Unveiling the anti-echinococcal efficacy of amide-based compounds: An in-silico and in-vitro study.

Cystic echinococcosis (CE) is a significant global public health concern, particularly in regions where livestock rearing is prevalent. Despite its impact on morbidity and mortality, CE has received insufficient attention compared to other neglected tropical diseases. The complexities in CE management arise from challenges in early detection, effective treatment, and parasite eradication. The present study addresses this gap by exploring innovative therapeutic approaches using amide-based compounds. In recent years, computational approaches and in-vitro studies have become prominent in neglected tropical disease drug discovery. Leveraging insights from previous studies on amide-based compounds with anti-parasitic potential, this study systematically designed, synthesized, and characterized a library of 30 amide compounds. The research integrated in-silico screening, molecular docking, and in-vitro experimentation to assess the anti-echinococcal potential of these compounds. The study identified five promising amide compounds, namely 3,5-dinitro-N-p-tolylbenzamide, N-p-tolyl-1-naphthamide, N-p-tolyl-4-(trifluoromethoxy)benzamide, 4-pentyl-N-p-tolylbenzamide, and 2,3,4,5,6-pentafluoro-N-p-tolylbenzamide, based on their docking scores. These compounds were synthesized and characterized through various spectroscopic techniques, confirming their structural integrity. The in-vitro cytotoxicity assay on HepG2 cell lines revealed varying degrees of cytotoxicity for the synthesized compounds. Notably, 4-pentyl-N-p-tolylbenzamide demonstrated the least cytotoxicity. Subsequent scolicidal activity assessments on E. granulosus protoscoleces demonstrated the potent protoscolicidal activity of N-p-tolyl-1-naphthamide, indicating its potential as an effective anti-echinococcal agent. Overall, this study presents a comprehensive exploration of amide-based compounds as potential therapeutic agents against CE. The findings contribute to the development of innovative strategies for CE treatment, addressing the urgent need for effective and safe drugs in managing this neglected tropical disease.

Vacuum-Assisted Closure Therapy: A Lifesaver in a Case of Neck Necrotizing Fasciitis.

Necrotizing fasciitis (NF) is a severe and rare soft tissue infection with a high potential for mortality, particularly in cases related to odontogenic infections in immunocompromised patients. The conventional treatment for NF includes broad-spectrum antibiotics and aggressive surgical debridement. This report presents a unique case of a 34-year-old healthy male who developed NF following a lower left wisdom tooth extraction. The infection extended into the superior mediastinum, requiring emergency surgical intervention. The therapeutic management included vacuum-assisted closure (VAC), a treatment modality showing promise in managing complex soft tissue infections, in combination with other adjunct treatments. The patient showed a satisfactory healing process and no signs of recurrence during the six-month follow-up period. This case underlines the importance of early diagnosis and the potential benefit of VAC therapy in managing advanced NF, emphasizing the need for further research and clinical application.

Mammary analogue secretory carcinoma presenting with cervical lymphadenopathy: A rare case report with review of the literature.

INTRODUCTION: Mammary analogue secretory carcinoma is a rare malignant tumor of the salivary glands that typically involves the major glands. The aim of the current study is to report a rare case of mammary analogue secretory carcinoma that presented with left cervical lymphadenopathy. CASE REPORT: A 59-year-old lady presented with left cervical lymphadenopathy. Tissue biopsy and immunohistochemistry revealed metastatic carcinoma, favoring ovarian origin. Staging workup was performed and, ultimately, the patient was treated as having a carcinoma of unknown primary. After showing partial response to therapy, left side neck dissection was performed. Based on better assessment of the histologic picture and a broader panel of immunohistochemistry performed on the excision specimen, the final diagnosis was that of mammary analogue secretory carcinoma. DISCUSSION: Mammary analogue secretory carcinoma is usually an indolent salivary gland carcinoma, with the majority of patients presenting with a slow-growing, painless mass measuring approximately 2 cm in size, and a reported duration ranging from 2 months to several years. In certain cases, pain and facial paralysis have been reported. It could also be found incidentally during radiologic assessment for thyroid illness or routine dental screening. CONCLUSION: Diagnosing mammary analogue secretory carcinoma is challenging, and this should be in the differential diagnosis list of metastatic carcinomas to cervical lymph nodes.

