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Biomedical subjects

S Donovan

Publications and source records attributed to S Donovan.

At least 19 recordsLinked to original sources

Candidate gene isolation and comparative analysis of a commonly deleted segment of 7q22 implicated in myeloid malignancies.

Monosomy 7 and deletion of 7q are recurring abnormalities in malignant myeloid diseases. Here we extensively characterize an approximately 2-Mb commonly deleted segment (CDS) of 7q22 bounded by D7S1503 and D7S1841. Approximately 1.8 Mb of sequence have been generated from this interval, facilitating the construction of a transcript map that includes large numbers of genes and ESTs. The intron/exon organization of seven genes and expression patterns of three genes were determined, and leukemia samples were screened for mutations in five genes. We have used polymorphic markers from this region to examine leukemia cells for allelic loss within 7q22. Finally, we isolated mouse genomic clones orthologous to several of the characterized human genes. Fluorescence in situ hybridization studies using these clones indicate that a region of orthologous synteny lies on proximal mouse chromosome 5. These resources should greatly accelerate the pace of candidate gene discovery in this region.

Acute Disease↗

Forensic entomology: what can maggots tell us about murders?

On 29 September 1935, the dismembered remains of two human bodies were discovered in a ravine known as the Devil's Beef Tub, in Dumfriesshire, Scotland. On examination, it was apparent that many of the body parts were infested by maggots.

Animals↗

Refractory amiodarone-associated thyrotoxicosis: an indication for thyroidectomy.

BACKGROUND: Tasmania is an area of endemic iodine deficiency. Amiodarone is a class III anti-arrhythmic drug that is widely used for the management of ventricular and supraventricular tachydysrhythmias. Individuals from areas of endemic iodine deficiency appear more likely to manifest hyperthyroidism following amiodarone therapy, whereas hypothyroidism is a more frequent complication in iodine-replete communities. METHODS: Cases series. The clinical and biochemical response to medical and surgical management of five consecutive Tasmanian patients presenting with severe type-II amiodarone-associated thyrotoxicosis was reviewed. RESULTS: Five patients were identified. Combinations of antithyroid therapy including propylthiouracil, lithium carbonate, dexamethasone and cholestyramine were used. Thyroidectomy was required in two cases (40%) due to severe unremitting thyrotoxicosis despite combined drug regimens. Anaesthesia and total thyroidectomy were undertaken without complication despite the presence of severe hyperthyroidism at the time of surgery. In both cases thyroid histopathology demonstrated degenerative and destructive follicular lesions with multinuclear cell infiltrate and focal fibrosis. CONCLUSION: Amiodarone-associated thyrotoxicosis may be severe and refractory to medical therapy. Despite the potential risks of anaesthesia associated with uncontrolled thyrotoxicosis, thyroidectomy should be considered in the setting of life-threatening thyrotoxicosis.

Acute Disease↗

Effect of hand sanitizer use on elementary school absenteeism.

BACKGROUND: Several studies have indicated a connection between handwashing and illness-related absenteeism in school settings. The difficulty of ensuring consistent and effective handwashing among student populations has also been noted. The purpose of this study was to assess the effectiveness of the use of an alcohol gel hand sanitizer in the classroom to help decrease the illness-related absentee rate for elementary school students. METHODS: This study involved 5 individual school districts, 16 individual schools, and more than 6000 students in Delaware, Ohio, Tennessee, and California. Individual schools in each district were paired into product and control groups. In the product group schools, an alcohol gel hand sanitizer was used by the students and staff when entering and leaving the classroom. Absenteeism due to infection was recorded, and the data were statistically analyzed. RESULTS: The overall reduction in absenteeism due to infection in the schools included in this study was 19.8% for schools that used an alcohol gel hand sanitizer compared with the control schools (P <.05). Data from the school system with the largest teacher population (n = 246) showed that teacher absenteeism decreased 10.1% (trend) in the schools where sanitizer was used. CONCLUSION: Elementary school absenteeism due to infection is significantly reduced when an alcohol gel hand sanitizer is used in the classroom as part of a hand hygiene program.

Absenteeism↗

Deliberate self-harm and antidepressant drugs. Investigation of a possible link.

BACKGROUND: It is not clear if the frequency of deliberate self-harm (DSH) is the same in patients taking different pharmacological classes of antidepressant drugs. AIMS: To compare the frequency of DSH in patients who had been prescribed a tricyclic antidepressant (TCA) or a selective serotonin reuptake inhibitor (SSRI) prior to the DSH event. METHOD: This was a prospective study in 2776 consecutive DSH cases attending an accident and emergency department. The incidence of DSH in TCA-treated cases and SSRI-treated cases is expressed as number of DSH events per 10 000 prescriptions of each antidepressant. RESULTS: Significantly more DSH events occurred following the prescription of an SSRI than that of a TCA (P<0.001). The occurrence of DSH was highest with fluoxetine and lowest with amitriptyline. CONCLUSIONS: Merely prescribing safer-in-overdose antidepressants is unlikely to reduce the overall morbidity from DSH.

