Case based learning: a method for better understanding of biochemistry in medical students.

INTRODUCTION: Health professionals need to develop analytic and diagnostic thinking skills and not just a mere accumulation of large amount of facts. Hence, Case Based Learning (CBL) has been used in the medical curriculum for this reason, so that the students are exposed to the real medical problems, which helps them in develop analysing abilities. This also helps them in interpreting and solving the problems and in the course of doing this, they develop interest. In addition to didactic lectures, CBL was used as a learning method. METHODS: This study was conducted in the Department of Biochemistry, S.B.K.S.M.I and R.C, Sumandeep Vidyapeeth ,Piparia, Gujarat, India. A group of 100 students were selected and they were divided into two groups as the control group and the study group. A total of 50 students were introduced to case based learning, which formed the study group and 50 students who attended didactic lectures formed the control group. RESULTS: A very significant improvement (p<0.0001) was observed among the students after the CBL sessions and they were also motivated by these sessions. A 4 point Likert scale questionnaire which contained 8 questions was administered to the students, to know their perception on the usefulness of the CBL. 98% of the students reported that they found the CBL sessions to be an interesting method of gaining knowledge. 84% of them felt that they exposed them to an experience of logical application of the knowledge which was gained in cracking cases, which would be of great help in the future also. CONCLUSION: Case Based Learning (CBL) was used and it is effective in the medical curriculum for a better understanding of Biochemistry among the medical students.

Natalizumab (Tysabri).

Natalizumab is a humanized IgG4κ monoclonal antibody that is a selective adhesion molecule inhibitor, which prevents adhesion of leukocytes to endothelial cells. It is the first monoclonal antibody approved by the FDA for the treatment of relapsing-remitting MS. This article will review the mechanism of action and clinical role of this agent.

Rituximab (Rituxan).

Rituximab is a monoclonal antibody that was first approved by the FDA as an antineoplastic agent designed to treat B-cell malignancies. This article will review the mechanism of action and clinical role of this anti-B-cell agent.

Spontaneous intracranial hypotension causing reversible frontotemporal dementia.

Spontaneous intracranial hypotension (SIH) causes postural headache and neurologic symptoms owing to traction and brain compression. A 66-year-old man with chronic headache and progressive personality and behavioral changes typical of frontotemporal dementia was examined. He had MRI findings of SIH with low CSF pressure. His headache, dementia, and imaging abnormalities abated after treatment with prednisone. SIH can cause reversible frontotemporal dementia, and should be considered when dementia and behavioral changes are accompanied by headache.

Calcitonin is expressed in gonadotropes of the anterior pituitary gland: its possible role in paracrine regulation of lactotrope function.

Previous studies from this laboratory have shown that salmon (S) calcitonin (CT)-like immunoreactive peptide (CTI) is synthesized and secreted by the anterior pituitary (AP) gland. These studies also co-localized CTI to gonadotropes, and demonstrated that SCT is a potent inhibitor of lactotrope function. However, the molecular structure of putative gonadotrope-derived CTI that inhibits lactotrope function has not been defined. The present studies cloned CT cDNA (pit-CT cDNA) from a mouse gonadotrope L beta T2 cell line using RT-PCR and rapid amplification of cDNA ends (RACE) techniques. Alignment of nucleotide sequences of pit-CT and mouse CT revealed greater than 99% homology between the sequences. The pit-CT cDNA was ligated into a mammalian expression vector, and the construct was transfected into L beta T2 cells. Two stable transfectant cell lines (CT.U6/A and B) were obtained by selection in G418. Subsequent S1-nuclease protection assay and immunocytochemistry results have shown that: (1) pit-CT peptide expressed by CT.U6 cell lines immunoreacted with GCT1-anti-SCT serum; (2) secretions of CT.U6 cells inhibited prolactin (PRL) release, PRL mRNA abundance and DNA synthesis of PRL-secreting GGH3 cells; and (3) CT.U6-induced inhibition was abolished by GCT1-anti-SCT serum. The studies also generated a riboprobe from the cloned pit-CT cDNA, and localized CT mRNA expression in gonadotropes of rat AP gland by in situ hybridization histochemistry. These results demonstrate that pit-CT mRNA is closely homologous to mouse CT mRNA; it is expressed by gonadotropes of the rat AP gland, and the peptide may significantly affect lactotrope function by inhibiting PRL release and cell proliferation.