Cancer Incidence in the Kurdistan Region of Iraq: Results of a Seven-Year Cancer Registration in Erbil and Duhok Governorates.

INTRODUCTION: There are limited published data regarding the recent incidence trends of cancer in Iraqi Kurdistan. METHODS: The present study assessed the epidemiological estimates of cancer incidence, as well providing a projection of future cancer trends in the upcoming decade by analysing the population-based cancer registry between 2013 and 2019, in both the Erbil and Duhok governorates. A retrospective analysis was performed on data retrieved from the Medical Statistics Department at the Ministry of Health, Kurdistan Regional Government (KRG). RESULTS: The total number of female cancer patients was higher in both governorates, and the total incidence of patients with cancer increased by over 2x between 2013 and 2019 in Erbil and Duhok, from 73 to 174 patients/100,000 individuals for women, and 36 to 85 patients/100,000 individuals for men. Analysis indicated that the percentage of patients with cancer is projected to increase by >2x in the current decade, from 3,457 cases to 4,547 and 4,449 cases in the Erbil governorate; and from 1,365 to 2,633 and 2,737 cases in 2028 based on LSTM and bi-LTSM analysis in the Duhok governorate. Lung cancer (LC) and female breast cancer (BC) were the most prominent types of cancers diagnosed since 2013 in both the Erbil and Duhok governorates. CONCLUSION: The striking pattern of trends for both present and future cancer incidence rates require urgent solutions and comprehensive efforts to control risk factors that promote the increasing incidence of cancer in these two KRG governorates.
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Assessing the readiness of hospitals in Riyadh Province for efficient and timely stroke management: A pilot study.

OBJECTIVES: To assess the readiness of hospitals in Riyadh to establish acute stroke centers by following the Australian Clinical Guidelines for Stroke Management. METHODS: This study was a quantitative cross-sectional observational study conducted among hospitals in the central region of Saudi Arabia (Jan 2018 - April 2018). A self-administered questionnaire/survey tool was adapted from an Australian survey developed by the Stroke Foundation in Melbourne, Australia.The data were analyzed using SPSS version 21.0. Appropriate statistical tests (chi-square and Fisher's exact test) were used for bivariate analyses. RESULTS: A total of 3932 stroke patient visits were recorded in 37 hospitals in the central region of Saudi Arabia. The most common limitations of acute stroke services were that 25 (67.57%) of the hospitals had no stroke unit and 21 (56.76%) had inadequate clinical staff. Magnetic resonance imaging and computed tomography were available in 32 (86.49%) and 36 (97.30%) hospitals, respectively. Only two-thirds of hospitals 25 (67.57%) followed protocols for rapid Emergency Department (ED) triage. CONCLUSION: We found that most of our hospitals were not fully prepared to address acute stroke management in a manner that was reasonably consistent with international guidelines. We recommend raising the hospital's requirements a higher level to be in line with the stroke guidelines.

Regional functional and structural abnormalities within the aorta as a potential driver of vascular disease in metabolic syndrome.