Adolescent↗

Taxol, vincristine or nocodazole induces lethality in G1-checkpoint-defective human astrocytoma U373MG cells by triggering hyperploid progression.

In this report, we describe a novel lytic mechanism exploited by antimicrotubule drugs (AMDs) such as Taxol which are frequently used to treat multiple human cancers including breast and ovarian cancers. In cells lacking the G1-arresting capacity due to the defect in retinoblastoma or p53 gene function, AMDs trigger hyperploid progression and death. The hyperploid progression occurs via continued cell-cycle progression without cell division. Blocking hyperploid progression through hydroxyurea or ectopically expressed p27(Kip1), a G1-specific Cdk inhibitor, abrogates AMD cytotoxicity. Thus, AMDs induce lethality in G1-checkpoint-defective cells by triggering hyperploid progression. The phenomenon is reminiscent of that observed previously with bub-1 yeast mutant. The potential significance of this finding lies in that hyperploid progression-mediated death may be exploited to develop a therapy with tumor-specificity at the genetic level. As a large fraction of human cancers are mutated in p53 gene, it may have a wide therapeutic applicability.

Astrocytoma↗

Atypical features and treatment response in the National Institute of Mental Health Treatment of Depression Collaborative Research Program.

Because depression with atypical features is poorly responsive to imipramine, treatment trials including a tricyclic antidepressant arm should assess depressive subtype. Sotsky and Simmens had previously reanalyzed data from the National Institute of Mental Health Treatment of Depression Collaborative Research Program (TDCRP) providing independent confirmation that imipramine is ineffective for patients with atypical features. The TDCRP was a 16-week study in which 239 outpatients with major depression were randomly assigned to cognitive behavior therapy (CBT), interpersonal psychotherapy (IPT), imipraminecase management (IMI-CM), or pill placebo-case management (Pbo-CM). We used Sotsky and Simmens' algorithm to investigate the effect of diagnostic subtype on all four treatments. Hierarchical multiple regression analyses demonstrated IMI-CM benefit relative to Pbo-CM in patients without but not in those with atypical features. These analyses did not demonstrate differential psychotherapy efficacy between depressive subtypes. In conclusion, subsequent analyses of the TDCRP study demonstrated the need to identify the subgroup of depressed patients who have atypical features. Failure to identify this subtype underestimates imipramine's benefit in the appropriately treated subgroup. Comparisons of other treatments with imipramine may be misleading if they do not account for diagnostic subtype.

Algorithms↗

Wound infection and wound swabbing.

There is a significant lack of knowledge in relation to the identification and management of infected wounds. More attention should be given in nurse education to knowing when and how to obtain would swabs. Wound swabbing practices should be standardised.

Decision Trees↗

Cdc6p-dependent loading of Mcm proteins onto pre-replicative chromatin in budding yeast.

The Cdc6 protein is essential for the assembly of pre-replicative complexes (pre-RCs) at origins of DNA replication in the budding yeast Saccharomyces cerevisiae. This reaction is blocked in vivo by the cyclin-dependent kinase Cdc28p, together with its regulatory subunits, the B type cyclins that are present throughout S, G2, and M phases. Because the destruction of B type cyclins and the consequent inactivation of the kinase are essential for exit from mitosis, pre-RC formation can only occur after passage through mitosis. Therefore, pre-RC formation has been proposed to be essential for coupling S phase and mitosis and for limiting DNA replication to once per cell cycle. The Mcm2-7 family of proteins has been implicated in limiting replication to once per cell cycle from experiments with Xenopus egg extracts. Here we show that the Mcm proteins of budding yeast are abundant and are quantitatively found in a chromatin-enriched fraction specifically during the G1 phase of the cell cycle. This chromatin binding depends on the de novo synthesis of Cdc6p, providing evidence that a conserved biochemical pathway plays a critical role in coordinating DNA replication with mitosis in both yeast and higher eukaryotes. Cdc6p and the origin recognition complex can be selectively removed from this chromatin-enriched fraction without removing the Mcm proteins. From these results, we propose that Cdc6p (and the origin recognition complex) nucleates the binding of Mcm proteins to chromatin, but once bound, the Mcm proteins appear to interact tightly with some other component of chromatin.

Cell Cycle↗

Outcome of cognitive-behavioral therapy for depression: relation to hemispheric dominance for verbal processing.

Unmedicated depressed outpatients were tested on dichotic syllable and complex tone tests prior to receiving 16 weekly sessions of cognitive therapy (n = 31) or 6-12 weeks of placebo treatment (n = 45). Cognitive-therapy responders had twice the right-ear (left hemisphere) advantage for syllables when compared with nonresponders but did not differ from nonresponders on the nonverbal task. The larger right-ear advantage in cognitive-therapy responders was due to better right-ear accuracy; they did not differ from nonresponders in left-ear accuracy. No differences in perceptual asymmetry or accuracy were found between placebo responders and nonresponders. Right-ear accuracy for syllables was the best predictor of response to cognitive therapy in a logistic regression analysis. The findings suggest that greater left-hemisphere advantage for verbal processing is associated with more favorable outcome of cognitive therapy for depression.

