Biomedical subjects

L Harris

Publications and source records attributed to L Harris.

At least 91 records · Page 5Linked to original sources

PubMed1994

DDI pacing: indications, expectations, and follow-up.

The DDI mode of pacing that permits noncompetitive atrioventricular sequential bradycardia support was chosen in 65 of 480 (14%) patients selected for dual chamber pacing between February 1985 and March 1990. All patients were implanted with Pacesetter 283 or 285 pulse generators and programmed to DDI. The indications for pacing were sick sinus syndrome (n = 52), combined sinus node dysfunction and AV block (n = 13). Forty-two of these patients had a history of paroxysmal atrial arrhythmias. All patients received passive fixation atrial and ventricular leads. Follow-up thereafter was performed predischarge, and at 6 weeks, 3 and 6 months after discharge. The duration of follow-up ranged from 1-61 months (mean 31 months). Fifty-four of 65 (83%) patients chosen for DDI remain programmed in the DDI mode. Three patients were reprogrammed to VVI and eight to DDD. During the course of follow-up, six patients presented with effective VVI pacing with consistent ventriculoatrial conduction that was appropriately sensed by the atrial circuit with atrial output inhibition. A further four patients presented with "functional undersensing" due to ventricular blanking period (VBP) characteristics in these pulse generators and in this mode. Functional undersensing was eliminated in all but one patient by reprogramming the VBP to 13 msec with no subsequent episodes of provoked crosstalk inhibition. Effective VVI pacing was observed in patients with AV block during times of sinus acceleration.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1994

Hypocrellin, from Hypocrella bambuase, is phototoxic to human immunodeficiency virus.

Hypocrellin, a photodynamic perylene quinonoid isolated from the Chinese medicinal fungus Hypocrella bambuase, was evaluated for antiviral activity against the human immunodeficiency virus (HIV-1). Hypocrellin was phototoxic to HIV-1, almost as good as the structurally similar plant pigment hypericin, and like hypericin its activity required visible light. In contrast peroxyhypocrellin had little or no effect on the virus.

3T3 Cells↗

PubMed1994

Photoactive terthiophenes: the influence of serum on anti-HIV (human immunodeficiency virus) activities.

A number of carboxylic acid derivatives of the photoactive terthiophene, alpha-terthienyl, were found to possess impressive UVA-dependent activity against the human immunodeficiency virus, HIV-1; but only when assayed in the absence of serum, indicating that the latter contained interfering components. Good antiviral activity required a high rate of singlet oxygen production, in accordance with previous observations on thiophenes.

Antiviral Agents↗

PubMed1994

Fetal lateral ventricles: reassessment of normal values for atrial diameter at US.

PURPOSE: To assess the normal range of cerebral ventricular atrial diameters during the second and third trimesters of pregnancy. MATERIALS AND METHODS: The transverse diameter of the atrium of the lateral ventricle was prospectively measured in 739 consecutive antenatal ultrasound examinations by positioning electronic calipers on the luminal margins of the ventricular wall, perpendicular to the long axis of the ventricle. RESULTS: The mean ventricular atrial diameter for the combined group of all 739 studies was 5.4 mm +/- 1.2 (standard deviation). The transverse diameter of the ventricular atrium did not progressively increase with advancing gestational age. All fetuses younger than 17 menstrual weeks had ventricular atrial diameters less than 8 mm. Four fetuses had ventricular diameters of 10 mm or greater. CONCLUSION: A reasonable upper limit of normal for transverse atrial diameter for gestational age of 25 weeks and above appears to be 10 mm. Prior to 25 weeks, diameters over 8 mm are unusual in the healthy fetus and signal the need for a detailed evaluation of fetal anatomy.

Cerebral Ventricles↗

PubMed1994

Disordered eating among adolescents whose parents misuse alcohol: protective and risk factors.

