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Biomedical subjects

M C Ng

Publications and source records attributed to M C Ng.

At least 19 recordsLinked to original sources
PubMed2001

Diabetes mellitus--a special medical challenge from a Chinese perspective.

As we enter the new millennium, Asia is being hit by an epidemic of diabetes and its related diseases. The rising prevalence of young onset diabetes which is closely associated with obesity and genetic factors as well as the increased propensity to develop kidney disease are special challenges in the management of Chinese diabetic patients. Although diabetic patients have earlier mortality and increased risks for micro and macrovascular complications, there is strong evidence that these devastating complications can be largely prevented by patient education, periodic assessments and use of appropriate therapeutic agents to optimize metabolic control and improve cardiovascular risk factors. However, a multidisciplinary approach is often required to deliver these complex disease management protocols. Hence, it is not surprising that large scale studies often revealed substandard diabetes management in both the hospital and community settings. This is often due to a combination of factors such as non-adherence to recommended guidelines both by patients and doctors as well as the 'non-urgent' and 'silent nature' of diabetes and its complications. To minimize the impacts of diabetes on quality of life, society productivity and utilization of health care resources, concerted efforts between health care professionals and public bodies are urgently needed to increase awareness, improve standards of care and develop better diagnostics and treatment modalities.

Asia↗
PubMed2001

Association of retinopathy with a microsatellite at 5' end of the aldose reductase gene in Chinese patients with late-onset Type 2 diabetes.

Recent experimental data suggest that a microsatellite polymorphism at 5' end of the aldose reductase gene may be associated with the development of diabetic retinopathy. In the present study, we examined the allele distribution of the polymorphism in 384 Hong Kong Chinese patients who had late-onset (age at diagnosis > or =35 years) Type 2 diabetes, but no clinical evidence of cataract. Approximately 17% of them (n = 64) had retinopathy. The patients with retinopathy were older (52 +/- 11 years vs. 60 +/- 9 years, p < 0.01) and had a higher HbA1c (8.9 +/- 2.2% vs. 7.7 +/- 2.0%, p < 0.01 with adjustment for age) than those without the complication. Amongst all of the patients, we detected 10 microsatellite alleles and found that allele Z-4 was overpresented in those with retinopathy (9% vs. 4%, p < 0.05). There were no significant differences in allelic distributions of the major alleles Z + 2, Z, and Z-2, which accounted for more than 80% of the overall frequency, between the two groups of patients. Using multiple logistic regression analysis (R2 = 0.17, p < 0.01), we found that age (p < 0.01) and HbA1c (p < 0.05) were associated with retinopathy. In conclusion, our data suggest that the occurrence of diabetic retinopathy in the Chinese population may be influenced by clinical and metabolic factors. The aldose reductase gene may be implicated, but is not likely to play a major role.

Adult↗
PubMed2001

Familial early-onset type 2 diabetes in Chinese patients: obesity and genetics have more significant roles than autoimmunity.

OBJECTIVE: We examined the prevalence of different forms of diabetes in Hong Kong Chinese patients with familial early-onset type 2 diabetes and compared their clinical features with patients with familial late-onset type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 145 young patients with early-onset diabetes (age and age at diagnosis < or = 40 years) and a family history of diabetes were studied. They were screened for mutations in the genes encoding glucokinase, hepatocyte nuclear factor (HNF)-4alpha, and HNF-1alpha. The mitochondrial DNA A-->G at nucleotide 3243 (mt3243) and amyLin S20G mutations were studied, and antibodies to GAD (anti-GADs) were also examined. RESULTS: The prevalence of putative diabetogenic gene mutations and autoimmune markers were 4% for glucokinase, 0% for HNF-4alpha, 5% for HNF-1alpha, 3% for mt3243, 2% for amylin 520G, and 4% for anti-GAD. Compared with late-onset patients, the patients with early-onset diabetes had a higher prevalence of a parental history of diabetes and were generally more obese. When classified by obesity indexes (BMI and waist circumference), the obese patients, especially those with early-onset diabetes, had a clustering of cardiovascular risk factors and increased rates of retinopathy and albuminuria. CONCLUSIONS; Genetic factors (up to 14%) and obesity (55%) play more significant roles than autoimmunity (4%) in familial type 2 diabetes in young Chinese patients. The significance of obesity-related genes and other gene-gene and gene-environment interactions in these young patients remains to be determined.