Adult↗

Nosology of chronic mood disorders.

In attempting to assess the complex relationship of chronic depression with other conditions to which it may be a predisposition, an accompaniment, or a consequence of, a few concluding caveats may be useful. It must be recognized that chronic depression has a wide variety of different presentations and causes. Current definitions of major depressive disorder and dysthymic disorder may create a misleading distinction of what may be two aspects of the overall course of a depressive disorder. Furthermore, much of what is considered to be comorbidity of other disorders with chronic depression actually may be a complex syndrome with a common pathogenesis.

Adult↗

The management of treatment resistance in depressed patients with substance use disorders.

General principles for treatment-resistant psychiatric disorders include reevaluation of diagnosis, search for hidden comorbidity, and systematic trials of alternative treatments and treatment combinations. For the combination of refractory depression and substance abuse, alternative approaches to both problems need to be tried, as suggested in the decision tree in Figure 1. Recognition of a previously unappreciated substance abuse problem or institution of more effective substance abuse treatment (see Table 2) can improve the outcome of depression. Hospitalization is often useful to enforce abstinence and to clarify the diagnosis of depression, and is particularly indicated if substance abuse is severe. If hospitalization is not possible then features of the history, such as relative onsets of depression and substance abuse, can be considered to support the diagnosis. TCAs and SSRIs have been studied in depressed substance abusers and should be the first lines of treatment. If these fail, other medications, medication combinations, or ECT should be considered, extrapolating from the general literature on treatment of refractory depression. In general, single agents should be preferred to combinations, as this reduces the odds of drug-drug interactions in patients who may abuse a variety of substances. Impairment by antidepressant agents of hepatic metabolism of other drugs should be considered, and sertraline, for example, might be preferred over fluoxetine for this reason. For each case, the known side effects and risks of a given antidepressant medication must be considered in the context of a patient's substance abuse pattern and medical problems. Such risk:benefit analyses are often difficult, as illustrated in the cases presented. Finally, although it is a rare occurrence, antidepressant medications that are anticholinergic or amphetamine-like may be abused, and this needs to be monitored. Alcohol or drug abuse history is a likely risk factor for benzodiazepine abuse, and benzodiazepines should, therefore, be avoided or used with caution. These recommendations for management of treatment-resistant depression with substance abuse are based upon clinical experience and extrapolation from the literature on treatment-resistant depression, treatment of substance abuse, and initial treatment of depression in substance abusers with TCAs and SSRIs. More treatment research is needed, particularly on Type IV patients where both depression and substance use are treatment resistant.

Adult↗

Replication origins in eukaroytes.

Recent experiments in budding yeast and Xenopus have provided new insights into the regulation of eukaroytic DNA replication. The multi-subunit origin recognition complex plays a key role in initiation, remaining bound at origins of replication during most of the cell cycle. Early in the cell cycle, Cdc6 and the Mcm proteins 'reset' chromatin for another round of DNA replication. Cyclin-dependent kinases appear to play a dual role, both in activating replication origins and blocking the formation of new pre-replicative complexes; thus limiting replication to once per cell cycle.

Animals↗

Effects of insulin, insulin-like growth factors and epidermal growth factor on mitogenesis and disaccharidase activity in rat (IEC-6) and human (FHs 74 Int) intestinal cells.

Proliferation and differentiation of rat (IEC-6) and human (FHs) small intestinal cells in the presence of epidermal growth factor (EGF), insulin, insulin-like growth factor (IGF)-I, -II, and des[1-3]tripeptide-IGF-I(des-IGF-I) were examined. Thymidine incorporation into IEC-6 cells was significantly increased by insulin, IGF-I, des-IGF-I, IGF-II, and IGF-I+EGF, but not by EGF alone. In contrast, thymidine incorporation into FHs cells was increased only by insulin, IGF-I, and the combination of IGF-I and EGF. Mitogenic activities of IGF-I at 5 nM and insulin at 700 nM (IEC-6) or 1400 nM (FHs) were equivalent, suggesting that both acted through the type I IGF receptor in both cells. IEC-6 cells secreted consistently one predominant IGF binding protein (IGFBP) with M(r) of 28.5 kDa, while FHs cells secreted several IGFBPs with M(r) from 43 to 24 kDa. Mitogenic activity of IGF-I at 5 nM was equal to des-IGF-I at 0.005 nM, indicating that endogenously produced IGFBPs likely inhibit IGF-I action. In IEC-6 cells, IGFBP-2 secretion, but not mRNA expression, was decreased by EGF and IGF-I+EGF treatments, suggesting post-transcriptional regulation. IGF-II and EGF were more potent than IGF-I at increasing maltase and sucrase activities, suggesting that these growth factors may stimulate differentiation to a greater degree than mitogenesis.

Animals↗