NEW FINDINGS: What is the central question of this study? Is aortic dysfunction, a significant contributor to cardiovascular disease in metabolic syndrome, expressed uniformly across both the thoracic and abdominal aorta? What is the main finding and its importance? Our study shows that, in the setting of metabolic syndrome, functional and structural deficits in the aorta are differentially expressed along its length, with the abdominal portion displaying more extensive vascular abnormalities. It is, therefore, likely that early interventional strategies targeting the abdominal aorta might alleviate cardiovascular pathologies driven by the metabolic syndrome. ABSTRACT: The extent of vascular dysfunction associated with metabolic syndrome might vary along the length of the aorta. In this study, we investigated regional functional and structural changes in the thoracic and abdominal aorta of a rat model of metabolic syndrome, namely, high-fat diet (HFD) streptozotocin-induced diabetes mellitus (HFD-D). Four-week-old male Wistar albino rats were fed with either HFD or control diet (CD) for 10 weeks. At week 6, 40 mg/kg streptozotocin and its vehicle were injected i.p. into HFD and CD groups, respectively. At the end of the feeding period, rats were euthanised and aortic segments collected for assessment of vascular functional responses and histomorphometry. Tail-cuff systolic blood pressures (154 ± 6  vs. 110 ± 4 mmHg) and areas under the curve for oral glucose and i.p. insulin tolerance tests were greater in HFD-D versus CD rats. Abdominal aortic vasoconstriction in response to noradrenaline and KCl was greater in HFD-D compared with CD rats. Thoracic vasoconstrictor responses to noradrenaline, but not KCl, were greater in the HFD-D group. Abdominal, but not thoracic, endothelium-dependent vasorelaxation in response to acetylcholine was blunted in HFD-D relative to CD rats; however, nitric oxide-dependent vasorelaxation in HFD-D rats was impaired in both thoracic and abdominal segments. The abdominal aorta of HFD-D rats showed deranged interlamellar spacing and increased lipid plaque deposition. In conclusion, vascular dysfunction in metabolic syndrome is expressed differentially along the length of the aorta, with the abdominal aorta exhibiting increased susceptibility to vasoconstrictors and greater deficits in endothelium-dependent relaxation. These vascular functional abnormalities could potentially underlie the development of hypertensive cardiovascular disease associated with the metabolic syndrome.

Incorporation of graphene oxide in polyethersulfone mixed matrix membranes to enhance hemodialysis membrane performance.

Graphene is a carbon allotrope and possesses numerous unique properties which make it an attractive material in many areas. In this work, graphene oxide (GO) was added to polyethersulfone (PES) mixed matrix membranes (MMMs) to improve the performance of hemodialysis membranes. GO was synthesized from tartaric acid by pyrolysis with various temperatures of the pyrolysis and the membrane was fabricated by a casting solution method followed by its characterization. The MMMs showed better mechanical properties than pristine PES with a tensile stress and tensile strain value of 5.55 MPa and 0.039 m, respectively. The hydrophilicity of the membranes which is in agreement with contact angle values showed that GO addition increased the hydrophilicity of the MMMs. Hence, the solute flux and clearance of creatinine gave values of 2.94 L m-2 h-1 and 78.3%, respectively. Cross sectional images and the surface morphology were also recorded using scanning electron microscopy (SEM). The resulting data proved that the modified MMMs can be a potential material for hemodialysis.

Tolerability of propofol in Wada testing.

OBJECTIVE: To assess the tolerability of propofol (PF) in Wada test in an Arab population with temporal lobe epilepsy (TLE). METHODS: This observational study with consecutive sampling took place in King Fahad Medical City, Riyadh, Saudi Arabia. Nine consecutive patients with mean (± SD) age of 26 (± 5.8) years, 6 males and 3 females, underwent Wada test between January 2009 and December 2012. Six of them had left TLE, and 3 had right TLE. Each patient received 10 mg of PF in the internal carotid artery (ICA). Right hemispheric injection was followed by left hemisphere injection after 30 minutes. During the procedure, EEG monitoring showed changes within 5-18 seconds of injection as hemispheric delta slowing. Neuropsychological tests were carried out for localization of memory and language. RESULTS: We were able to lateralize speech dominance in 8 patients and memory dominance in 6 patients. Peri-procedural complications included transient euphoria (n=1), transient spasm of ICA (n=1), eye pain (n=1), facial pain (n=1), and generalized tremulousness (n=2). None of the patients exhibited a symptomatic drop in blood pressure. CONCLUSION: We found that PF is well tolerable for the Wada test, with minimally significant complications, although blood pressure should be closely monitored.

Coronary artery bypass grafting: 30-day operative morbidity analysis in 1046 patients.