Adult↗
PubMed2000

Mitochondrial DNA A3243G mutation in patients with early- or late-onset type 2 diabetes mellitus in Hong Kong Chinese.

BACKGROUND AND OBJECTIVES: The mitochondrial DNA A to G mutation at nucleotide 3243 (mt3243) is associated with a subtype of diabetes characterized by maternal transmission and deafness. We have previously reported a 2.7% prevalence of this mutation in a cohort of young patients with either type 1 or type 2 diabetes. In this study, we aimed to confirm this finding by examining for the prevalence of this mutation in a large-scale study. SUBJECTS AND METHODS: Nine hundred and six unrelated Chinese patients with type 2 diabetes and 213 nondiabetic controls were studied. The presence of mt3243 mutation was determined by polymerase chain reaction amplification and ApaI digestion. RESULTS: This mutation was found in four of 133 (3.0%) patients with early onset (</= 40 years) diabetes who also had a positive maternal family history, and in one of 348 (0.3%) patients with late-onset (> 40 years) diabetes and no family history. Basal pancreatic beta-cell function, as assessed by fasting plasma C-peptide, was variable amongst mutation carriers, and did not correlate with the level of heteroplasmy of mutation. CONCLUSIONS: In agreement with most studies, our results suggest that despite the high prevalence of positive maternal family history of diabetes amongst our type 2 diabetic patients, mt3243 mutation was not a major cause of diabetes in either early- or late-onset diabetic patients in Hong Kong. The role of other genetic, environmental and intrauterine factors needs further investigation.

Adult↗
PubMed2000

Presence of mitochondrial tRNA(Leu(UUR)) A to G 3243 mutation in DNA extracted from serum and plasma of patients with type 2 diabetes mellitus.

AIMS/BACKGROUND: An A to G substitution at base pair 3243 in the mitochondrial tRNA(Leu(UUR)) gene (mt3243) is commonly associated with maternally inherited diabetes and deafness, and other diseases. It is possible that cell free mitochondrial DNA exists in serum and plasma from these patients, and these samples might be a source of material for the detection of such mutations. METHODS: Sixteen patients with type 2 diabetes mellitus and 25 healthy subjects were tested for the 3243 mutation by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. Plasma and serum from the 41 subjects were tested blind, without knowledge of the final diagnosis. RESULTS: PCR amplification of the mtRNA(Leu(UUR)) region in mitochondrial DNA (mtDNA) in serum samples revealed the presence of mtDNA in all samples. After ApaI digestion of the amplified DNA fragments, mt3243 was detected in the serum and plasma samples of the seven patients with diabetes who had previously been found to have this mutation in their leucocyte DNA. None of the serum/plasma samples from the healthy subjects or those patients negative for mt3243 in their leucocytes had this mutation (p < 0.001). In addition, the degree of heteroplasmy of mt3243 appeared to be higher in serum and plasma samples than in leucocytes among mt3243 carriers (p < 0.05). CONCLUSIONS: Therefore, mtDNA and associated mutations are present and detectable in serum and plasma. Plasma and serum might be alternative sources for the molecular diagnosis of mt3243 associated diabetes mellitus, as well as other mitochondrial mediated diseases.

Adult↗
PubMed2000

Genetics of type 2 diabetes mellitus.

Type 2 diabetes mellitus is a heterogeneous disease that is caused by both genetic and environmental factors. Only a minority of cases of type 2 diabetes are caused by a single-gene defect, such as maturity-onset diabetes of youth (mutated MODY gene), syndrome of insulin resistance (insulin receptor defect), and maternally inherited diabetes and deafness (mitochondrial gene defect). The genetic component of the more common form of type 2 diabetes is probably complex and involves the interactions of multiple genes and environmental factors. The candidate gene approach has identified several genes that regulate insulin signalling and secretion, but their contributions to diabetes are small. Recent genome scan studies have been conducted to identify major susceptibility loci that are linked with type 2 diabetes. This information would provide new insights into the identification of novel genes and pathways that lead to this complex disease.

Amyloid↗
PubMed1999

Effects of estrogen on the condylar cartilage of the rat mandible in organ culture.

