 15 min after the initiation of F-F bypass were significantly higher than those before induction of Vf, while the values of hemoglobin, hematocrit, platelet and serum protein decreased significantly (n = 14).

[Transdermal application of 10% lidocaine-gel for management of pain associated with herpes zoster]

We have developed transdermally applicable 10% lidocaine aqueous gel containing an absorption promoter and applied it for 15 patients suffering from severe pain in acute or subacute phase of herpes zoster. The patients, consisting of 7 males and 8 females with a mean age 58.5 +/- 13.0 (SD) yrs, had skin eruptions of herpes zoster for the past 2 months. Lidocaine-gel was applied locally to the diseased skin with or without an occlusive dressing. In 14 of the 15 patients (93%), a remarkable reduction of pain (below 10% of pretreatment level) was obtained after 9.9 +/- 5.6 (SD) times of lidocaine-gel treatments. There was no adverse systemic reactions or local skin damages. None of them developed post-herpetic neuralgia. The lidocaine-gel treatment appears to be very useful for reduction of pain associated with acute or subacute phase of herpes zoster.

Detection of human immunodeficiency virus (HIV) by colorimetric assay for reverse transcriptase activity on magnetic beads

A colorimetric assay for detection of reverse transcriptase (RT) of the human immunodeficiency virus (HIV) was developed using oligodeoxythymidylic acid (oligo-dT)-linked magnetic beads and digoxigenin-deoxyuridine triphosphate (dig-dUTP). During the RT reaction, dig-dUTP was incorporated into oligo-dT which had been hybridized to polyadenylic acid [poly (A)]. At the detection step, an alkaline phosphatase-conjugated antibody to digoxigenin was added, followed by the addition of a colorimetric substrate for this enzyme. This method showed excellent correlation with the isotopic RT assay, which used tritiated thymidine triphosphate ([3H]dTTP), for detection of purified avian-myeloblastosis-virus RT (AMV-RT). This assay also demonstrated close correlation with the isotopic RT assay using human peripheral-blood lymphocytes infected in vitro with HIV. This colorimetric RT assay offers important advantages over the conventional radioactive RT assays with respect to its simplicity, safety and cost. The total assay time, including the RT reaction step, was less than 1 h, and therefore provides a reliable rapid assay for detection and quantification of HIV.

An exon-trapping system with a newly constructed trapping vector pEXT2; its application to the proximal region of the human chromosome 21 long arm

We have developed an exon-trapping system with a newly constructed trapping vector containing multiple cloning sites (designated pEXT2). The system revealed high sensitivity for trapping a control exon from several hundred kbp of DNA. We have applied the system to the cosmid clones located on human chromosome 21p11-q21, and identified two fragments highly homologous to neurofibromatosis 1 (NF1) gene and a clearly transcribed fragment hybridized with approximately 1.6 kb RNA from human brain and human glioblastoma A172 cell.

Sequence-tagged NotI sites of human chromosome 21: sequence analysis and mapping

We isolated and analyzed 19 NotI site-containing clones specific for human chromosome 21. The overall process consisted of selective isolation of NotI site-containing clones from flow-sorted chromosome 21 libraries, selection of independent clones by their restriction patterns and nucleotide sequences, and assignment of the clones to chromosome 21. Sequence analysis showed that the regions around the NotI sites had features typical of CpG islands, such as extremely high GC content, high-frequency appearance of CpG dinucleotide sequences, and lack of methylation of these CpGs. PCR conditions for these extremely G + C-rich templates were optimized to establish these NotI sites as sequence-tagged sites.