Studies show that children of alcoholics constitute an at-risk population. This study attempted to understand the impact of parental alcohol misuse on the disordered eating behaviors of children, based on a sample of 838 teenagers from alcohol-misusing parents in Minnesota. These teenagers had significantly higher prevalence rates of all the seven eating disordered symptoms that were studied. The study also identified a few protective factors: those who did not develop any of the disordered eating symptoms were more satisfied with their present weight and proud of their body. Further, they had less worry of being sexually abused and perceived that their schools were relatively alcohol-free.

Adolescent↗

PubMed1994

Sotalol in patients with implanted automatic defibrillators: effects on defibrillation and comparison with amiodarone.

OBJECTIVES: Although many patients receiving implanted cardioverter defibrillators receive concomitant antiarrhythmic therapy, the risks and benefits of different agents for such patients are not well understood. It was hypothesized that sotalol, a drug with beta-blocking and class II antiarrhythmic properties would be useful in these patients. DESIGN: Nonrandomized prospective cohort study of the effects of sotalol versus other antiarrhythmic therapy on defibrillation energy requirements. SETTING: Tertiary care referral centre. PATIENTS: Patients referred for management of life threatening ventricular arrhythmia in whom an implanted cardioverter defibrillator was indicated on standard clinical grounds. INTERVENTIONS: Intraoperative testing of defibrillation energy requirements, exercise testing, electrophysiological testing. MAIN RESULTS: Fifteen patients were treated with oral sotalol (173.3 +/- 59.8 mg/day). Sotalol blunted maximal heart rate during treadmill exercise (120.9 +/- 29.9 beats/min). Mean right ventricular effective refractory period increased from 251.7 +/- 21.7 to 276.7 +/- 25.7 ms (P = 0.05). All patients received one large (28 cm2) and one small (14 cm2) epicardial electrode patch. The lowest energy to defibrillate successfully from induced ventricular fibrillation (VF) was 5.9 +/- 3.7 J (median 4.1 J), with all patients defibrillated at 15 J or less. In a concurrent comparison group of 16 similar patients not treated with sotalol (13 on amiodarone and three on beta-blockers), with identical or larger patch size, and identical placement, the lowest successful energy to defibrillate from induced VF was significantly higher (16 +/- 8.8 J) (P < 0.05). Mean cycle length of VF from intracardiac recordings was 232 +/- 37 ms, and was significantly inversely correlated with lowest successful energy (r = 0.61, P < 0.05). CONCLUSIONS: Oral sotalol may be useful in conjunction with an automatic defibrillator; it is associated with low defibrillation energy requirements in humans, and may alter VF.

Administration, Oral↗

PubMed1993

Time until institutionalization and death in patients with dementia. Role of caregiver training and risk factors.

OBJECTIVE: To determine which variables best predict prognosis--time to nursing home admission (NHA) and death--in patients with dementia. DESIGN: Survival analysis employing the Cox proportional hazards model with the use of risk variables pertaining to dementia severity and its rate of progression and caregiver functioning. SETTING: Patients and their caregivers participating in a controlled intervention study of training for caregivers in home management of dementia. PARTICIPANTS: Patients with mild Diagnostic and Statistical Manual of Mental Disorders, Third Edition--defined dementia (N = 91; 68 patients with Alzheimer-type dementia, 20 with vascular dementia, and three with other types) and their caregivers. FOLLOW-UP: All subjects had repeated assessments in the first year to determine rates of change and thereafter annually to determine the date of NHA and/or death. RISK VARIABLES: (1) Caregiver training; (2) dementia severity at index assessment; (3) caregiver stress, neuroticism, and socialization; (4) changes in patients and caregivers during the first 12 months; and (5) patient characteristics. RESULTS: By 5 years' follow-up, 76% of patients had entered a nursing home and 42% had died. Dementia severity and rate of deterioration ("how far" and "how fast") and caregiver psychological morbidity significantly influenced rates of NHA and death. Training of caregivers was significantly associated with delayed NHA and reduced mortality. Greater patient age, non-Alzheimer's dementia, and, unexpectedly, greater caregiver psychological morbidity were associated with shorter survival to death. CONCLUSIONS: Both severity ("how far") and rate of deterioration ("how fast") influence time to NHA and death. Caregiver training may have important ameliorating effects on the prognosis of dementia.