PURPOSE: The effects of estrogen on bone have been well documented. However, very little is known about the regulatory role of estrogen on cartilage and, in particular, the secondary cartilage of the mandibular condyle. The aims of this study were to determine whether estrogen receptors are present in the condylar cartilage of the rat mandible and to assess the effect of varying 17beta-estradiol (E2) concentrations on the proteoglycan content of this tissue. MATERIALS AND METHODS: Mandibular condyles of 16 female Sprague-Dawley rats were resected. Eighteen of these condyles were divided into three groups and the condylar cartilage was removed and placed in organ culture for 4 days with media containing different concentrations of estrogen: 10(-11) mol/L, 10(-8) mol/L, and 10(-6) mol/L. The cartilage then was analyzed for proteoglycan content along with six specimens not passed through the organ culture. Six intact mandibular condyles also were resected and placed in organ culture with the same varying E2 concentrations, and the condylar cartilage was analyzed for estrogen receptors along with two condyles not passed through the culture system. RESULTS: Estrogen receptors were evenly distributed within the chondroblastic and hypertrophic zones in the control group and the group with 10(-11) mol/L E2. With E2 concentrations of 10(-8) mol/L and 10(-6) mol/L, there was a qualitative decrease in hypertrophic chondroblasts, thickness of the condylar cartilage, and a significant decrease in proteoglycan content. CONCLUSIONS: This study shows the presence of estrogen receptors in the secondary cartilage of the rat mandibular condyle. Estrogen has the potential to cause a decrease in extracellular matrix and thickness of this cartilage.

Analysis of Variance↗
PubMed1999

Molecular genetics of diabetes mellitus in Chinese subjects: identification of mutations in glucokinase and hepatocyte nuclear factor-1alpha genes in patients with early-onset type 2 diabetes mellitus/MODY.

AIMS: To examine the prevalence of identified MODY-related genes in Chinese subjects with early onset Type 2 diabetes mellitus and a positive family history of diabetes and to look for possible associations between the gene mutations and the development of diabetes. METHODS: Ninety-two unrelated Chinese subjects with diabetes diagnosed before the age of 40 years who had a positive family history of diabetes were screened for mutations in hepatocyte nuclear factors (HNF-1alpha and HNF-4alpha) and glucokinase genes by direct sequencing. The family members of patients with mutations and 100 healthy controls were also examined. RESULTS: Mutations in the HNF-1alpha and the glucokinase genes were found in 5% and 3% of the diabetic subjects, respectively but no mutations were found in the coding region of the HNF-4alpha gene. Three mutations found in the glucokinase gene were novel missense mutations (I110T, A119D and G385V). The mutations in the HNF-1alpha gene were also new and included four missense mutations (G20R, R203H, S432C, I618M) and one splice acceptor site mutation (IVS2nt-1G-->A). Patients with mutations in these genes were clinically heterogeneous with respect to phenotype and basal pancreatic beta cell function. CONCLUSIONS: Genetic factors such as mutations in the HNF-1alpha and glucokinase genes may be important in the development of diabetes in Chinese people, especially when the disease is of early onset.

Adolescent↗
PubMed1998

Calbindin-D28k buffers intracellular calcium and promotes resistance to degeneration in PC12 cells.

The calcium-binding protein calbindin-D28k (CB) has been hypothesized to function, in part, as a neuroprotective protein. CB is localized within nerve cells that are often less vulnerable to degeneration in patients with Alzheimer's disease and Parkinson's disease, and cells containing CB can buffer intracellular calcium concentrations ([Ca2+]i). The present study was designed to directly test the hypothesis that CB can protect cells from degeneration by reducing [Ca2+]i. PC12 cells, transfected to express different levels of CB, were found to be significantly less vulnerable to degeneration caused by serum withdrawal, glutamate, and the neurotoxin 1-methyl-4-phenylpyridinium (MPP+). However, CB did not protect cells from degeneration caused by the calcium ionophore A23187. CB-transfected cells exhibited reduced elevations in [Ca2+]i following treatment with bradykinin, or ATP compared to non-CB-containing cells. These data indicate that CB can protect cells from degeneration caused by certain conditions, and it reduces elevations in [Ca2+]i caused by influx from extracellular sources.

1-Methyl-4-phenylpyridinium↗
PubMed1997

Calbindin-D28k in nerve cell nuclei.

Calbindin-D28k is a member of the large EF-hand family of calcium-binding proteins, that is believed to function, in part as a cytosolic calcium buffer. Recent studies have demonstrated that cells containing Calbindin-D28k are protected from degeneration caused by conditions that elevate intracellular calcium concentrations. Since its initial discovery in 1966, Calbindin-D28k has been localized in the cytoplasm of many neuronal populations, but its nuclear localization has been uncertain. Using light and electron microscopic immunohistochemistry, and nuclear fractionation methods, we demonstrate localization of Calbindin-D28k not only in the cytoplasm, but also in the nucleus of rodent midbrain dopaminergic neurons and cerebellar Purkinje cells. The Calbindin-D28k immunoreactive staining intensity in the nucleus was routinely equal or greater than that in the cytoplasm. Since calcium signals are propagated to the nucleus, where they can regulate gene expression, the existence of nuclear Calbindin-D28k has important implications for cellular function.

