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Biomedical subjects

R Davis

Publications and source records attributed to R Davis.

At least 181 records · Page 10Linked to original sources
PubMed1996

Fosinopril: a reappraisal of its pharmacology and therapeutic efficacy in essential hypertension.

Fosinopril is a phosphinic acid derivative which undergoes rapid hydrolysis after oral administration to the active diacid ACE inhibitor fosinoprilat. Cardiotropic effects have been associated with the drug, and the compensatory dual elimination route of fosinopril via renal and hepatic systems offers an opportunity for ACE inhibitor treatment of hypertension in patients with renal or hepatic impairment. Comparative trials of monotherapy with fosinopril 10 to 40 mg/day have demonstrated antihypertensive efficacy equivalent to that of sustained release nifedipine 40 mg/day, hydrochlorothiazide 25 to 50 mg/day, enalapril 5 to 10 mg/day amlodipine 5 to 10 mg/day and sustained release verapamil 240 to 480 mg/day, and superior to that of isradipine 5 mg/day. The efficacy of combination therapy with fosinopril 10 to 20 mg/day and hydrochlorothiazide 12.5 mg/day was significantly superior to that of hydrochlorothiazide alone, tended to be superior to that of fosinopril 20 mg/day alone and was similar to that of sustained release nifedipine 40 mg/day alone. The combination of fosinopril/chlorthalidone 20 to 40/25 mg/day was as effective as propranolol/chlorthalidone 80 to 160/25 mg/day. The incidence of adverse effects associated with fosinopril is low, and cough may possibly occur less often with this drug than with other ACE inhibitors. Fosinopril thus offers an effective and well tolerated option for the treatment of hypertension in adult and elderly patients, including those with renal or hepatic impairment.

Adult↗
PubMed1996

Ciprofloxacin. An updated review of its pharmacology, therapeutic efficacy and tolerability.

Ciprofloxacin is a broad spectrum fluoroquinolone antibacterial agent. Since its introduction in the 1980s, most Gram-negative bacteria have remained highly susceptible to this agent in vitro; Gram-positive bacteria are generally susceptible or moderately susceptible. Ciprofloxacin attains therapeutic concentrations in most tissues and body fluids. The results of clinical trials with ciprofloxacin have confirmed its clinical efficacy and low potential for adverse effects. Ciprofloxacin is effective in the treatment of a wide variety of infections, particularly those caused by Gram-negative pathogens. These include complicated urinary tract infections, sexually transmitted diseases (gonorrhoea and chancroid), skin and bone infections, gastrointestinal infections caused by multiresistant organisms, lower respiratory tract infections (including those in patients with cystic fibrosis), febrile neutropenia (combined with an agent which possesses good activity against Gram-positive bacteria), intra-abdominal infections (combined with an antianaerobic agent) and malignant external otitis. Ciprofloxacin should not be considered a first-line empirical therapy for respiratory tract infections if penicillin-susceptible Streptococcus pneumoniae is the primary pathogen; however, it is an appropriate treatment option in patients with mixed infections (where S. pneumoniae may or may not be present) or in patients with predisposing factors for Gram-negative infections. Clinically important drug interactions involving ciprofloxacin are well documented and avoidable with conscientious prescribing. Recommended dosage adjustments in patients with impaired renal function vary between countries; major adjustments are not required until the estimated creatinine clearance is < 30 ml/min/1.73m2 (or when the serum creatinine level is > or = 2 mg/dl). Ciprofloxacin is one of the few broad spectrum antibacterials available in both intravenous and oral formulations. In this respect, it offers the potential for cost savings with sequential intravenous and oral therapy in appropriately selected patients and may allow early discharge from hospital in some instances. In conclusion, ciprofloxacin has retained its excellent activity against most Gram-negative bacteria, and fulfilled its potential as an important antibacterial drug in the treatment of a wide range of infections. Rational prescribing will help to ensure the continued clinical usefulness of this valuable antimicrobial drug.

Anti-Infective Agents↗
PubMed1996

Dexfenfluramine. An updated review of its therapeutic use in the management of obesity.

