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Biomedical subjects

C L Lee

Publications and source records attributed to C L Lee.

At least 163 records · Page 9Linked to original sources
PubMed1991

Operantly conditioned plasticity in spinal cord.

Recent work has shown that the monosynaptic pathway of the SSR can be operantly conditioned, and that a significant part of the plasticity responsible for the behavioral change resides in the spinal cord. The most likely sites of this activity-driven plasticity are the synapse of the Ia afferent neuron on the motoneuron and/or the motoneuron itself. Because the SSR pathway is the simplest and most accessible stimulus-response pathway in the vertebrate CNS, it may provide a valuable experimental model for elucidating activity-driven CNS changes responsible for learning.

Animals↗
PubMed1991

The purification and development of a radioimmunoassay for beta-core fragment of human chorionic gonadotrophin in urine: application as a marker of gynaecological cancer in premenopausal and postmenopausal women.

The beta-core fragment of human chorionic gonadotrophin (hCG) is a major part of the immunoreactive hCG-like material found in the urine of normal pregnant women. Patients with non-trophoblastic gynaecological malignancies have been found to have raised levels of urinary beta-core. We describe the purification of beta-core, the preparation of a polyclonal sheep antiserum and the development of radioimmunoassay. The minimum detection limit of this assay was 0.025 micrograms beta-core/l. There was no significant cross-reaction with the free alpha-subunit, hLH, hFSH and hTSH (less than 0.7%), and only partial cross-reaction with intact hCG and free beta-subunit of hCG (6.9 and 18%). Within-assay variability ranged from 2.03 to 12.5% and between-assay variability from 2.25 to 13.4%. The assay was applied to urine samples from 92 normal non-pregnant premenopausal women, 54 normal postmenopausal women and 65 women with active gynaecological disease (47 postmenopausal and 18 premenopausal). In normal premenopausal women the values ranged from less than 0.025 to 0.62 micrograms beta-core/l (median 0.043 micrograms beta-core/l). The values for normal postmenopausal women ranged from less than 0.025 to 0.64 micrograms beta-core/l (median 0.26 micrograms beta-core/l). Postmenopausal women with gynaecological malignancy had values which ranged from less than 0.025 to 4.0 micrograms/beta-core/l (median 0.31 micrograms beta-core/l); premenopausal women in this group had values which ranged from less than 0.025 to 1.15 micrograms beta-core/l (median 0.12 micrograms beta-core/l). On molecular sieve chromatography, the material found in the urine of normal postmenopausal women showed the physicochemical characteristics of authentic beta-core.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Posterior transfer of the adductors in children who have cerebral palsy. A long-term study.

Seventy-eight posterior transfers of the adductors of the hip in forty-two children who has spastic cerebral palsy were reviewed an average of 5.7 years after the operation (range, two to 14.6 years). The results were assessed on the basis of the patient's ability to walk, the range of motion of the affected hip or hips, and the radiographic measurements. In 88 per cent of the patients, the transfer was successful in improving or maintaining abduction, extension, functional walking, and stability of the hip. The failures were all in patients who were unable to walk and who had spastic quadriplegia. Tenotomy of the iliopsoas tendon at the time of the transfer procedure resulted in an improved range of motion of the hip.

Adolescent↗
PubMed1990

Role of 1q trisomy in tumorigenicity, growth, and metastasis of human leukemic B-cell clones in nude mice.

In order to investigate the association between various karyotypes of human tumor cells and biological behavior of tumors such as tumorigenicity, rate of growth, and the capacity to form metastasis, six chromosomally distinctive clones were isolated from an Epstein-Barr virus-transformed human chronic lymphocytic leukemic B-cell line which progressively grew and metastasized in irradiated nude mice. When inoculated into nude mice one clone (D10-1) with the karyotype of 46,XY,dup(1)(q11----q32) was more tumorigenic, grew faster, and produced more metastases than the other five clones. When mixtures of different clone-derived cells were grown in vitro or inoculated s.c. into nude mice the proportion of D10-1 cells was higher than their expected numbers in the cultures, s.c. tumors, and splenic and lymph nodal metastases. The growth and metastatic potential of the D10-1 clone were inhibited when cells from this clone were mixed with one or more clones that had slower growth. Duplication of 1q has been observed as a secondary aberration in human hematological malignancies and solid cancers. Our results demonstrate that duplication of the chromosome segment of 1q11----1q32 is associated with advantages in proliferation and metastasis formation.