Aged↗

PubMed1993

Phospholipase inhibition and the electrophysiology of acute ischemia: studies with amiodarone.

Previous studies have shown a close temporal relationship between lipid abnormalities and membrane dysfunction in ischemia and that phospholipase-inhibiting drugs limit such derangements. Amiodarone is a potent phospholipase inhibitor, but its potential or that of any other inhibitor to simultaneously attenuate lipid abnormalities and electrophysiological changes in the very early phase of ischemia has never been studied. We therefore investigated simultaneously such changes in early ischemia. In isolated porcine hearts perfused with or without pure amiodarone solutions, electrophysiologic changes before and during 20 min of LAD occlusion were recorded using unipolar electrodes and Franz contact electrode catheters, and full thickness myocardial biopsies obtained for lipid analyses. In untreated hearts (n = 5), occlusion of LAD resulted in the rapid onset of TQ depression/ST elevation within 1 min and plateauing at 10 min. There were mean increases of 33% and 50% in lysophosphatidylcholine and 33% and 70% in lysophosphatidylethanolamine levels at 5-7 min and 20 min of ischemia, respectively. Non-esterified fatty acid (NEFA) content did not change significantly during the first 5-7 min, but increased by 75% after 20 min of LAD occlusion. In treated hearts (n = 5) there was a 37% increase in sinus cycle length after amiodarone administration (503 +/- 85 vs 689 +/- 115 ms, P < 0.01) but no significant change in ventricular effective refractory period (202 +/- 22 vs 204 +/- 21 ms), action potential duration (215 +/- 11 vs 217 +/- 7 ms), or amplitude (31 +/- 6 vs 28 +/- 3 mV) was observed. Also, amiodarone treatment did not alter total phospholipid content, lysophospholipids and NEFA levels of non-ischemic hearts. However, there was significant attenuation (P < 0.01) of the onset of the TQ/ST shift and preservation of action potential amplitude (P < 0.02) during the first 5-7 min of LAD occlusion with concomitant suppression of the increase in both lysophospholipids (hydrolysis products of membrane phospholipids by endogenous phospholipases) and NEFA levels observed after 5-7 and 20 min of ischemia. The results suggest that amiodarone can delay the onset and limit the extent of electrophysiologic change in early myocardial ischemia in temporal association with suppression of myocardial phospholipase activities.

Action Potentials↗

PubMed1993

The importance of light in the anti-HIV effect of hypericin.

The requirement for light in the anti-HIV-1 activity of hypericin was investigated. The hypericin concentration-dependence and light dosage-dependence of the reaction were measured. Under conditions in which hypericin caused substantial inactivation of HIV-1, there was a strict requirement for visible light. Only when the concentration of hypericin approached the cytotoxic level was there an apparent light-independent antiviral effect. This strict light-requirement for the antiviral effect could explain some of the apparently discrepant results reported by other workers. Furthermore if hypericin is contemplated for use in humans, the importance of light must be considered.

Anthracenes↗

PubMed1993

The anti-HIV activity of the phytochemical alpha-terthienyl.

The plant trithiophene, alpha-terthienyl (alpha T), was evaluated for activity against the human immunodeficiency virus (HIV-1). Antiviral activity specifically required long wavelength light (UVA, 320-400 nm). The compound had little or no activity in visible light or in the dark. The anti-HIV effect was UVA-dose dependent and was proportional to the concentration of alpha T, according to several parameters of virus infectivity and replication. The efficacy was decreased to some extent by the presence of bovine serum in the reactions; but under optimal conditions 0.1 microgram/ml. alpha T (3 x 10(-7) M) could inactivate 10(4)-10(5) infectious particles. In contrast poliovirus and Coxsackievirus infectivity were relatively resistant to alpha T + UVA.

Blood↗

PubMed1993

Lexical and prosodic cues in the comprehension of relative certainty.