Animals↗
PubMed1996

Urinary 6 beta-hydroxycortisol excretion in Hong Kong Chinese patients with hepatocellular carcinoma and other chronic liver diseases.

BACKGROUND: The biotransformation of xenobiotics into toxic metabolites by cytochrome P-450 has been implicated in carcinogenesis. This study investigated CYP3A4 activity, which metabolically activates procarcinogens such as aflatoxin B1, by measuring the urinary 6 beta-hydroxycortisol (6 beta OHF) to free cortisol (F) ratio in patients with hepatocellular carcinoma (HCC) and other chronic liver diseases. METHODS: One hundred forty-three controls and 150 patients with different liver diseases, including chronic liver disease (due to alcoholism and/or chronic hepatitis B virus infection), cirrhosis (any cause), and resectable and nonresectable HCC, were recruited. Twenty-four hour urine samples were collected for measurement of 6 beta OHF and free cortisol by an enzyme-linked immunosorbent assay (ELISA) and a radioimmunoassay, respectively. RESULTS: Patients with nonresectable HCC showed a significant increase in 6 beta OHF excretion as well as their 6 beta OHF/F ratio (P < 0.05) when compared with the controls and other liver disease groups including patients with resectable HCC. The nonresectable HCC group showed a bimodal distribution in the 6 beta OHF/F ratio. Using a ratio of 9 or more in all HCC patients, the sensitivity and specificity of using the 6 beta OHF/F ratio to predict nonresectability of HCC was 48.8% and 92.6%, respectively. CONCLUSIONS: Our results show an increase in mean CYP3A4 enzyme activity, reflected as an increase in the 6 beta OHF/F ratio, in Hong Kong Chinese with nonresectable HCC compared with those with resectable HCC and other liver diseases. Although the role of increased CYP3A4 activity in the aetiology of HCC is not known, our specificity and sensitivity estimates suggest that a high 6 beta OHF/F ratio indicates probable inoperability. However, a normal level is a poor predictor of resectability.

Adolescent↗
PubMed1996

Selective liver enzyme induction by carbamazepine and phenytoin in Chinese epileptics.

OBJECTIVE: Anticonvulsant drugs are known inducers of cytochrome P450 liver enzymes and it has been suggested that this induction increases susceptibility to paracetamol-induced hepatotoxicity. METHODS: We measured the percentage urinary recovery of paracetamol and its metabolites after a dose of 20 mg kg-1, and the excretion of 6 beta-hydroxycortisol as a ratio to urinary free cortisol (6 beta OHF/F) in Chinese epileptic patients maintained on long-term therapy with carbamazepine (n = 6) or phenytoin (n = 6). RESULTS: Compared to the healthy controls (n = 20), patients on phenytoin had significantly lower recoveries of mercapturic acid, cysteine and sulphate metabolites, but a higher recovery of glucuronide metabolites of paracetamol. The recoveries of paracetamol metabolites in patients on carbamazepine were not different from controls. In contrast, the 6 beta OHF/F was significantly higher in patients on carbamazepine (3-fold) or phenytoin (2-fold) compared to controls. Healthy control Chinese subjects metabolised paracetamol in a similar way to that reported in Caucasians, indicating that the risk for hepatotoxicity would be the same. Our findings in a group of Chinese patients on phenytoin were also similar to those previously reported in Caucasians on this drug. The apparent differences in the pattern of isoenzyme induction between the groups on phenytoin and carbamazepine require verification in larger studies. The data do not suggest an increased risk of paracetamol-induced hepatotoxicity in Chinese patients on anticonvulsants.

Acetaminophen↗
PubMed1996

The neurotoxin MPTP increases calbindin-D28k levels in mouse midbrain dopaminergic neurons.