Animals↗
PubMed1990

Comparison of prostate acid phosphatase with acid phosphatase isoenzymes from the lung and spleen.

Acid phosphatase was purified to electrophoretic homogeneity from human normal lung and spleen and was characterized biochemically and immunologically in comparison with prostate acid phosphatase (PAP). The apparent MW of lung acid phosphatase (LAP) and spleen acid phosphatase (SAP) was 110,000 and 100,000, respectively, similar to that of PAP (100,000). All three enzymes exhibited similar electrophoretic mobility, optimal pH, substrate, and inhibitor specificity, except that PAP dephosphorylated profoundly the phosphate group from tyrosine phosphate in phosphoangiotensin (19,700 fmol/mg/min), whereas only marginal activities were detected for LAP and SAP (19 and 73 fmol/mg/min, respectively). Amino acid analysis revealed more similarity between SAP and LAP than PAP and LAP or PAP and SAP. An immunological cross-reactivity among these three acid phosphatases was detected by polyclonal and monoclonal antibodies raised against purified PAP, although unique epitopes were detected on the PAP molecule. This study provides data explaining why conventional biochemical methods are not specific for PAP measurement and why immunologic methods still detect other acid phosphatases, as observed in clinical laboratory assays. The data also suggest the possibility of using a new substrate or antibody reagent for a more specific assay for PAP.

Acid Phosphatase↗
PubMed1990

Confocal scanning laser microscope images of hippocampal neurons intracellularly labeled with biocytin.

We have assessed the properties and usefulness of confocal scanning laser microscopy in the reflection mode for the study of neuronal morphology. In this mode, the confocal microscope detects the light reflected off the specimen as opposed to the light emitted by a fluorescent label. Neurons in slices of rat hippocampus were filled with biocytin and reacted sequentially with avidin-horseradish peroxidase and nickel-intensified diaminobenzidine (DAB/Ni). In all parts of the neuron the DAB/Ni reaction product produced a strong reflection signal in the confocal microscope. The stereo images revealed aspects of three-dimensional hippocampal cell morphology such as the conical shape of the dendritic fields and a characteristic branching pattern of the axon. Labelling neurons intracellularly is an established technique for identifying physiologically-characterized neurons. Recently, confocal microscopy has become a powerful method for examining the three-dimensional morphology of biological specimens. The resulting images in this paper show that reflection-mode confocal microscopy provides an excellent representation of the filled neurons in three dimensions and presents an opportunity for correlative electrophysiological and morphological studies and extension to the electron-microscopic level.

3,3'-Diaminobenzidine↗
PubMed1990

Monoclonal antibodies against Epstein-Barr virus transformed B lymphocytes from a CLL patient.

Immunization of BALB/c mice with EBV-CLL-1 cells, derived from Epstein-Barr virus transformed B lymphocytes from a chronic lymphocytic leukemia (CLL) patient, yielded 2 monoclonal antibodies (IgG1 Kappa and IgG2a Kappa) against a membrane antigen on a subset of normal B lymphocytes and non-Hodgkin's lymphomas. Immunofluorescence revealed strong reactivity of the antibodies with EBV-CLL-1 cells and with most lymphocytes in tonsil follicles, in the intestinal wall, around splenic arterioles and near Hassall's corpuscles in the neonatal thymus as well as with a small proportion of lymphocytes in some large reactive lymph node follicles, weak reactivity with 1/5 of peripheral blood B lymphocytes (PBL), and no reactivity with platelets, granulocytes and non-lymphoid tissues. PBL from 3 CLL patients showed weak staining of only larger cells. Intense fluorescence was observed in several non-Hodgkin's lymphomas of various histological types and in Burkitt's lymphoma lines but not in the 3 T lymphoblastoid and 12 nonlymphoid tumor lines examined. The antibodies precipitated Mr 22,000 and 33,000 bands from surface labeled RAJI or EBV-CLL-1 cells and cross-competed in a binding inhibition assay. The antibodies had approximately 6 million binding sites per EBV-CLL-1 or RAJI cell but were not cytotoxic. This high antigen-density and limited expression in normal cells may permit their use for immunocytological diagnosis and targeting cytotoxic agents and radionuclides against appropriate lymphoma cells.