This study examined the development of children's comprehension of the use of intonation and belief verbs to mark the relative certainty with which a speaker makes a statement. Subjects were presented with a task in which they had to guess the location of an object hidden in one of two boxes over a series of trials. As clues to location, the children were presented with contrasting pairs of statements by two puppets. In the first experiment with 30 children at each of three, four, five and six years of age, statements in each pair differed either with respect to the belief term included - know, think or guess - or with respect to terminal pitch contour - rising or falling. Results showed that three-year-olds did not use any information reliably to determine the location of the object, four-year-olds treated falling pitch as a more reliable indicator of location than rising pitch, and older children responded on the basis of the belief terms but not on the basis of prosody. In Experiment 2, 40 children at each of three, four and five years heard statements which differed with respect to both belief verbs and prosody. In one condition falling intonation was paired with the more certain belief term in each pair, and rising intonation with the less certain pair. In a second condition, the pairings were reversed. Results showed that, while four-year-olds could tell the difference between know and think, they could not use intonation information to determine the location. Five-year-olds used both lexical and prosodic information, with prosodic cues modulating the effects of lexical. Taken together, these experiments show that prosodic and lexical cues start to be used by children to interpret relative speaker certainty at about the same time developmentally, but that lexical cues initially appear to dominate while prosodic ones modulate their effects. Finally, it is argued that children's understanding of prosody will be best revealed in contexts in which they are required to respond to the pragmatic function of verbal stimuli rather than to the lexical content.

Age Factors↗

PubMed1993

Lessons from a mood disorders unit.

Specialist treatment centres, such as the Mood Disorders Unit (MDU) at Prince Henry Hospital, Sydney, have developed in response to the high prevalence of mood disorders and their frequent persistence and treatment resistance. The MDU's assessment and treatment of patients from a state-wide catchment area and its teaching and research effectiveness are reviewed. Of 479 patients assessed between 1985 and 1989, there were 304 with primary depressive disorders, of whom 154 were followed up by clinical assessment at 52 weeks and 231 by telephone interview at 3 1/2 years. At intake, 59% were tertiary referral patients and 88% were from outside the local area. Two-thirds were recovered 3 1/2 years later, despite the disorders having been generally severe and protracted. Treatment modality was associated primarily with diagnosis, but also with age and somewhat with the patient's personality and consultant psychiatrists' preferences. No consistent predictors of outcome were discerned. Specialist tertiary referral centres, such as the MDU, contribute significantly to treatment success, especially of difficult cases, and enrich teaching and research.

Adjustment Disorders↗

PubMed1993

The unusual UVA-dependent antiviral properties of the furoisocoumarin, coriandrin.

The novel furoisocoumarin, coriandrin, which was found recently to possess an interesting combination of photobiological properties, was investigated for antiviral activity in the presence and absence of UVA (long-wavelength ultraviolet radiation). In contrast to results obtained with other antiviral furocoumarins, such as 8-MOP (8-methoxypsoralen), coriandrin was much more phototoxic to the RNA-virus Sindbis virus than to the DNA-virus murine cytomegalovirus, although both viruses were substantially more sensitive to this compound than they were to 8-MOP. Human immunodeficiency virus, HIV-1, was also susceptible to coriandrin + UVA. Another unexpected finding was that viruses without membranes were completely resistant to coriandrin. This suggests that a membrane component was a target for the compound. The antiviral activity of coriadrin was profoundly inhibited by serum components in the reaction mixtures, which suggests that the compound may have a strong affinity for certain protein or lipid materials, although maximal interference was only obtained when all components of the reaction mixture, virus, coriandrin and serum, were irradiated simultaneously. Thus it appears that coriandrin has unusual antiviral properties that would not be predicted from its chemical similarity to furocoumarins.

3T3 Cells↗

PubMed1993

Light-mediated activities of thiarubrines against human immunodeficiency virus.

