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Biomedical subjects

A Callahan

Publications and source records attributed to A Callahan.

At least 19 recordsLinked to original sources

Cerebrovascular disease and statins: a potential addition to the therapeutic armamentarium for stroke prevention.

Cerebrovascular disease is the leading cause of disability in Western societies. In the United States, it has been estimated that a stroke occurs every 53 seconds. Consequently, the societal costs attributable to cerebrovascular disease are immense and encourage the medical community to seek new therapies that can reduce stroke's frequency and impact. Although serum lipid levels have not been shown to act as a surrogate marker for stroke, in landmark lipid-lowering trials, statin therapy has been associated with reductions in the incidence of ischemic stroke in patient populations with manifest ischemic heart disease. This observation is supported by a recently published meta-analysis of statin trials that reported an average reduction of about 30% in the incidence of cerebrovascular disease. However, to date, statin studies have only been conducted in patients with, or at high risk for coronary artery disease, who are not truly representative of the overall stroke population. The ongoing Stroke Prevention by Aggressive Reduction of Cholesterol Levels (SPARCL) trial has been designed to prospectively evaluate the benefits of aggressive lipid-lowering therapy on cerebrovascular events in patients who have had a previous stroke or transient ischemic attack, but who have no prior history of coronary artery disease.

Anticholesteremic Agents↗

Post-transcriptional gene silencing in plum pox virus resistant transgenic European plum containing the plum pox potyvirus coat protein gene.

Transgenic plums containing the plum pox potyvirus coat protein (PPV-CP) gene were inoculated with PPV. Infection was monitored by evaluating symptoms, ELISA, and IC-RT-PCR. Transgenic clone C5 was highly resistant to PPV during four years of testing and displayed characteristics typical of post-transcriptional gene silencing (PTGS), including a high level of transgene transcription in the nucleus, low levels of transgene mRNA in the cytoplasm, a complex multicopy transgene insertion with aberrant copies, and methylation of the silenced PPV-CP transgene. The PPV-CP transgene was also methylated in seedlings of C5 and these seedlings were resistant to PPV. Our results show, for the first time, that PTGS functions as a mechanism for virus resistance in a woody perennial species.

Blotting, Southern↗

The use of transgenic fruit trees as a resistance strategy for virus epidemics: the plum pox (sharka) model.

Sharka or plum pox, caused by Plum pox virus (PPV: genus Potyvirus; Family Potyviridae), is the most serious disease of Prunus. Most cultivated Prunus species are highly susceptible and conventional breeding has not produced highly resistant and commercially acceptable varieties. Success in developing virus-resistant herbaceous crops through genetic engineering led us to investigate this approach for resistance to PPV. Our programme aims to develop a biotechnological approach to PPV control that is effective and shown to be environmentally safe. The programme began with the cloning of the PPV coat protein (CP) gene and the development of a transformation system for plum (Prunus domestica). The CP construct was first tested in Nicotiana benthamiana in which it proved effective in producing transgenic plants with varying levels of CP expression. Some of these plants, particularly low PPV CP expressers, were resistant to PPV, or recovered from initial infection. Based on these results plum was transformed using the Agrobacterium tumefaciens system and both low and high PPV CP-expressing transgenic plum lines were obtained. These were inoculated with PPV by bud grafts in the greenhouse. Line C-5 proved to be highly resistant. It contained multiple copies of the insert, produced low levels of PPV CP mRNA, no detectable CP and the insert appeared to be methylated. These characteristics all suggest that the resistance of the C-5 clone is based on post-transcriptional gene silencing (PTGS). Field tests of C-5 and other transgenic lines in Poland, Romania and Spain have demonstrated that such trees when inoculated by bud-grafts allow a low level of PPV multiplication, from which they rapidly recover. C-5 plants exposed to natural infection for 3 years did not become infected, whereas control trees were infected in the first year. Hybrid plums having the C-5 PPV CP insert inherited from C-5 are virus-resistant, demonstrating the usefulness of C-5 as a parent in developing new PPV-resistant plum varieties. Research is in progress on the biorisks of PPV CP transgenic plants. Gene constructs that either produce no CP or CP that cannot be transmitted by aphids have been developed, tested in N. benthamiana and transferred to plum. Studies have begun on the potential for synergistic interactions between the PPV CP gene and the other common viruses of Prunus spp. In the future we will be participating in investigating the toxicity or/and the allergenicity of transgenic fruit products and, more importantly, transgenic lines will be developed that express transgenes only in vegetative parts of the plant and not in the fruit.

Capsid↗

Serum cholesterol and impulsivity in personality disorders.

Decreased serum cholesterol has been associated with impulsive aggressive behaviors. This study was designed to explore the relationship between serum cholesterol levels and measures of impulsive aggression in personality disordered patients. Forty-two personality disordered patients (14 borderline personality disorder, 28 other personality disorders) were included. Fasting serum cholesterol was measured by standard enzymatic assay. An ANOVA was performed with factors of gender and diagnosis, looking at two-way interactions between the factors and serum cholesterol. Patients with borderline personality disorder were found to have significantly lower serum cholesterol than non-borderline personality disorders. A significant interaction effect was also seen between gender and diagnosis with the male patients having lower cholesterol levels. This study suggests there may be a relationship between borderline personality disorder and low serum cholesterol.