Role of stimulatory guanine nucleotide binding protein (GSalpha) in proliferation of PC-3M prostate cancer cells.

Previous studies have shown that calcitonin-like immunoreactive substances are secreted by primary prostate cells. Furthermore, exogenously added calcitonin stimulates proliferation of androgen-responsive LnCaP cells. To examine the possible effect of calcitonin on growth of invasive prostate cancer cells, we tested its effects on proliferation of PC-3M cells. Calcitonin stimulated DNA synthesis of PC-3M cells in a dose-dependent fashion, and also stimulated adenylyl cyclase and protein kinase C activities. To further delineate the role of these signaling cascades in proliferation of PC-3M prostate cancer cells, we selectively activated these pathways by transfecting cDNAs expressing constitutively active forms of either Gsalpha (Gsalpha-QL) or Gqalpha (Gqalpha-QL). cDNAs expressing wild-type forms of G-proteins (Gsalpha-WT and Gqalpha-WT) were used as vehicle controls. Gqalpha-QL transfectants exhibited growth inhibition and terminal differentiation. Those expressing Gsalpha-QL exhibited a dramatic increase in growth rate. Gsalpha-QL transfectants displayed an almost 3-fold increase in [3H]-thymidine incorporation and over a 4-fold increase in growth rate when compared with parental PC-3M cells or those expressing wild-type Gsalpha (Gsalpha-WT). The growth-promoting action of Gsalpha-QL could not be mimicked by either 8-bromo cAMP or forskolin. However, nifedipine, a calcium channel antagonist, potently and selectively inhibited DNA synthesis in Gsalpha-QL transfectants. These results suggest that the growth-promoting actions of Gsalpha on PC-3M cells may be mediated by nifedipine-sensitive proliferative events.

Central nervous system tuberculosis: imaging manifestations.

Tuberculosis of the brain is a disease of pathologic complexity and clinical subtlety-characteristics that manifest in the radiologic presentation of the disease and may make the task of interpreting radiologic data difficult. Much of the difficulty, however, reflects differences between the pathologic processes of tuberculosis and other infective diseases of the brain, and once these differences are appreciated, interpreting radiologic images becomes clearer.

Calcitonin inhibits anterior pituitary cell proliferation in the adult female rats.

Previous studies have shown that CT-like immunoreactive peptide(s) (pit-CT) is synthesized by the anterior pituitary (AP) gland, and exogenously added salmon(s) CT inhibits PRL release and PRL gene transcription in cultured AP cells. Anti-sCT serum, which immunoreacts with pit-CT, stimulates PRL secretion, suggesting pit-CT is a physiologically relevant PRL-inhibiting hormone. Using proliferating cell nuclear antigen (PCNA) staining and 5-bromo-2'deoxyuridine (BrdU) incorporation into newly replicated DNA, the effect of calcitonin (CT) on cellular proliferation in the rat anterior pituitary gland (AP) was examined. CT significantly attenuated PCNA-immunopositive as well as BrdU-positive AP cell populations in dispersed rat AP cells. A second series of experiments tested the effects of CT on AP cell proliferation in vivo. OVX + E2 rats were injected with 200 microg CT (iv), the rats killed at various time points, and the APs were processed for BrdU staining. CT inhibited BrdU incorporation at all time points up to 15 h after the injection, and this inhibitory effect was reversed at later time points. The effect of CT was concentration dependent, and a maximal inhibition was observed 10 h after the CT injection. Subsequent experiments identified CT-responsive AP cell populations using double immunofluorescence for BrdU and either PRL or FSH. The number of BrdU-labeled lactotropes in the AP gland declined by 74% in the CT-treated rats. Neutralization of endogenous pit-CT by passive immunization with anti-sCT serum caused a 2-fold increase in AP cell proliferation. These results suggest an important role for the endogenous pit-CT in regulation of lactotrope population of the AP gland.