Animals↗
PubMed1990

Composition of intact hormone and free subunits in the human chorionic gonadotrophin-like material found in serum and urine of patients with carcinoma of the bladder.

Ectopic-hCG production occurs in approximately 30% of urothelial cancers. However, the clinical features which might be expected to result from elevated hCG levels are rare. We now show that in six of seven metastatic and 20 of 21 localized (Ta-T4) positive hCG bladder cancer patients, only the free beta-subunit of hCG and its respective urinary breakdown product, beta-core, could be detected in clinical samples. Since only intact hCG is biologically active, this explains the discrepancy between biochemical and clinical findings.

Aged↗
PubMed1990

The clinical role of transoesophageal echocardiography.

The role of transoesophageal echocardiography (TEE) was evaluated in a consecutive series of 100 procedures performed in 86 patients (age 17-81, mean 56 years). All patients had prior transthoracic echocardiography (TTE). TEE was performed with a 5 MHz phased array transoesophageal transducer with pulsed wave Doppler and colour flow mapping capability. Forty-four per cent of patients received intravenous sedation and 36% received antibiotic prophylaxis. There were no complications of TEE. The TTE and TEE findings were compared. In patients referred for possible cardiac source of embolism, left atrial thrombi were detected in 8/27 TEE studies but in none of 27 TTE studies. In 12 patients with prosthetic valve dysfunction TEE distinguished prosthetic from periprosthetic regurgitation in 9/12 studies compared to 3/12 with TTE. In 11 patients with suspected aortic dissection TEE correctly detected dissection in all seven cases in which the diagnosis was subsequently confirmed, whereas TTE showed only equivocal findings in two cases. Vegetations were detected by TEE in 4/5 studies in patients with proven native valve endocarditis and by TTE in 2/5. No vegetations were detected by TTE or TEE in five studies in patients with proven prosthetic valve endocarditis. Compared with other investigations there were no false positive TEE studies and one possible false negative study. We conclude that TEE is a safe procedure which often provides additional clinical information to transthoracic echocardiography.

Adolescent↗
PubMed1990

Potential exposure and health risks of infants following indoor residential pesticide applications.

Air and surface chlorpyrifos residues were measured for 24 hours following a 0.5 percent Dursban broadcast application for fleas inside a residence. Two of the three treated rooms were ventilated following application. Maximum air concentrations were measured 3-7 hours post-application. Peak concentrations in the infant breathing zone were 94 micrograms/m3 in the nonventilated room and 61 micrograms/m3 in the ventilated room, and were substantially higher than concentrations in the sitting adult breathing zone. Concentrations of approximately 30 micrograms/m3 were detected in the infant breathing zone 24 hours post-application. Surface residues available through wipe sampling were 0.7-1.6 micrograms/cm2 of carpet on the day of application and 0.3-0.5 micrograms/cm2 24 hours post-application. Estimated total absorbed doses for infants were 0.08-0.16 mg/kg on the day of application and 0.04-0.06 mg/kg the day following application, with dermal absorption representing approximately 68 percent of the totals. These doses are 1.2-5.2 times the human No Observable Effect Level (NOEL). Exposures to cholinesterase inhibiting compounds following properly conducted broadcast applications could result in doses at or above the threshold of toxicological response in infants, and should be minimized through appropriate regulatory policy and public education.

Air Pollutants↗
PubMed1990

Immunobiological study of interferon-gamma-producing cells after staphylococcal enterotoxin B stimulation.