BACKGROUND: To determine the rate and risk factors of three operative complications (renal failure, pneumonia, and sternal wound infection) within 30 days after isolated coronary artery bypass surgery. METHODS: Medical records of 1,046 consecutive patients between the years 2005 and 2009 were reviewed. Demographic data and peri-operative information were collected and analyzed. Univariate and multivariate analysis between different variables were performed. RESULTS: Of all patients 3.6% developed pneumonia, 5.9% developed acute renal failure and 8.5% developed sternal wound infection. Independent predictors of acute renal failure were age > 65 years (P = 0.030), pre-operative renal impairment (P < 0.005), peripheral vascular disease (P = 0.005), emergency surgery (P = 0.043), blood transfusion (P = 0.002) mechanical ventilation > 12 hours (P < 0.005) and prolonged inotropic support (P = 0.035). Pneumonia independent predictors were female gender (P < 0.005), diabetes mellitus (P = 0.024), peripheral vascular disease (P = 0.012), emergency surgery (P = 0.007), blood transfusion (P = 0.001), mechanical ventilation > 12 hours (P = 0.005) and prolonged inotropic support (P < 0.005). Sternal wound infection independent predictors were diabetes mellitus (P = 0.017), intra- and post-operative blood transfusion (P < 0.005), and prolonged inotropic support (P = 0.006). CONCLUSION: Age, female gender, history of diabetes mellitus, chronic obstructive pulmonary disease, peripheral vascular disease, renal impairment, emergency surgery, per-operative blood transfusion, mechanical ventilation > 12 hours and prolonged inotropic support are associated with the 30-day complication after on-pump isolated coronary artery bypass grafting surgery.

Intracranial angioplasty and stent placement after stenting and aggressive medical management for preventing recurrent stroke in intracranial stenosis (SAMMPRIS) trial: present state and future considerations.

OBJECTIVE: The results of prematurely terminated stenting and aggressive medical management for preventing recurrent stroke in intracranial stenosis (SAMMPRIS) due to excessively high rate of stroke and death in patients randomized to intracranial stent placement is expected to affect the practice of endovascular therapy for intracranial atherosclerotic disease. The purpose of this report is to review the components of the designs and methods SAMMPRIS trial and to describe the influence of those components on the interpretation of trial results. METHODS: A critical review of the patient population included in SAMMPRIS is conducted with emphasis on "generalizability of results" and "bias due to cherry picking phenomenon." The technical aspects of endovascular treatment protocol consisting of intracranial angioplasty and stent placement using the Gateway balloon and Wingspan self-expanding nitinol stent and credentialing criteria of trial interventionalists are reviewed. The influence of each component is estimated based on previous literature including multicenter clinical trials reporting on intracranial angioplasty and stent placement. RESULTS: The inclusion criteria used in the trial ensured that patients with adverse clinical or angiographic characteristics were excluded. Self-expanding stent as the sole stent, technique of prestent angioplasty, periprocedural antiplatelet treatment, and intraprocedural anticoagulation are unlikely to adversely influence the results of intracranial stent placement. A more permissive policy toward primary angioplasty as an acceptable treatment option may have reduced the overall periprocedural complication rates by providing a safer option in technically challenging lesions. The expected impact of a more rigorous credentialing process on periprocedural stroke and/or death rate following intracranial stent placement in SAMMPRIS such as the one used in carotid revascularization endarterectomy versus stenting trial remains unknown. CONCLUSION: The need for developing new and effective treatments for patients with symptomatic intracranial stenosis cannot be undermined. The data support modification but not discontinuation of our approach to intracranial angioplasty and/or stent placement for intracranial stenosis. There are potential patients in whom angioplasty and/or stent placement might be the best approach, and a new trial with appropriate modifications in patient selection and design may be warranted.

Proteasome Inhibitor Reduces Astrocytic iNOS Expression and Functional Deficit after Experimental Intracerebral Hemorrhage in Rats.

Intracerebral hemorrhage (ICH) is associated with perihematoma inflammation and edema. We have recently shown cell death and a robust activation of the proinflammatory transcription factor, nuclear factor-κB (NF-κB) in brain areas adjacent to the hematoma. Proteasome represents a key component necessary for the activation of NF-κB. The aim of our present study was to examine if selective proteasome inhibition with a clinically relevant agent, PS-519, might influence the ICH pathogenesis, and improve functional outcome. ICH was induced in Sprague-Dawley rats by the double blood injection method. PS-519 was administered intravenously 4 h and 15 min after induction of ICH. Behavioral testing was performed 3, 5, and 7 days later. The animals were sacrificed on day 7, and their brains were evaluated for hemorrhage size and inflammation using immunohistochemistry with antibody to various inflammatory markers. Treatment with PS-519 significantly (p < 0.05) reduced behavioral impairment post-ICH as determined by the footfault test. This effect was not due to difference in ICH volume. The improved functional status of PS-519 treated animals correlated positively (p < 0.01) with reduced expression of astroglial iNOS in areas adjacent to the hemorrhage 7 days post-ICH. No delayed changes in expression of OX-42 and ED-1 (microglia/macrophages marker), or vimentin (intermediate filament; marker of astroglia activation) were detected in animals treated with PS-519. This data suggests that modulation of proteasome-activated processes may represent a strategic target for treatment of ICH in humans.