The calcium-binding protein calbindin-D28k (CALB) has been localized in high concentrations in several neuronal populations within the central nervous system (CNS) and is believed to act as an intracellular calcium (Ca2+) buffer. There has been much interest and speculation concerning its potential neuroprotective function. However, there is little direct evidence linking CALB content of individual neurons to Ca2+ buffering ability, resistance to Ca(2+)-mediated excitotoxicity, or vulnerability to Ca(2+)-mediated degeneration. It is necessary to demonstrate these relationships on a cellular level so that more definitive conclusions can be made. We have utilized immunocytochemical and Western blot techniques to determine whether cellular CALB content is altered in the nucleus A10 dopaminergic region of the midbrain following administration of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our data demonstrate a significant increase in the CALB content of nucleus A10 neurons (up to 227 +/- 23% above control) 3 and 6 h after MPTP treatment. CALB elevation demonstrated both time and dosage dependence as 6-h groups exhibited larger increases than 3-h groups, and a 60 mg/kg dosage induced a larger increase than a 20 mg/kg dosage. These data support the hypothesis that MPTP is neurotoxic by causing increases in free intracellular Ca2+ and that increased CALB in the midbrain dopaminergic neurons is a protective response to elevated intracellular free Ca2+.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1996

PDGF-B producing cells and PDGF-B gene expression in normal gingival and cyclosporine A-induced gingival overgrowth.

It has been proposed that healthy gingiva is in a continuous state of wound repair. Thus, one might expect to find cells in normal gingiva producing growth factors associated with wound healing such as platelet-derived growth factor B chain (PDGF-B). One might also expect to find increased numbers of these cells or increased amounts of these growth factors in conditions which involve increased tissue volume such as drug-induced gingival overgrowth (DGO). The purpose of this study was to quantify PDGF-B gene expression and identify cells producing PDGF-B in normal gingiva and DGO. Cyclosporine A (CSA) was selected as a prototype of the overgrowth condition. Twelve patients with clinical CSA DGO and 12 patients with no DGO or history of drugs known to cause DGO were selected for study. Frozen sections of gingival specimens from these patients were subjected to in situ hybridization for PDGF-B mRNA. Positive cells were counted and expressed as mean +/- SEM cells/mm2 of lamina propria. Morphometric analysis revealed 6.2 +/- 1.9 cells/mm2 for control gingiva and 10.3 +/- 3.4 cells/mm2 for CSA DGO samples. There was no statistically significant difference between groups. PDGF-B gene expression was measured in these cells and expressed as mean +/- SEM silver grains/cells. There was a significant upregulation of PDGF-B gene expression in cells from the CSA DGO group (39.5 +/- 14.7 silver grains/cell for normal gingiva vs. 255.3 +/- 77.1 silver grains/cell for CSA DGO samples; P < 0.001). The presence of PDGF-B in these cells was confirmed in all cases by immunocytochemical localization. Additionally, PDGF-B producing cells were identified as macrophages in sections taken from an additional patient with CSA DGO by double immunofluorescence labeling of the CD51 membrane marker for macrophages and intracellular PDGF-B. These findings are consistent with the concept that healthy gingiva is in a continuous state of wound repair and support the hypothesis that CSA DGO is associated with enhanced macrophage PDGF-B gene expression rather than an increase in the number of PDGF-B producing macrophages.

Antigens, CD↗
PubMed1996

Cyclosporine A upregulates platelet-derived growth factor B chain in hyperplastic human gingiva.

Cyclosporine A (CSA) is a widely used immunosuppressant for transplant patients and is also used for the treatment of a wide variety of systemic diseases with immunologic components. A prominent side effect of CSA administration is gingival overgrowth (hyperplasia). It has been postulated that CSA alters fibroblast activity through effects on various growth factors/cytokines. However, as yet, data concerning the molecular mechanisms involved in pathologic connective tissue proliferation are preliminary in nature. Our previous investigations concerning phenytoin-induced effects on platelet-derived growth factor B (PDGF-B) gene expression have demonstrated that other drugs which cause gingival overgrowth can upregulate macrophage PDGF-B gene expression in vitro and in vivo. The purpose of the present study was to evaluate PDGF-B gene expression in gingival tissues of patients receiving CSA therapy and exhibiting gingival overgrowth to determine if similar PDGF-B upregulation occurs in response to CSA and to identify PDGF-B producing cells in these tissues. Quantitative competitive reverse transcription polymerase chain reaction (QC-RTPCR) techniques were utilized to measure PDGF-B mRNA levels in CSA overgrowth patients and normal controls (N = 6/group). Results were expressed as mean +/- mRNA copy number and tested for significance using unpaired t-tests. Gingival samples were harvested (standardized for local inflammation at the sample site), total RNA was extracted, and QC-RTPCR was performed using specific PDGF-B primers and a corresponding competitive internal standard. CSA-treated patients exhibiting gingival overgrowth demonstrated approximately 48-fold increase in PDGF-B mRNA (7667.1 +/- 477.4 copies for CSA patients vs. 158.2 +/- 37.1 copies for controls; P < 0.001). Additionally, dual fluorescence immunohistochemistry for mature macrophage marker antigen (CD51) and intracellular PDGF-B was utilized to identify and localize PDGF-B producing cells were demonstrated to be macrophages distributed in a non-uniform manner throughout the papillary connective tissue. These results further support the hypothesis that the molecular mechanisms responsible for drug-induced gingival overgrowth may involve upregulation of PDGF-B macrophage gene expression. We continue to investigated specific CSA-induced alterations of macrophage PDGF-B gene expression in vitro and in vivo.