3,5 cyclic adenosine monophosphate mediates the salmon calcitonin-induced increase in hypothalamic tyrosine hydroxylase activity.

This study examined the effect of salmon calcitonin (sCT) on hypothalamic tyrosine hydroxylase (TH) activity and evaluated the cellular signaling mechanisms involved in the response. Fetal hypothalamic cells were cultured in a defined medium and treated with sCT and/or specific protein kinase inhibitors on day 14 in vitro. sCT (0.1-10 nM) increased both TH activity and cellular cAMP content in a concentration-dependent manner. sCT (10 nM) increased TH activity to 150-175% of control values and resulted in a 10-fold increase in cellular cAMP content. Both the C1a and C1b CT receptor isoforms were present in the cultures, as assessed by RT-PCR. Rp-adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS), a cAMP antagonist, and H-8, a cyclic nucleotide kinase inhibitor, blocked the sCT-induced increase in TH activity, with complete abolition of the response observed at concentrations of 1 mM and 5 microM, respectively. sCT (10 nM) increased radiolabeled phosphate incorporation into TH protein to 169% of control values and 1 mM Rp-cAMPS completely blocked this effect. In contrast, neither Calphostin C, a protein kinase C inhibitor, nor U-73122, a phospholipase C inhibitor, significantly altered the ability of sCT to increase TH activity. Likewise, the sCT-induced increase in TH activity was observed after pretreating the cells with either BAPTA/AM, an intracellular calcium chelator, or thapsigargin, an inhibitor of the endoplasmic reticulum calcium pump. These data indicate that sCT has a profound stimulatory effect on TH activity in fetal hypothalamic cells and that enhanced phosphorylation of TH coincides with the sCT-induced increase in enzyme activity. Moreover, CT receptors, which are linked to cAMP production, are expressed in the hypothalamic cells and a cAMP-dependent mechanism mediates the sCT-induced activation and phosphorylation of TH.

Constitutive activation of stimulatory guanine nucleotide binding protein (G(S)alphaQL)-mediated signaling increases invasiveness and tumorigenicity of PC-3M prostate cancer cells.

An abnormal stimulation of cAMP signaling cascade has been implicated in various human carcinomas. Since the agents activating G(S)alpha-mediated signaling pathways have been shown to increase in vitro proliferation of prostate cancer cells, present studies examined the G(S)alpha-mediated signaling in tumorigenicity and invasiveness of PC-3M prostate cancer cells. PC-3M cells were stably transfected with plasmids containing either wild type (G(S)alpha-WT) or constitutively active (gsp mutant of G(S)alpha or G(S)alpha-QL) cDNAs. The stable transfectants were then tested for: (1) colony formation in soft agar; (2) cell migration and penetration of basement matrix in an in vitro invasion assay; and (3) the ability to form tumors and metastases in nude mice. PC-3M cells expressing G(S)alpha-QL protein displayed 15-fold increase in their ability to migrate and penetrate the basement membrane as compared to parental PC-3M cells or those expressing G(S)alpha-WT. G(S)alpha-QL transfectants also displayed a dramatically greater rate of growth in soft agar, and greater tumorigenicity and metastasis forming ability when orthotopically implanted in nude mice. All mice receiving PC-3M cells produced primary tumors within 5 weeks after implantation. However, the cells expressing G(S)alpha-QL displayed a significantly faster tumor growth as assessed by prostate weight (greater than 20-fold as compared to PC-3M cells), and produced metastases in kidneys, lymph nodes, blood vessels, bowel mesentery and intestine. Interestingly, expression of G(S)alpha-WT reduced the ability of PC-3M cells to form tumors in nude mice. These results suggest that persistent activation of G(S)alpha-mediated signaling cascade can dramatically accelerate tumorigenesis and metastasizing ability of prostate cancer cells.