Primary Sjogren's syndrome with central nervous system involvement.

OBJECTIVE: To describe the clinical, laboratory, and radiological features of Primary Sjogren's syndrome (PSS) with central nervous system (CNS) involvement. METHODS: A retrospective case series of 12 female patients with PSS and CNS involvement at King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia from 1991-2009. The diagnosis of PSS is defined by the American-European Diagnostic Criteria. We analyzed the clinical, radiological, and immunological features. RESULTS: The mean age was 40 years (range 16-58 years); all patient were females and presented with active neurological symptoms. The neurological involvement preceded the classic sicca symptoms (33%). Eight patients (66%) presented with myelopathy, 9 patients (75%) had optic neuritis, and the rest had variable neurological signs. Immunological tests (anti-Sjogren's syndrome A and anti-Sjogren's syndrome B) were high in 7 patients (58%). Minor salivary gland biopsy revealed inflammatory cell infiltrate in 11 patients (92%). Brain MRI showed scattered white matter changes in 7 patients (58%). Spine MRI showed multiple foci of hyperintensity in T2-weighted image in 6 patients (50%), and long segment of hyperintensity at the cervical spinal cord in 2 patients (16%). CONCLUSION: Our findings demonstrate that CNS involvements in PSS have great clinical variability and could precede the classic sicca symptoms by years. Primary Sjogren's syndrome can mimic multiple sclerosis (primary progressive multiple sclerosis or relapsing remitting multiple sclerosis), therefore a screening test for PSS should be considered in suspected cases. A well-defined management protocol awaits studies with larger case numbers.

Cerebral venous thrombosis in Saudi Arabia. Clinical variables, response to treatment, and outcome.

OBJECTIVE: To investigate cerebral venous thrombosis (CVT) clinical presentations, risk factors, and response to treatment in Saudi Arabia. METHODS: Retrospective analysis of the King Fahad Medical City, Riyadh, acute stroke database from April 2005 through February 2008 revealed 22 patients with CVT. Hypercoagulable work-up and neuroimaging were performed. RESULTS: Sixteen patients were female (72.7%), and the median age was 35 years. Clinical presentations included: headache (77.3%), seizures (54.5%), focal neurological signs (54.5%), and decreased level of consciousness (50%). Over two-thirds (n=11; 69%) of female patients had a history of oral contraceptive use, which was the most common risk factor. Protein S deficiency (n=3), antiphospholipid antibody syndrome secondary to systemic lupus erythematosus (SLE) (n=1), rhinocerebral mucormycosis (n=1), leukemia (n=1), non-Hodgkin`s lymphoma (n=1), sepsis (n=1), and unknown (n=6) were causes. Affected areas included superior sagittal (n=13), transverse (n=16), sigmoid (n=14), straight (n=6), and cavernous sinus (n=1); internal cerebral vein (n=2); vein of Galen (n=3); cortical veins (n=10); and internal jugular vein (n=12). Two patients had quadriparesis, and 2 patients died. The remainder (n=18, 81.8%) improved. Bilateral hemorrhagic presentation or venous infarction, deep venous system thrombosis, and underlying malignancy had less favorable results. CONCLUSION: Presentations in our series were similar to those in other reports, although altered consciousness and seizures were more common. Cortical vein involvement was also higher than commonly reported. Oral contraceptive use was a primary risk factor in female patients. Outcomes were favorable in 81.8% of patients.

The synthesis of hydroxyapatite through the precipitation method.