Management of intractable pain with percutaneous epidural spinal cord stimulation: differences in pain-relieving effects among diseases and sites of pain

This study is a survey of the overall clinical results achieved with our pain treatment method, percutaneous epidural low-frequency (1.6-8.0 Hz) spinal cord stimulation. It examines the relationship between the effectiveness of epidural spinal cord stimulation (ESCS) and diseases or sites of pain. Continuous indwelling of the catheter electrodes in the posterior epidural space ranged from 3 to 67 days, and the duration of percutaneous ESCS varied from less than 1 wk to more than 1 yr. Complete pain relief (100%) was achieved during stimulation in 11.5% of the patients (52 of 454). Complete (100%) to partial (more than 30%) pain relief occurred in 71.1% of the patients. In six (1.3%) patients pain was aggravated by stimulation. Analgesics and/or sedatives were discontinued completely after treatment in 52 patients (11.5%) and reduced in 263 patients (57.9%). The number of patients who rated pain relief better than 50% was significantly more in carcinoma/sarcoma and causalgia (P < 0.001), and significantly less in postherpetic neuralgia and thromboangitis obliterans/arterial sclerosis obliterans (P < 0.001) than the average in all diseases. There was a significantly high responsiveness to ESCS in female patients in comparison to male patients (P < 0.05). Pain in the head/face, neck/upper extremities, and trunk responded more to ESCS than pain in the lower extremities. Alleviation of pain by ESCS was lower when the verbal pain score was high. There were no major complications in percutaneous ESCS. Thus, we have demonstrated that pain-alleviating effects of ESCS varies significantly by disease and site of pain, and that this simple percutaneous method can be used for a relatively long period.

A low frequency, high amplitude rhythmic fluctuation of laser-Doppler skin blood flow after subarachnoid phenol block

A 51-year-old male with a huge chondrosarcoma received subarachnoid dorsal root blocks with 10% phenol in glycerine to treat severe pain along the left leg. The dermatomes below the Th9 lost all somatic sensation on the left side after the nerve blocks, but the patient was not completely relieved from the pain. Laser-Doppler flowmetry on the toe of the left foot disclosed an increased blood flow and an abnormal fluctuation of the cutaneous capillary blood flow, i.e. a high amplitude rhythmic (HAR) wave with 2.5 to 3 cycles.min-1. The low frequency HAR wave persisted for the subsequent 3 months until a tingling sensation returned to the left leg. It would seem that some travelling roots of the sympathetic nerve were preserved from the chemical neurolysis and the remaining efferent and afferent nerve fibers were responsible for the persisting low frequency HAR wave and pain in the left leg.

Cardiopulmonary-cerebral resuscitation by using cardiopulmonary bypass through the femoral vein and artery in dogs

Twenty-seven dogs, divided into three groups, were subjected to a normothermic ventricular fibrillation (VF) cardiac arrest of 15 min and resuscitated by using cardiopulmonary bypass through the femoral veins and artery (F-F bypass). Group I (n = 15): Cardiac beating did not return in any dogs during an initial 3-min conventional cardiopulmonary resuscitation, but it returned 5.2 +/- 3.8 min (mean +/- S.D.) after the successive initiation of the F-F bypass in all dogs, except in one with bypass trouble. Intermittent burst waves appeared on the electroencephalogram and continuous waves returned, 90.0 +/- 24.7 min and 130.7 +/- 28.1 min after the start of resuscitation, respectively. Values of blood glucose, lactate and potassium 5-15 min after the F-F bypass were significantly higher than those before induction of VF, while those of blood pH, base excess, hemoglobin, hematocrit, platelet and serum protein decreased significantly. Group II (n = 7): Both local cerebral (CBF) and myocardial blood flow (MCBF) returned to the pre-arrest level soon after the initiation of the F-F bypass, even though spontaneous cardiac beating was not yet restored. Closed or open chest cardiac massage could not produce as much blood flow as the F-F bypass did. In the early stage of restoration of spontaneous circulation, temporary interruption of the bypass led to a decrease in both local CBF and MCBF. Group III (n = 5): Spontaneous circulation was restored in all five dogs 5.2 +/- 1.1 min after the institution of the F-F bypass, which was continued for 164 +/- 30 min under mild hypothermia. After intensive care for a subsequent 6-36 h, the animals barked, moved their forelegs and could drink water. The mean neurological deficit score (normal: 0, brain death: 500) was 100.6. However, macroscopic examination of the brain in two dogs with prominent recovery revealed atrophy of the central gyrus and microscopic examination revealed injuries of the vulnerable neurons of the brain.