Comparison of phased-array and body coils for MR imaging of liver.

AIMS AND OBJECTIVES: To compare liver lesion conspicuity using torso phased-array (TPA) and body coils with two pulse sequences. METHODS: Sixty patients with 125 focal hepatic lesions underwent T2-weighted fast spin-echo (T2-FSE) and fast multiplanar inversion recovery (FMPIR) imaging with a standard body coil and with a TPA coil. The first 30 patients were scanned identically in both coils with four acquisitions; the second 30 were scanned with four acquisitions in the body coil and two in the TPA coil. RESULTS: Liver-lesion contrast-to-noise (C/N) was significantly higher for the TPA coil both with four acquisitions (P< 0.001) and with two acquisitions (P < 0.002) using FMPIR, compared to with four acquisitions in the body coil. Liver-lesion C/N for T2-FSE was equivalent in both coils. Liver-lesion C/N was significantly higher (P<0.01) for FMPIR than T2-FSE both in the body coil and in the TPA coil. CONCLUSION: Liver-lesion C/N was significantly higher using the TPA coil rather than the body coil. Imaging time can be reduced by decreasing the number of acquisitions with the TPA coil.

Muscarinic cholinergic receptors promote growth of human prostate cancer cells.

BACKGROUND: Recent evidence suggests that muscarinic receptors induce mitogenesis in cells capable of undergoing cell proliferation. Human prostate gland is innervated by the autonomic nervous system and muscarinic receptors have been localized in the prostate gland. METHODS: Effects of carbachol (a stable analog of acetyl choline) on DNA synthesis of LNCaP cells (a human prostate cancer cell line) and primary prostate cells was examined. The DNA synthesis in the cultured cells was assessed using techniques of 3H-thymidine incorporation and bromodeoxyuridine (BrdU) incorporation immunocytochemistry. RESULTS: Carbachol induced a significant increase in BrdU- and 3H-thymidine incorporation of LNCaP cells. The effect of carbachol was completely reversed by atropine, a selective muscarinic antagonist. Subtypes of muscarinic receptors mediating carbachol-induced DNA synthesis were identified using selective receptor subtype antagonists. Pirenzepamine and gallamine did not affect carbachol action on LNCaP cells but diphenylpyralamine, an M3 receptor antagonist, completely blocked carbachol-induced DNA synthesis. Carbachol also stimulated DNA synthesis in primary prostate cells. Prostate carcinoma (PC)-derived primary prostate cells displayed a dramatically greater response to carbachol (a ten-fold increase in DNA synthesis) as compared to benign prostate hypertrophy (BPH)-derived cells (a two-fold increase in DNA synthesis). CONCLUSIONS: M3 receptors stimulate the proliferation of LNCaP cells, BPH-derived and PC-derived primary prostate cells. A dramatically higher response to carbachol by PC-derived prostate cells suggests that M3 receptors may be up-regulated in PC. M3 receptors may play a significant role in PC tumors growth and androgen-independent tumor progression.

Calcitonin is a physiological inhibitor of prolactin secretion in ovariectomized female rats.