Hydroxyapatite (HA) has been earmarked as suitable for implantation within the human of its chemical makeup to human bone. In this paper, HA powders were synthesized via the precipitation method where phosphoric acid (H3PO4) was titrated into calcium hydroxide solution [Ca(OH)2]. Two parameters such as temperature and stirring rate were identified as factors that influenced the amount and purity of HA powder. Phase identification of the synthesized powder was done using X-Ray Diffraction (XRD). The results show that HA phase can be synthesized from this titration process of Ca(OH)2 and H3PO4 with yield amount of HA powder around 45 - 61 grams but with less than hundred percent purity. In order to study the effect of heat treatment to HA crystals structure, HA powder was calcined at 850 degrees C for 2 hours. It's found that the degree of crystallinity increases after calcination because of lattice expansion when the materials were heated at higher temperature

Effectiveness of surgical parathyroidectomy for secondary hyperparathyroidism in renal dialysis patients in Qatar.

Pharmacologic interventions designed to control hyperparathyroidism (HPT) in uremic patients have limitations and potentially serious adverse clinical consequences. Hence, one still has to resort to surgical parathyroidectomy (PTX) in a considerable number of dialysis patients. The aim of the present study was to illustrate our experience with 26 renal dialysis patients who underwent surgical PTX. The main indications for PTX included iPTH > 1000 pg/mL associated with severe osteitis fibrosa, debilitating pruritus, marked soft tissue calcification, or hypercalcemia with hyperphosphatemia, which sometimes complicated vitamin D therapy. All patients were resistant to more conservative measures, including control of serum phosphate, attention to oral intake and dialysate calcium levels, and oral/intravenous administration of active vitamin-D-pulse therapy. Ultrasound and technetium 99-sestamibi scan were used to image the thyroid and the parathyroid glands. Total PTX with autotransplantation was performed in 23 patients; subtotal PTX was performed in 3 patients. Histology of frozen sections taken intraoperatively showed nodular changes in 14 and diffuse hyperplasia in 12 cases. During the 2-year follow-up period significant reductions in parathyroid hormone, alkaline phospatase blood levels, skeletal changes, and soft tissue calcifications were observed. Pruritus improved in half the cases. Some improvement in hemoglobin and hematocrit was also noticed. The complication rate after PTX was low. Transient postoperative hypocalcemia requiring intensification of calcium and vitamin D therapy was seen in cases with high preoperative alkaline phosphatase levels. Recurrence was observed in two cases. Hypoparathyroidism was not recorded. We conclude that surgical reduction of parathyroid mass is a safe and effective treatment for symptomatic disease not suppressible by pharmacologic means.

A prospective, multicenter pilot study to evaluate the feasibility and safety of using the CoolGard System and Icy catheter following cardiac arrest.

BACKGROUND: Cardiac arrest causes devastating neurological morbidity and mortality. Mild/moderate hypothermia is neuroprotective after global cerebral ischemia. More rapid controlled attainment of the target temperature may increase efficacy. METHODS: We assessed the safety and feasibility of endovascular cooling in a single arm study of comatose patients who had been successfully resuscitated after cardiac arrest. Core temperature was reduced to a target of 33 degrees C for 24 h using a closed loop endovascular system placed in the inferior vena cava, followed by controlled rewarming. Primary outcomes were speed and accuracy of cooling, survival and GOS after 30 days. RESULTS: Thirteen patients were enrolled, six male, age 60 +/- 19 years. Time from cardiac arrest to return of spontaneous circulation was 14.3 min (range 5-32.5). It took 3h and 39 min (median 210 min, IQ 80-315) to reach 33 degrees C; cooling averaged 0.8 +/- 0.3 degrees C/h (range 0.22-1.12 degrees C/h). Temperature was tightly maintained for all patients averaging 32.7 +/- 0.5 degrees C. Rewarming lasted 18.3 +/- 5.9 h. Five patients (38%) had 30-day Glasgow Outcome Scores of 1-2. Four patients died, none related to the hypothermia procedure. No unanticipated or procedure-related adverse events occurred. CONCLUSION: In comatose survivors of cardiac arrest, hypothermia via endovascular methods is safe and feasible, and target temperatures can be achieved and controlled rapidly and precisely. More studies are needed to assess the efficacy of rapid endovascular hypothermia after cardiac arrest.

Prolactin induces an inward current through voltage-independent Ca2+ channels in Chinese hamster ovary cells stably expressing prolactin receptor.