Dexfenfluramine increases serotonergic activity by stimulating serotonin (5-hydroxytryptamine; 5-HT) release into brain synapses, inhibiting its reuptake into presynaptic neurons and by directly stimulating postsynaptic serotonin receptors. On the basis of the serotonin hypothesis of appetite control, these actions would be expected to reduce appetite and, consequently, bodyweight. Studies conducted in animals and in overweight patients with and without associated disorders have confirmed the weight-reducing efficacy and good tolerability of dexfenfluramine. In 3-month clinical studies in obese patients, weight reductions with dexfenfluramine 15mg twice daily combined with dietary support were significantly higher than those achieved with placebo and similar to those with ephedrine/caffeine 20/20mg 3 times daily, sibutramine 10mg once daily and fluoxetine 60 mg/day. Furthermore, dexfenfluramine recipients with non-insulin-dependent diabetes mellitus, hyperlipidaemia or hypertension consistently show improvements in glycaemic control, blood lipid profiles and blood pressure. 12-month trial results indicate that most weight loss occurs in the initial 6 months and appears to be maintained for a further 6 months. Weight regain after withdrawal of treatment in 12-month studies demonstrates that dexfenfluramine is effective in maintaining a stable bodyweight at a lower level than placebo and in limiting food intake over this time period. Commonly reported adverse events with dexfenfluramine include diarrhoea, tiredness, dry mouth and somnolence; these symptoms are generally mild and transient. Approximately 7 and 10% of dexfenfluramine recipients in short and long term studies withdrew because of adverse events. Dexfenfluramine was better tolerated than ephedrine/caffeine and fluoxetine in short term studies. Obesity is a chronic condition that is accompanied by a number of metabolic complications. It is a significant health problem in developed countries, and as a major risk factor for many chronic diseases, including diabetes and cardiovascular disease, the economic burden of this condition is considerable. As with other chronic conditions, there is a role for pharmacological intervention in patients with severe obesity. However, drugs should be considered as only one component of a weight-control programme, since additional lifestyle modification is required to maintain weight loss. The promising data on the long term efficacy and tolerability of dexfenfluramine as well as its favourable effects on risk factors associated with obesity requires confirmation in long term studies. In the meantime, dexfenfluramine should be considered a valuable adjunct to a reduced-calorie diet in the management of severe obesity, particularly in patients with associated disorders and those unsuccessful with conventional weight loss measures. Available data support the use of the drug for up to 1 year to maintain weight loss and thus dexfenfluramine should be considered for long term administration.

Animals↗
PubMed1996

Sertraline. A pharmacoeconomic evaluation of its use in depression.

Depression is a common condition that is often unrecognised, misdiagnosed and/or undertreated. It is associated with substantial direct, indirect and intangible costs. The indirect costs of lost earnings/productivity and premature death account for the majority of these costs; drug costs account for only about 1 to 2% of total costs and about 10 to 12% of direct costs. Thus, better recognition and appropriate treatment of depression would increase the direct costs associated with this illness, but would also have the potential to greatly reduce indirect costs and consequently the overall cost of depression. Because of their higher acquisition costs relative to tricyclic antidepressants (TCAs), there has been much debate about whether the use of sertraline or other selective serotonin reuptake inhibitors (SSRIs) for first-line treatment of depression can be justified. While these agents have similar efficacy to TCAs, they are better tolerated and have a lower risk of death on overdosage. Despite the large economic burden of depression on society, pharmacoeconomic data on sertraline and antidepressant drugs in general are scarce. Most of the available studies on sertraline are limited to considerations of direct costs and do not assess costs from a societal perspective. In addition, a number of studies have significant methodological problems which limit determination of meaningful conclusions. Nonetheless, data from 2 more recent studies with fewer methodological problems than earlier studies indicated that sertraline was more cost-effective than TCAs because of fewer psychiatrist consultations, and less costly than fluoxetine because of fewer absences from work and fewer medical consultations. The cost-utility ratio of maintenance therapy of depression with sertraline appears to fall within the range of accepted cost-utility ratios of common healthcare interventions. Thus, studies to date have generally shown that overall treatment costs with sertraline and other SSRIs are no greater than those for TCAs; this is despite the lower acquisition costs of the latter agents. Therefore, it is clear from these data that it is misleading to classify antidepressant agents as expensive or inexpensive based solely on their acquisition costs. Sertraline, therefore, can be considered as a first-line alternative to TCAs and other SSRIs for the treatment of depression on both clinical and pharmacoeconomic grounds.

1-Naphthylamine↗
PubMed1996

Ictal and interictal technetium-99m-bicisate brain SPECT in children with refractory epilepsy.