Calcitonin (CT) inhibits secretion of PRL when administered intravenously in rats and humans. It also inhibits PRL release from cultured rat anterior pituitary (AP) cells. Recent evidence suggests that CT-like immunoreactive peptide is synthesized and released from the AP gland. However, its physiological role in the regulation of PRL secretion has not been understood. Present studies tested the role of endogenous pituitary CT (pit-CT) in the regulation of PRL secretion in vivo by passive immunization. In the first group of experiments, ovariectomized (ovx) adult female rats were administered either preimmune or anti-salmon CT (sCT) serum, and their serum PRL levels were analyzed at various time points up to 3 h. A second group of experiments examined the effects of anti-sCT serum and dopamine on PRL release from cultured rate AP cells. In the next group of experiments, the regional distribution of pit-CT secretion was examined in different sections of the AP gland. In the last set, CT-like activity of AP extract was tested in neonatal rat kidney cells, which respond to CT with an increase in cAMP accumulation. These experiments also tested whether anti-sCT serum reduces AP extract-induced increase in cAMP accumulation. The results suggest that anti-sCT serum dramatically increased serum PRL levels (by 5-fold) of ovx rats within 30 min of administration. The serum PRL levels declined gradually after the peak. However, a significant increase in serum PRL levels was maintained by the anti-sCT serum for the duration of the experiment. The anti-serum also induced a significant increase in PRL release from cultured AP cells when added to the presence or absence of dopamine. The distribution profile of pit-CT within the AP gland suggests that the release of pit-CT immunoreactivity was significantly greater in the inner sections, and anti-sCT serum also caused greater increase in PRL release in these sections. Finally, AP extract and sCT stimulated cAMP accumulation in neonatal rat kidney cells, and anti-sCT serum significantly reduced AP extract-induced cAMP accumulation. These results demonstrate that pit-CT is an important regulator of tonic PRL secretion in female rats and can potently inhibit PRL secretion even in the presence of dopamine.

Calcitonin-like peptide containing gonadotrophs are juxtaposed to cup-shaped lactotrophs.

Calcitonin (CT) is known to inhibit basal and TRH-stimulated prolactin release in cultured anterior pituitary cells in vitro and pituitary CT-like peptide (pit-CT) is synthesized and released by isolated anterior pituitary cells. However, the specific cell type containing pit-CT has not been identified. To determine this, double label immunohistochemistry was performed on pituitary sections from male rats using antisera for specific marker peptides of gonadotrophs, thyrotrophs, lactotrophs, somatotrophs, corticotrophs, and folliculo-stellate cells. CT was only colocalized with gonadotroph-specific markers and the distribution of pit-CT immunoreactive (IR) cells followed the patterns of gonadotroph distribution in male and female rats. Double and triple label immunohistochemistry using antiserum for CT, FSH, and PRL showed an apposition of calcitonin-like peptide containing gonadotrophs to cup-shaped lactotrophs. To examine whether pit-CT IR was altered, similarly to gonadotrophs, with known changes in PRL serum levels, studies were extended to ovariectomized, pregnant, and lactating rats. The area covered by pit-CT immunoreactivity and the tissue content of pit-CT significantly differed between physiological states and the pit-CT level was inversely related to the known PRL status. Pit-CT containing gonadotrophs were in all cases apposed to cup-shaped lactotrophs. These results provide histological support for previous studies proposing that pit-CT serves as a paracrine inhibitor of PRL release.

Pregnancy and its outcome in quadriplegia due to Pott's spine.

Pregnancy with quadriplegia is a problem sometimes encountered in obstetric practice. The etiology of quadriplegia in the developed world is mainly spinal cord tumor or accident, while in the developing countries the main cause is tuberculosis of the spine. We report the management of two pregnant patients with quadriplegia due to tuberculosis of the cervical spine. Worsening of the neurological condition necessitated early surgical intervention, and termination of pregnancy was advised in both patients. Literature on the subject makes frequent reference to the life-threatening complication of autonomic hyperreflexia encountered during pregnancy and delivery. It is characterized by sweating, headache, severe hypertension leading to unconsciousness and convulsions. These complications, surprisingly, were absent in both of our patients.

Aneurysmal bone cyst of the temporal bone: MR findings.

MR findings in a case of aneurysmal bone cyst of the temporal bone are described. MR can suggest the diagnosis of aneurysmal bone cyst and also give ancillary information that is helpful for surgical treatment.

Calcitonin inhibits prolactin gene transcription in rat pituitary cells.