Adult↗

Relationships between thyroid hormone and antidepressant responses to total sleep deprivation in mood disorder patients.

BACKGROUND: Acute transient antidepressant effects of sleep deprivation are consistently observed in 50% of depressed patients, but the mechanisms of these, at times, dramatic improvements in mood have not been adequately elucidated. Some, but not all, studies suggest a relationship to increased thyroid-stimulating hormone (TSH) secretion. METHODS: TSH and other thyroid indices were measured at 8:00 AM after a baseline night's sleep and at 8:00 AM following a night of total sleep deprivation (S.D.) in 34 medication-free, affective disorder patients assessed with Hamilton, Beck, and Bunney-Hamburg depression ratings as well as two hourly self-ratings on a visual analog scale. RESULTS: Compared with baseline, S.D. induced highly significant increases in TSH, levothyroxine, free levothyroxine, and triiodothyronine. The 12 S.D. responders tended to have greater TSH increases than the 15 nonresponders (p < .10). The change in Beck depression ratings significantly correlated with the change in TSH (r = -.40, p = .0496, n = 24). CONCLUSIONS: These data are consistent with several other reports of a significant relationship between degree of antidepressant response to S.D. and increases in TSH measured at 8:00 AM near their usual nadir. Acute removal of the sleep-related break on the hypothalamic-pituitary-thyroid axis remains a promising candidate for the mechanism of sleep deprivation-induced improvement in mood in depressed patients.

Adult↗

Rational polypharmacy in the bipolar affective disorders.

Bipolar affective illness represents a syndrome not readily treated by single agents. Approximately 50% of patients are inadequately responsive to lithium and the majority of patients require supplemental antidepressants, antimanic, antipsychotic or hypnotic medications. These traditional adjunctive medications are associated with potential problems. Antidepressants may precipitate mania (at a rate about double that of placebo) or cause cycle acceleration. Neuroleptics may be associated with either more profound or longer depressive phases, and clearly increase the risk of tardive dyskinesia, to which bipolar patients appear particularly predisposed. Moreover, there are subgroups of patients who are known to be poorly responsive to lithium. These include patients with rapid cycling, dysphoric mania, co-morbid drug or alcohol abuse, a pattern of depression-mania-well interval (D-M-I as opposed to the M-D-I pattern), and patients without a family history of bipolar illness in first-degree relatives. There is increasing recognition that the anticonvulsants carbamazepine and valproate are effective alternatives or adjuncts to lithium in the acute and long-term treatment of bipolar illness. Ideally, one would want to assess whether patients who were unresponsive to lithium were responsive to an anticonvulsant alone prior to utilizing lithium in addition to anticonvulsant combination therapy. However, from the clinical perspective, it is often more expedient to use an anticonvulsant adjunctively to lithium to assess the efficacy of this combination and establish mood stabilization. When lithium is not discontinued, the increased morbidity during lithium withdrawal also would not occur and would not confound the evaluation of the new agent. We suggest the initial use of acute adjuncts to lithium with the anticonvulsants carbamazepine or valproate (instead of neuroleptics) so that their efficacy can be assessed in the individual's acute episode, with the likelihood of a positive response in longer-term prophylaxis. Hypnotic benzodiazepines with anticonvulsant properties, such as clonazepam or lorazepam, are often used to help to induce sleep in escalating bipolar patients, and may be useful adjuncts as well. Patients who were inadequately responsive to either carbamazepine or valproate alone may be responsive to the anticonvulsant combination. In a similar fashion, one can also utilize several mood-stabilizing drugs (lithium and an anticonvulsant such as carbamazepine or valproate) in the treatment of depressive breakthroughs, and then augment this combination (if necessary) with a catecholamine-active antidepressant such as bupropion or a serotonin-selective reuptake inhibitor (SSRI) such as fluoxetine, paroxetine, sertraline or if necessary a monoamine oxidase inhibitor (MAOI). Once the patient has responded to a combination of drugs, it becomes problematic to decide whether the last agent added was the crucial ingredient in helping the patient achieve remission or that remission might have occurred with this agent alone. A conservative approach would have merit in patients who are finally stabilized on complex polypharmacy regimens only after many years of sequential trials; in this instance, the potential risk of re-exacerbating the illness with a taper of one of the drugs in the regimen. Rational polypharmacy should thus be implemented with careful delineation of the prior course of illness (typically using life chart methodology) and targeted treatment outcomes titrated against side effects, using sequential clinical trials in individual patients who have not adequately responded to monotherapy. In this fashion, it is hoped that pharmacodynamic differences among agents can be maximized and pharmacokinetic and side effects minimized.

Anticonvulsants↗

Daily repetitive transcranial magnetic stimulation (rTMS) improves mood in depression.