Staphylococcal enterotoxin B (SEB) induced the production of human interferon-gamma (hIFN-gamma) in peripheral blood mononuclear cells (PBMC). Using specific mouse monoclonal antibodies (mAb) to hIFN-gamma, the patterns of cytoplasmic fluorescence in the PBMC from five individuals were studied. Discrete polar bodies in a ring-formation adjacent to the nuclear membrane was the most frequently observed fluorescent pattern throughout the 76-hr observation period. Additional and different fluorescent patterns such as multifocal and diffused cytoplasmic, as well as granular fluorescence over the whole cytoplasm, may appear during the late induction period (50-76 hr). By using an immunogold-silver (IGS) enhancement method to label cell-surface antigens, it was possible to detect the presence of CD3, CD4, CD25 and OKT11 marker in 55%, 54%, 77%, and 71% of the IFN-gamma producer cells, respectively. Monensin and carboxylcyanide m-chlorophenyl-hydrozone (CCCP) are ionophores known to interrupt subcellular transport of a number of secretory proteins. When monensin or CCCP was added to the induced cultures 2-3 hr before harvests, an increase in the intensity of cytoplasmic fluorescence in IFN-gamma-producing cells was observed; a greater than 10-fold enhancement in the sensitivity of immunostaining was demonstrated in these preparations.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗
PubMed1990

Posterior spinal fusion: allograft versus autograft bone.

The effectiveness of allograft bone for posterior spinal fusion in neuromuscular scoliosis is controversial. Thirty patients with cerebral palsy, treated with posterior spinal fusion, were divided into two groups. Group 1 consisted of 18 patients treated by posterior spinal fusion using autogenous bone graft. Group 2 consisted of 12 patients treated by posterior spinal fusion using freeze-dried allograft bone. The average preoperative curve of 70 degrees in Group 1 was corrected to 35 degrees (50% correction). At 3.2 years average follow-up, the curves averaged 51 degrees (46% loss of correction). The average preoperative curve of 80 degrees in Group 2 was corrected to 39 degrees (51% correction). At 3.5 years average follow-up, the curves averaged 54 degrees (38% loss of correction). Anesthesia time decreased from 344 to 281 minutes (p less than 0.05), and intraoperative blood loss decreased from 2730 to 1740 ml (p less than 0.025) when allograft bone was used as a substitute for autograft bone. Freeze-dried allograft bone is a readily available, safe, and effective substitute for autogenous bone graft in patients with cerebral palsy undergoing posterior spinal fusion.

Adolescent↗
PubMed1990

Computer application in a general practice.

Computer application in General Practice has improved the standard of healthcare. Computers have been used in the clinic for general administration and accounting. A Clinic Management System in addition can be used in most of the functions required in the running of a clinic. It will be able to generate useful data to help the doctors make sound decisions based on valid, up-to-date information. Communications and accessing of medical databases can be made available with a central network such as MediNet. There are currently no well developed medical record management systems suitable enough for implementation in general practice. Computerisation of the general practice will require careful planning and gradual implementation using a reliable application software backed by good support from the original developer. Commitment to continued research and development of the software will ensure that the implemented system will not be outdated.

Ambulatory Care Information Systems↗
PubMed1989

Memory traces in spinal cord produced by H-reflex conditioning: effects of post-tetanic potentiation.

Operant conditioning of the wholly spinal, largely monosynaptic triceps surae H-reflex in monkeys causes changes in lumbosacral spinal cord that persist after removal of supraspinal influence. We evaluated the interaction between post-tetanic potentiation and these memory traces. Animals in which the triceps surae H-reflex in one leg had been increased or decreased by conditioning were deeply anesthetized, and monosynaptic reflexes to L6-S1 dorsal root stimulation were recorded before and after tetanization from both legs for 3 days after thoracic cord transection. Animals remained anesthetized throughout and were sacrificed by overdose. Reflex asymmetries consistent with the effect of H-reflex conditioning were present after transection and persisted through the 3 days of study. Tetanization affected conditioned leg and control leg reflexes similarly. This finding suggests that, while post-tetanic potentiation and probably H-reflex conditioning alter Ia synaptic transmission, the two phenomena have different mechanisms.

Animals↗