Two thiarubrines (dithiacyclohexadienes), which were isolated recently from species of Asteraceae, were investigated for light-mediated antiviral activity against human immunodeficiency virus (HIV-1). Both compounds (thiarubrines A and D) showed good anti-HIV activity, in micromolar concentrations, which was dependent upon UVA radiation. They showed no anti-viral activity in the dark, and only weak visible light-mediated activity, despite the significant absorbance of these compounds in the 480 nm region. The resulting inactivated virus was unable to replicate in cell cultures, as indicated by loss of cytopathogenicity, the absence of cells expressing HIV-1 antigens and lack of production of HIV-1 p24 protein. Although this antiviral activity was not as efficient as that shown by the photoactive plant thiophene, alpha-terthienyl, both thiarubrines demonstrated increased activity when the serum component of the virus stock was reduced. This suggested that a component of bovine serum interfered to some extent with the anti-HIV activity.

Alkynes↗

PubMed1993

The anti-HIV activities of photoactive terthiophenes.

Various synthetic analogues of the naturally occurring terthiophene, alpha-terthienyl (alpha T), were evaluated for anti-human immunodeficiency virus (HIV) activity. The compounds were incubated individually with a known amount of the virus, with or without UVA radiation (long-wavelength ultraviolet) and residual virus was monitored for its ability to produce cytopathic effects in cell culture and the production of virus-specific protein (p24). The basic terthiophene structure was essential for good anti-HIV activity, although various side chains, such as alcohols, bromo, methyl, thiomethyl and trimethylsilyl groups, permitted retention of maximum activity. Under optimum conditions, as little as 12 ng/mL of these compounds (i.e. approximately 3 x 10(-8) M) could inactivate 10(3) infectious virions. None of the compounds however were more active than alpha T itself. In all cases, UVA radiation was essential. Several side chains decreased the antiviral efficacy, and some side chains abrogated the activity.

Antiviral Agents↗

PubMed1993

Persistent mild hip deformation in preterm infants.

Preterm infants often develop a postural deformation of the legs with wide hip abduction and external rotation giving a 'frog leg' posture. It has been shown that the deformation persists at the age of 3-4.5 years and the use of postural techniques aimed at reducing the deformation is recommended.

Child, Preschool↗

PubMed1993

Prognosis of depression in the elderly. A comparison with younger patients.

The prognosis of depression in the elderly was investigated in a mixed-age sample of 242 consecutive referrals, with DSM-III defined unipolar major depressive episode, to a specialist unit for mood disorders. Subjects were followed up at about 1 and 3.8 years. There was no significant difference in outcome between younger (under 40 years), middle aged (40-59 years) and older (60 years or more) depressed patients. For the 61 elderly subjects with depression, prognosis improved with time, with 25% having a lasting recovery at the first and 41% at the second follow-up. Early onset, recurrence, and poor premorbid personality were associated with a worse prognosis. Three (5%) elderly depressives had committed suicide and seven (11%) had died from natural causes by the second follow-up. Despite some methodological limitations, our findings suggest a more optimistic outlook and the need for longer, more assertive treatment for elderly, depressed patients.

Adolescent↗

PubMed1993

Traumatic cysts of the spleen--the role of cystectomy and splenic preservation: experience with seven consecutive patients.

Nonparasitic secondary cysts (pseudocysts) of the spleen are uncommon and usually result from blunt abdominal trauma. A 3-year experience with 7 consecutive cases of posttraumatic splenic pseudocysts suggests an increased prevalence of this clinical entity. This report describes 7 adult patients (5 men and 2 women) with a mean age of 32 years, all of whom sustained relatively minor trauma within 5 years of admission. Persistent epigastric or left upper quadrant pain led to a CT scan diagnosis of splenic cysts that varied in size from 7 cm to 15 cm. Each patient underwent resection of the cyst-bearing portion of the spleen with preservation of the remaining normal splenic parenchyma. There were no deaths or complications in the entire group. Because posttraumatic splenic cysts are rare, the accumulation of a significant data base leading to firm conclusions is lacking.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