Converging evidence points to hypofunction of the left prefrontal cortex in depression. Repetitive transcranial magnetic stimulation (rTMS) activates neurons near the surface of the brain. We questioned whether daily left prefrontal rTMS might improve mood in depressed subjects and report a pilot study of such treatment in six highly medication-resistant depressed inpatients. Depression scores significantly improved for the group as a whole (Hamilton Depression Scores decreased from 23.8 +/- 4.2 (s.d.) at baseline to 17.5 +/- 8.4 after treatment; t = 3.03, 5DF, p = 0.02, two-tailed paired t-test). Two subjects showed robust mood improvement which occurred progressively over the course of several weeks. In one subject, depression symptoms completely remitted for the first time in 3 years. Daily left prefrontal rTMS appears to be safe, well tolerated and may alleviate depression.

Affect↗

Parental age in the blepharophimosis, ptosis, epicanthus inversus, telecanthus complex.

Maternal and paternal age and birth order of 14 sporadic cases of the autosomal dominant blepharophimosis-ptosis-epicanthus inversus-telecanthus (BPEI) phenotype were compared to similar statistics from control individuals. Correlation coefficients were determined for paternal age and incidence, maternal age and incidence, and birth order and incidence. The partial correlation coefficient of the father's age and incidence with maternal age and birth order held constant was -0.02 and that for the mother's age and incidence with paternal age and birth order held constant was 0.57. Maternal age seems to have a stronger influence than the paternal age in this group of BPEI patients.

Abnormalities, Multiple↗

Mohs micrographic surgery for periorbital skin cancer.

The authors have illustrated the use of the Mohs technique on periorbital skin cancer. The indications for the technique are documented for eyelid and canthal neoplasia, and the case histories illustrate the potential danger of skin cancer in this area. It is the well balanced team of micrographic surgeons and reconstructive surgeons that will give the patient the best result.

Adult↗

Induction of 33-kD and 60-kD Peroxidases during Ethylene-Induced Senescence of Cucumber Cotyledons.

Ethylene enhanced the senescence of cucumber (Cucumis sativus L. cv ;Poinsett 76') cotyledons. The effect of 10 microliters per liter ethylene was inhibited by 1 millimolar silver thiosulfate, an inhibitor of ethylene action. An increase in proteins with molecular weights of 33 to 30 kilodaltons and lower molecular weights (25, 23, 20, 16, 12, and 10 kilodaltons) were observed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels after ethylene enhanced senescence. The measurement of DNase and RNase activity in gels indicated that these new proteins were not nucleases. Two proteins from ethylene-treated cotyledons were purified on the basis of their association with a red chromaphore and subsequently were identified as peroxidases. The molecular weights and isoelectric points (pI) of two of these peroxidases were 33 kilodaltons (cationic, pI = 8.9) and 60 kilodaltons (anionic, pI = 4.0). The observation that [(35)S]Na(2)SO(4) was incorporated into these proteins during ethylene-enhanced senescence suggests that these peroxidases represent newly synthesized proteins. Antibodies to the 33-kilodalton peroxidase precipitated two in vitro translation products from RNA isolated from ethylene-treated but not from control cucumber seedlings. This indicates that the increase in 33-kilodalton peroxidase activity represents de novo protein synthesis. Both forms of peroxidase degraded chlorophyll in vitro, which is consistent with the hypothesis that peroxidases have catabolic or scavenging functions in senescent tissues.

Journal Article↗

Complications following enucleation and implantation of multiple glass spheres in the orbit.

The technique of subperiosteal implantation of multiple, small glass beads for correction of enophthalmos associated with anophthalmos was first described in 1967. Reported complications of this procedure include ptosis, anesthesia of the distribution of the supraorbital or infraorbital nerve, and migration of the implants into the orbit or sinuses. A case of orbital cellulitis has been reported. We now report a case in which the extremely serious complication of intracranial migration of glass bead implants, with subsequent cerebrospinal fluid leak, occurred 17 years postimplantation.

Cerebrospinal Fluid Rhinorrhea↗

The power spectrum analyser as an indicator of cerebral ischaemia during carotid endarterectomy.

Stroke is a potential major complication of carotid endarterectomy and may be caused by cerebral ischaemia or embolisation from the operative site. Conventional EEG monitoring has been used intraoperatively to identify periods of cerebral ischaemia, but this monitoring technique can be difficult to operate and interpret in the operating room. This study reports the use of a new signal analyser, the power spectrum analyser (PSA-1, Neurologics, Inc., Nashville, Tennessee), and its impact on active patient management. Thirty-six patients undergoing carotid endarterectomies were monitored with the PSA-1 in conjunction with routine EEG. Eight patients (22%) showed evidence of ischaemia 22 times on both PSA-1 and routine EEG. At no time did the routine EEG show evidence of ischaemia when the PSA-1 did not. The PSA-1 has proven to be a reliable neurophysiologic monitor for the identification of periods of cerebral ischaemia. Use of this small, easily operated and interpreted machine could enhance safety in operating rooms lacking sufficient resources to use conventional EEG machines.

Aged↗