There is still only limited understanding of the early steps of prolactin (PRL) signal transduction in target cells. Recent studies have identified some of the essential first steps: these include the rapid association of the PRL receptor with JAK tyrosine kinases and tyrosine phosphorylation of a number of proteins, including members of the signal transducer and activator of transcription (Stats) family. On the other hand, binding of PRL to its receptor is rapidly followed by calcium influx. However, PRL-induced ionic events and the related ionic channels involved have not been clearly established. This work was undertaken to characterise the channels responsible for calcium influx and to obtain an insight into their activation processes. Using the patch-clamp technique in the cell-attached configuration, single Ca2+ channel currents were recorded following PRL application (10 nM) in Chinese hamster ovary (CHO) cells stably expressing PRL receptor (CHO-E32). Statistical analysis showed that the recorded currents were voltage-independent, with a slope conductance of 16 pS. Although these channels were present in excised patches, the fact that PRL was unable to activate them suggested that a soluble cytoplasmic component may be required. Application of the purified inositol phosphate, Ins(1,3,4,5)P4 (2 microM), to the inside of the excised patch membrane activated the voltage-independent 16 pS Ca2+ channel. The open probability (Popen) was enhanced. The inositol phosphates Ins(1,2,3,4,5)P5 and Ins(1,4,5)P3 did not affect channel activity while InsP6 (20 microM) had some effect, although less marked than that of Ins(1,3,4,5)P4. Using the anion-exchange HPLC technique, we then studied the effects of PRL (10 nM) on the turnover of inositol phosphates (InsPs) in CHO-E32. Our studies showed that PRL induces rapid increases in the production of Ins(1,3,4,5)P4 (207% at 30 s), InsP5 (171% at 30 s), and InsP6 (241% at 30 s). Conversely, Ins(1,4,5)P3 showed a transient decrease at 5 s, accompanied by a concomitant increase in Ins(1,3,4,5)P4, suggesting that the former could be transiently phosphorylated to produce the latter. Comparison of the production kinetics of Ins(1,4,5)P3, Ins(1,3,4,5)P4, InsP5, and InsP6 indicated the possibility of additional metabolic routes which have yet to be determined. This study suggests that PRL promotes Ca2+ entry through voltage-independent Ca2+ channels that may be activated by Ins(1,3,4,5)P4 and InsP6.

Modulation of voltage-dependent Ca2+ conductance by changing Cl- concentration in rat lactotrophs.

In pituitary cells, voltage-dependent Ca2+ channels play an important role in such physiological processes as exocytosis, secretion, the cell cycle, and proliferation. Thus mechanisms that modulate voltage-dependent Ca2+ channel activity participate indirectly in regulating intracellular Ca2+ concentration. We have shown a new modulating mechanism for voltage-dependent Ca2+ channels by demonstrating that Ca2+ influx is influenced by Cl-. To evaluate the role of Cl- on Ca2+ conductance coupling, we first measured the intracellular Cl- concentration of rat lactotrophs using the Cl(-)-sensitive fluorescence probe sulfopropylquinolinium by simple microspectrofluorometry or combined with electrophysiology. We found an average intracellular Cl- concentration of rat lactotrophs of approximately 60 mM (n = 39). Using the whole cell tight-seal recording technique, we showed that a reduction in external Cl- concentration ([Cl-]o) and a decrease in Cl- conductances affected Ca2+ conductance as measured by Ba2+ movement through the Ca2+ channels (I(Ba)). Low [Cl-]o (39 mM) induced a decrease in Ca2+ entry via voltage-gated Ca2+ channels (-27.75 +/- 4% of normalized I(Ba)). Similarly, blockade of the Cl- conductance by 1 mM 9-anthracene carboxylic acid induced a decrease in I(Ba) (-26 +/- 6% of normalized I(Ba)). This modulation of I(Ba) was inhibited by 24-h pretreatment of the cells with pertussis toxin (1 microg/ml), suggesting that changes in Cl- concentration induced by low [Cl-]o and 9-anthracene carboxylic acid interfered with the phosphorylation of G proteins involved in Ca2+ channel activation. These results suggest a feedback mechanism based on constant interaction between Ca2+ and Cl-. Finally, they also emphasize the physiological role of Cl- in rat lactotrophs.