UNLABELLED: Identification of epileptogenic foci in patients with refractory epilepsy remains a significant diagnostic challenge. Magnetic resonance imaging studies frequently fail to reveal an anatomic origin for the seizures, and scalp electroencephalography is often limited to identification of the involved hemisphere. Functional imaging modalities such as PET and SPECT are more promising tools for this application because they reflect the functional pathology associated with the seizure. These changes are more pronounced ictally, but until recently, no radiopharmaceutical was available that could be used routinely for ictal SPECT. The present study was therefore undertaken to determine whether 99mTc-bicisate could be used in ictal SPECT in pediatric patients with refractory epilepsy, to compare the patterns of ictal and interictal blood flow in these patients and to compare the localization information provided by ictal SPECT with that available from other techniques. METHODS: Technetium-99m-bicisate/SPECT was compared prospectively with scalp EEG for its ability to identify a possible seizure focus in pediatric patients with refractory epilepsy. Ictal and interictal SPECT studies were performed in 10 patients (3-19 yr old, mean age 10.9 +/- 4.3 yr; 7 female, 3 male) in whom MRI scans revealed no lesions that might be responsible for the seizures. RESULTS: Ictal SPECT was performed in all patients, and all ictal studies revealed focal perfusion abnormalities. By comparison, four of the interictal SPECT studies showed regional hypoperfusion that corresponded to the regions of hyperperfusion in the ictal studies, and three showed regional hyperperfusion corresponding to the hyperperfused regions in the ictal studies. Three interictal studies revealed no abnormal perfusion. Scalp EEG provided localization information in five patients. CONCLUSION: These initial results suggest that ictal SPECT with 99mTc-bicisate is a more promising tool for the identification of epileptogenic foci than interictal SPECT or scalp EEG in patients without focal abnormalities on MRI.

Brain↗
PubMed1996

Summary of track A: basic science.

AIM: To review Track A, which is organized into five broad areas of emphasis. TOOLS: A variety of new virologic tools are allowing researchers to more effectively evaluate many aspects of HIV, from various therapies and vaccine candidates to the recombination and international spread of genotypes. PATHOGENESIS: The recent understandings of HIV-1 pathogenesis have led to potential new treatment strategies of early aggressive treatment with combination drugs and the potential for biologic or immunologic therapy directed to blocking viral entry through second receptors. TREATMENT: HIV treatment focused on chemical/drug advances and treatment, and immunologic/genetic advances. Some areas of development include optimizing combination therapies using the oncology model; continued work on new preclinical compounds (e.g. integrase and tat/rev inhibitors); evaluation of viral reduction in all compartments; and resistance surveillance and prevention. Biologics, including fusin/CC-CKR5 inhibitors and CD8 HIV-1 suppressor factors, ex vivo expansion of T cells and in vivo expansion of effector CD8 cells continue to be developed as possible future treatments. VACCINES: In order to obtain worldwide control over HIV, we must have a universally effective vaccine. The question remains as to what specifically is required for a protective response. Mechanisms of CD8 suppression, and cellular and antibody correlates of protection were discussed as areas of research that may shed light on the critical protective immune response. GENOTYPES: Discussion of HIV genotypes focused on international subtypes, correlates of diversity, and HIV-1 recombination. Numerous groups have shown an international intermixing of HIV-1 strains. Recombination during transcription was found to lead to extensive genomic shift and increased diversity, which may also increase HIV-1 fitness and enhance transmission. CONCLUSIONS: The spread and adaptation of HIV-1 is occurring independently of borders. Therefore, HIV-1 research must be global; vaccine development must be international in concept and application; collaboration in all areas is essential for success in combating HIV; and finally, the challenge for the future will be to actively involve all basic scientists in the science of the international epidemics.

AIDS Vaccines↗
PubMed1995

Differential effects of UV-B and UV-C components of solar radiation on MAP kinase signal transduction pathways in epidermal keratinocytes.

Exposure to solar ultraviolet (UV) light is a major cause of skin cancer, the most common human neoplasm. The earth's upper atmosphere absorbs the high energy UV-C wavelengths (100-280 nm), while allowing transmission of UV-B (280-320 nm) and UV-A (320-400 nm). It is therefore UV-B and to some extent UV-A, that contributes to most human skin malignancies. We report that the exposure of cultured keratinocytes or skin to UV-C radiation causes activation of MAP kinases (ERK and JNK). In contrast, the solar radiation associated with skin cancer (UV-B) was an ineffective activator of the ERK and JNK signal transduction pathways. Therefore, while exposure of epidermal cells to UV-C radiation under laboratory conditions causes marked activation of MAP kinase signal transduction pathways, only a low level of MAP kinase signaling is involved in the response of skin to biologically relevant solar radiation.