Chemiluminescent enzyme-linked immunoassay for reverse transcriptase, illustrated by detection of HIV reverse transcriptase

A chemiluminescent assay for reverse transcriptase (RT) of the human immunodeficiency virus 1 was developed using biotin-labeled oligodeoxythymidylic acid (biotin oligo-dT) and digoxigenin-deoxyuridine triphosphate instead of tritiated thymidine triphosphate. After the RT reaction, the newly polymerized strand from biotin oligo-dT contained digoxigenin labels. This nucleotide was bound to a streptavidin-coated microtiter plate by the reaction to biotin. At the detection step, an alkaline phosphatase-conjugated antibody to digoxigenin was added, followed by the reaction of a chemiluminescent substrate for this enzyme. This method shows very close correlation with the isotopic assay using purified avian myeloblastosis virus reverse transcriptase (RT). This assay was also compared with the isotopic RT assay using lymphocytes infected in vitro with HTLV-IIIB and again demonstrated a close correlation. The total assay time after the RT reaction step was less than 100 min.

Dermal patch anaesthesia: comparison of 10% lignocaine gel with absorption promoter and EMLA cream

The analgesic effects of transdermally applied 10% lignocaine aquagel containing 3% glycyrrhetinic acid monohemiphthalate disodium (as an absorption enhancer) and EMLA cream were compared on the forearms of 34 adult volunteers in a double-blind fashion. The mean pinprick pain scores (graded by noting the number of painful pinpricks out of five) at 30, 60 and 90 min after application and 30 min after removal of the anaesthetics were 3.3 (0.3) (mean SE), 1.2 (0.3), 0.3 (0.1) and 0.3 (0.1) respectively, in the lignocaine gel group. Corresponding scores were 3.5 (0.3), 1.5 (0.3), 0.7 (0.2) and 0.1 (0.1) respectively, in the EMLA group. Insertion of a 26-gauge needle into the treated skin to a depth of 1 mm at 90 min after application was not painful in 91% of the volunteers in the lignocaine gel group and 88% of those in the EMLA group. There was no significant difference in any of the corresponding pain scores between the two groups.

[A case report of adenosquamous cell carcinoma of the stomach responding well to combination chemotherapy]

A 51-year-old man with unresectable adenosquamous cell carcinoma classified Borrmann type 3 of the stomach was treated with combination chemotherapy. The treatment consisted of two parts: intraabdominal administration of CBDCA (400 mg/body) during the operation, and transcatheteral intraabdominal infusion of CDDP(100 mg/m2) on day 1 and oral administration of UFT (400 mg/m2) on day 1 to 28 from a month after the operation. The latter therapy was performed every four weeks, and was administered two times. Primary gastric region was improved like a type II-C endoscopically, and metastatic lymphnode measuring 5 cm diameter disappeared on a computed tomography after the treatment. Thus, total gastrectomy was performed. No cancer cells were shown in both the resected stomach and dissected lymphnodes upon histological examination. Generally, patients with unresectable gastric cancer have a poor prognosis. But we concluded that the survival time and the quality of life in this patient were remarkably improved by the effective combination chemotherapy.