Adult↗
PubMed1995

Platelet-derived growth factor levels in wounds of diabetic rats.

Delayed wound healing is a troublesome complication of Diabetes. Results from recent investigations concerning the potential cellular and molecular mechanisms responsible for diabetic wound healing deficiency are preliminary in nature. Some studies have demonstrated that direct application of certain growth factors/cytokines can facilitate wound healing in diabetic models. It is possible that refractory diabetic wounds are the result of deficiencies in growth factors/cytokines important for the normal wound healing process. Platelet-Derived Growth Factor (PDGF) levels were examined by radioimmunoassay in wound tissue of normal and diabetic rats (streptozotocin-induced diabetes). Immunohistochemical analysis was utilized to localize and characterize PDGF immunopositive cells at the wound site of normal and diabetic animals. At the wound site, normal animals demonstrated significantly elevated PDGF levels compared to diabetic animals at 5 days post-wounding (no differences were observed in the spleen or contralateral control tissue). There appeared to be a visible increase in PDGF immunopositive cells at the wound site in both experimental and control groups. By day 10 post-wounding, PDGF levels at the wound site in normal animals were reduced becoming similar to PDGF levels in diabetic animals. This corresponded to an apparent reduction of PDGF immunopositive cells in both groups (similar to baseline levels). PDGF levels in both groups remained stable until day 20 post-wounding when a significant elevation of wound site PDGF levels occurred in the diabetic group. The findings suggest that absence of an initial increase in PDGF may play an important role in poor wound healing observed in diabetic animals. The reduction in PDGF may be related to decreased cellular PDGF production rather than a lack of PDGF-producing cells. Perhaps the diabetic state inhibits cellular PDGF gene expression signaled by wounding or interferes with normal PDGF expression at the wound site.

Animals↗
PubMed1995

Quantitative measurement of neuronal calbindin-D28k by radioimmunocytochemistry.

The calcium-binding protein calbindin-D28k (CaBP) has been localized in high concentration in several neuronal populations within the CNS and is believed to act as an intracellular calcium buffer. There has been much interest and speculation concerning its potential neuroprotective function. A radioimmunocytochemistry (RIC) technique for the cellular quantitation of protein has been applied to quantitative measurement of neuronal CaBP in vivo and in vitro. The method permits cellular comparison of CaBP content within tissue sections or cells in culture. Through the use of specific primary antibody, 35S-labeled secondary antibody, and photographic emulsion, RIC combines the simplicity of standard immunocytochemical procedures with the sophistication and power of in situ hybridization, autoradiography, and image analysis. CaBP levels are expressed as mean +/- S.E.M. silver grains/cell. CaBP content has been measured and compared in mouse cerebellar Purkinje cells (56.5 +/- 6.9 grains/cell), granule cells of the hippocampal dentate gyrus (10.3 +/- 2.1 grains/cell), midline ventral tegmental neurons (11.6 +/- 2.9 grains/cell), and human SH-SY-5Y neuroblastoma cells in culture (5.1 +/- 0.9 grains/cell). As measured by RIC, mouse cerebellar Purkinje cells contain approximately 5-fold more CaBP than granule cells of the hippocampal dentate gyrus/midline ventral tegmental neurons and 10-fold more CaBP than cultured human SH-SY-5Y neuroblastoma cells. Assay reproducibility was demonstrated by comparison of adjacent sections which yielded a 3-9% intra-assay variability. Results were validated and confirmed by comparison to previous radioimmunoassay studies which indicated similar ratios of CaBP levels between brain regions/cell types.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