Our recent studies have shown that calcitonin (CT)-like immunoreactive peptide is synthesized and released from cultured rat anterior pituitary (AP) cells, and may serve as a paracrine inhibitor of PRL release. The present studies investigated effects of CT on basal and TRH-induced PRL mRNA levels in rat AP and rat pituitary tumor GH(3) cells. CT attenuated steady-state PRL mRNA levels in a dose-dependent fashion in primary rat AP and GH(3) cells. The kinetics of CT action suggests that 100NM: CT caused a significant decline after 3 h, and the inhibition was sustained at least until the longest tested incubation period of 30 h. Results from nuclear run-on assays suggest that 100 nM CT decreased the rate of PRL gene transcription by 80% after 30 min of incubation. CT did not affect PRL mRNA levels in Ca(2+)-depleted GH(3) cells but dramatically decreased them in Ca(2+)-repleted cells. Bay K 8644 induced increase in PRL mRNA levels of Ca(2+)-repleted GH(3) cells and CT did not affect this increase. These results suggest that CT rapidly and selectively inhibits PRL gene transcription in primary AP and GH(3) cells, and support a possibility that CT-induced attenuation of PRL mRNA may involve cytoplasmic Ca(2+).

Estrogen attenuates expression of calcitonin-like immunoreactivity in the anterior pituitary gland.

Estrogens increase prolactin (PRL) synthesis and release in rats and humans, whereas pituitary-derived calcitonin-like immunoreactive peptide (pit-CT) inhibits PRL gene expression and release. To test the hypothesis that estrogens stimulate lactotrophs by diminishing pit-CT expression, the present studies examined effects of ovariectomy (ovx) and estradiol (E2) administration on (1) pit-CT IR cell population; (2) pit-CT IR content and (3) release of pit-CT IR by cultured anterior pituitary (AP) cells. Ability of anti-calcitonin immunoglobulins (anti-CT IgG) to stimulate PRL release from cultured AP cells was also examined. The results suggest that ovariectomy induced a large increase in pit-CT IR cell population in the AP gland and E2-treatment dramatically reversed this increase. Similar changes were observed in pit-CT IR content of AP extracts. Cultured AP cells from ovx rats released significantly higher amounts of pit-CT IR, and anti-CT IgG induced a significant increase in basal PRL release. AP cells from E2-treated rats secreted lower amounts of pit-CT IR and this was associated with significantly higher PRL release. These results suggest that estrogens may stimulate lactotrophs, at least in part, by removing inhibitory influence of endogenous pit-CT.

Calcitonin stimulates growth of human prostate cancer cells through receptor-mediated increase in cyclic adenosine 3',5'-monophosphates and cytoplasmic Ca2+ transients.

Our recent study has shown that a calcitonin (CT)-like immunoreactive substance(s) is secreted by cultured prostate cells, and secretion of this material is significantly higher in malignant than in benign prostate cells. To test the hypothesis that prostatic CT may serve as a paracrine/neuroendocrine factor, the present study investigated for the presence of CT receptors in the prostate gland. Signal transduction mechanisms activated by CT were examined, and the study also tested its effects on prostate cell proliferation, as assessed by [3H]thymidine incorporation. The results show that high affinity binding sites for [125I]salmon CT were present in plasma membrane fractions of human prostate tissue specimens and the prostate cancer LnCaP cell line. The maximal binding for CT receptors was 564 +/- 163 fmol/mg protein, and the apparent dissociation constant (Kd) was 2.89 +/- 0.58 nM. CT induced a dose-dependent increase in cAMP generation in LnCaP cells. The effect of CT on cytoplasmic Ca2+ transients of LnCaP cells was examined by videofluoromicroscopy. CT (100 nM) induced a rapid and sharp increase in cytoplasmic Ca2+ concentrations in LnCaP cells. The CT-induced increase in cytoplasmic Ca2+ transients appeared to be biphasic (spike and plateau), and this increase was 4- to 10-fold during the initial phase. The profile of this response is characteristic of the activated Ca2+/phospholipid second messenger system. CT also caused a dose-dependent increase in [3H]thymidine incorporation by LnCaP cells. These results suggest that a locally secreted CT-like peptide(s) induces mitogenic responses in prostate cancer cells. This action seems to be mediated through activation of signaling mechanisms, leading to the accumulation of two different second messengers, cAMP and calcium. Activation of dual second messenger systems by CT receptors suggests that the peptide hormone may play an important role in rapidly growing cell populations during the process of tumor formation.