Clinical remission criteria for epithelial carcinoma of the ovary

After primary cytoreductive surgery 188 patients with epithelial ovarian cancer were treated with combination chemotherapy between 1986 and 1989 in the Tokai Ovarian Tumor Study Group. Clinical remission criteria were set in this study and patients were examined to determine if they were in remission or not. Forty-seven cases (25%) had no remission and 85.9% of them died within 20 months after primary surgery. Fifty-seven cases (30.3%) had a remission and a subsequent recurrence. Eighty-four cases (44.7%) had no recurrence and all are currently alive. Independent remission factors by multivariate analysis were higher stage (P = 0.018), clear-cell carcinoma (P = 0.0048), larger maximum residual tumor (P = 0.0023), and PVB therapy (P = 0.026). Independent recurrence factors were higher stage (P = 0.0012), serous cystadenocarcinoma (P = 0.0001), clear-cell carcinoma (P = 0.00409), and PVB therapy (P = 0.0499). A significantly high remission rate and low recurrence rate was achieved using PVB therapy. This criteria has value for the treatment of epithelial ovarian carcinoma. The disease-free survival rate after clinical remission was the same as that after a negative second-look laparotomy, which implies that a second-look laparotomy may be unnecessary in the management of epithelial carcinoma of the ovary.

Rapid increase in the number of androgen receptors following electrical stimulation of the rat muscle

The changes in the number of androgen receptors in rat gastrocnemius muscle following muscle contraction caused by electrical stimulation were investigated. The gastrocnemius muscle of one leg, which was selected at random for each rat, was stimulated with needle type electrodes, e.g. for 2 s at 10 V and 100 Hz, with 5-s intervals. The contralateral leg was left unstimulated as a control. One set consisted of ten such stimuli, followed by 5-min rest. Three sets every 2 days caused a statistically significant increase in muscle mass, the increase being about 2.5% after the 3rd day of stimulation, 4.4% after the 5th day, 5.9% after the 13th day and 8.3% after the 27th day compared with each control muscle (P < 0.001 in each case). The protein content also increased but the water content did not change. Stimulation over 4 weeks induced an increase in the area of the cross-section of the muscle fibres to about 30% more than that of the control muscles, though the total muscle fibre numbers were slightly, but significantly, reduced. Electromechanical properties supported the development of the muscle by stimulation, because the maximal isometric tetanic force and peak twitch force markedly increased in the stimulated muscle. The androgen receptors in the muscle cytosol fraction were determined by means of a binding assay involving [3H]methyltrienolone, which is an analogue of testosterone, the number having rapidly increased in the stimulated leg, when compared with that in the control leg, by about 25% after the 3rd day. The increase then slowed down, reaching a plateau after the 5th-day of stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of indeloxazine on hippocampal CA1 pyramidal cell damage following transient cerebral ischemia in the gerbil

The effects of indeloxazine on the ischemia-induced death of hippocampal CA1 pyramidal cells following transient cerebral ischemia were examined in the mongolian gerbil. Increased survival of CA1 pyramidal cells was demonstrated in animals pre- and post-treated with indeloxazine. Increased survival of CA1 pyramidal cells was, however, not demonstrated in animals post-treated but not pre-treated with indeloxazine. A previous study has demonstrated that indeloxazine increases the glucose and adenosine triphosphate (ATP) contents in the brain probably through an enhanced capability of oxidative phosphorylation. It has been reported that increases in the glucose and ATP contents in the brain before ischemia delay the onset of massive ionic fluxes during ischemia. The delay in onset of this ionic event may help to protect these cells from death. The present data suggest that energy state before ischemia may play an important role in the protective effect of indeloxazine.

Colorimetric detection for PCR amplified HIV-1 DNA using magnetic beads

A rapid and nonradioactive detection method for polymerase chain reaction (PCR) amplified HIV-1 DNA was developed using a colorimetric detection system. Hybridization between biotin-labeled amplified targets and digoxigenin-capture probes occurs in solution followed by efficient and rapid capture onto streptavidin-magnetic beads. The presence of the digoxigenin-capture probe hybridized with biotin-labeled targets is then detected by antidigoxigenin-alkaline phosphatase conjugates using a colorimetric substrate. This approach is highly sensitive and can detect less than 10 HIV targets prior to PCR in approximately 50 min.