Animals↗
PubMed1995

Studies of Schizosaccharomyces pombe DNA polymerase alpha at different stages of the cell cycle.

The status of Schizosaccharomyces pombe (fission yeast) DNA polymerase alpha was investigated at different stages of the cell cycle. S.pombe DNA polymerase alpha is a phosphoprotein, with serine being the exclusive phosphoamino acid. By in vivo pulse labeling experiments DNA polymerase alpha was found to be phosphorylated to a 3-fold higher level in late S phase cells compared with cells in the G2 and M phases, but the steady-state level of phosphorylation did not vary significantly during the cell cycle. Tryptic phosphopeptide mapping demonstrated that the phosphorylation sites of DNA polymerase alpha from late S phase cells were not the same as that from G2/M phase cells. DNA polymerase alpha partially purified from G1/S cells had a different mobility in native gels from that from G2/M phase cells. The partially purified polymerase alpha from G1/S phase cells had a higher affinity for single-stranded DNA than that from G2/M phase cells. Despite the apparent differences in cell cycle-dependent phosphorylation, mobility in native gels and affinity for DNA, the in vitro enzymatic activity of the partially purified DNA polymerase alpha did not appear to vary during the cell cycle. The possible biological significance of these cell cycle-dependent characteristics of DNA polymerase alpha is discussed.

Cell Cycle↗
PubMed1995

Comparative anterograde amnestic and anticonvulsant effects of two types of NMDA receptor antagonists: MK-801 and HA-966.

The anterograde amnestic effects of non-competitive NMDA antagonists MK-801 and HA-966 on classic fear conditioning in goldfish (Carassius auratus) were examined in a series of experiments. Experiments 1 and 2 contrasted the anterograde amnestic effects of MK-801, (+)HA-966, and (-)HA-966. Experiment 3 examined the effects of MK-801 and (+)HA-966 on the expression of conditioned responses. Experiments 4 and 5 investigated whether the potency of MK-801, (+)HA-966 or (-)HA-966 in blocking NMDA-induced convulsions paralleled their potency in producing amnesia. The results showed that MK-801 was more potent than (+)HA-966 in producing anterograde amnesia and impairing expression, while (-)HA-966 did not produce anterograde amnesia. The anticonvulsant potency of MK-801, (+)HA-966, and (-)HA-966 paralleled their amnestic potency. These findings suggested that MK-801 and (+)HA-966 produced anterograde amnesia by their specific antagonism of the NMDA receptor complex.

Amnesia↗
PubMed1995

In vitro and in vivo evaluation of the subtype-selective muscarinic agonist PD 151832.

PD 151832 is a potent partial muscarinic agonist that displays a high level of functional selectivity for the muscarinic m1 receptor subtype, as evidenced by its selective stimulation of PI turnover and cellular metabolic activity in transfected Hm1-CHO cells at concentrations that produce minimal stimulation of other cloned human muscarinic receptors. PD 151832 enhanced the amplification of Hm1-transfected NIH-3T3 cells at concentrations lower than those required to produce similar effects in Hm2 or Hm3-transfected cells. The functional m1 selectivity of PD 151832 is consistent with its improvement of mouse water maze performance at doses far lower than those required to produce peripheral parasympathetic side effects.

3T3 Cells↗
PubMed1995

A cell type-specific silencer in the human choline acetyltransferase gene requiring two distinct and interactive E boxes.

We have previously reported that cholinergic neuron-specific expression of the human choline acetyltransferase gene is mediated by two co-operative silencers. We have now localized the proximal silencer to the region from nucleotide -2195 to -2409, which contains two distinct E boxes (CACCTG and CATGTG). Deletion or mutation of either of these E boxes results in a loss of silencer activity. There are specific nuclear proteins in adrenergic cells which bind to each of the two E boxes. However, nuclear proteins from cholinergic cells only bind the 5' E box not the 3' E box. It is this interaction which appears to be the cause of the inactivity of this silencer in these cells.

Base Sequence↗