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Biomedical subjects

L M Robertson

Publications and source records attributed to L M Robertson.

At least 19 recordsLinked to original sources
PubMed2000

Comparison of different methods of intracerebral administration of radioiododeoxyuridine for glioma therapy using a rat model.

The Auger electron emitting agent 5-[125I]iodo-2'-deoxyuridine (i.e. [125I]IUdR) holds promise for the treatment of residual glioma after surgery because this thymidine analogue kills only proliferating cells. However, malignant cells which are not synthesizing DNA during exposure to the radiopharmaceutical will be spared. To determine whether tumour incorporation of [125I]IUdR could be enhanced by protracted administration, we used a C6 cell line, growing in the brains of Wistar rats, as a glioma model and compared three methods of intracerebral delivery of [125I]IUdR. Twenty-four hours after administration of drug, autoradiography of brain sections demonstrated nuclear uptake of the radiopharmaceutical in cells throughout tumour while normal brain cells remained free of radioactivity. The [125I]IUdR labelling indices (% +/- s.e.m.) achieved were 6.2 (0.4) by single injection, 22.5 (4.1) using a sustained release polymer implant (poly(lactide-co-glycolide)) and 34.3 (2.0) by mini-osmotic pump. These results emphasize the need for a sustained delivery system as a prerequisite for effective treatment. These findings are also encouraging for the development of a sustained release system for radiolabelled IUdR for use in the treatment of intracranial tumours, particularly in the immediate postoperative setting.

Animals↗
PubMed1999

Predictors of time to completion of the hepatitis B vaccination series among adolescents.

OBJECTIVES: To determine adolescents' completion rates and factors affecting completion time of hepatitis B (HBV) vaccination. METHODS: Prior to vaccination, participants from a hospital-based and school-based adolescent clinic completed questionnaires assessing sociodemographic variables, family/friend experience with HBV and the vaccine, likelihood of completing the vaccinations, HBV and vaccine knowledge, risk behaviors, chronic illness, and access to clinic. Vaccination times were recorded. RESULTS: Twenty-six months after initiation of the study, 72% of 896 eligible participants had completed the vaccination series. The independent predictors of shorter time to completion were: higher estimated mean household income [odds ratio (OR) = 1.15, 95% confidence interval (CI) = 1.06-1.25), white race (OR = 1.27, 95% CI = 1.01-1.58), female gender (OR = 1.58, 95% CI = 1.31-1.92], and not having smoked cigarettes (OR for smoking in the past 30 days = 0.74, 95% CI = 0.60-0.92). Site of care, risk factors for acquiring HBV, disease and vaccine knowledge, and self-reported desire to complete the series were not associated with completion time. CONCLUSIONS: The primary factors associated with completion of immunization may not be amenable to intervention; mandated strategies for immunization may be more likely to result in protection for adolescents.

Adolescent↗
PubMed1999

Examination of particulate macroporous hydrogels in an extracorporeal rat haemoperfusion model.

A series of macroporous hydrogels has been synthesized, selected from a range of such materials in which the presence of functional groups has been shown to produce sorbent properties with respect to molecules having clinical significance in the field of liver support. The use of freeze thaw polymerization, together with inverse suspension polymerization in hexane, or in brine, enables macroporous beads ranging in size from 150 to 2000 microm, to be prepared from functional monomers exhibiting a range of chemical functionalities and aqueous solubilities. In order to investigate the behaviour of these rigid porous hydrophilic substrates in haemoperfusion, a rat model was used to explore various aspects of whole blood response. The materials were incorporated into an extracorporeal circuit linking the right carotid artery and left jugular vein of male Sprague-Dawley rats. Erythrocyte, leucocyte and platelet levels were monitored over a 240 min haemoperfusion period. The most significant observation is that, apart from the strongly acidic polyacrylic acid substrate. matrix chemistry has relatively little effect on leucocyte or platelet response. The most important factors appear to be surface area, pore size and surface rugosity, which do produce measurable, but not dramatic differences. This is encouraging for future work, since these variables may be manipulated by polymerization conditions.

Acrylates↗
PubMed1999

Serum concentrations of antidepressants and benzodiazepines in nursing infants: A case series.

OBJECTIVE: The relative risk of psychotropic medication use in women with puerperal psychiatric illness who are breastfeeding has yet to be quantified adequately. Although the emotional and medical benefits of breastfeeding and adverse effects of maternal depression on infant development are well described, how these absolute benefits weigh against the potential effects of psychotropic drug use during lactation to ultimately guide clinical decisions is still unclear. The objective of this report was to evaluate the extent that psychotropic medications were present in the serum of infants breastfed by mothers treated with antidepressants and benzodiazepines. DESIGN: Serum samples were obtained from 35 nursing infants whose mothers were treated with psychotropic medications while breastfeeding. When a detectable concentration of medication was reported, information regarding infant behavior was obtained by maternal report. SETTING: The Perinatal and Reproductive Psychiatry Program at Massachusetts General Hospital serves as a regional consultation center for the treatment of psychiatric disorders during pregnancy and the postpartum period. PATIENTS: Subjects were mothers referred to the Perinatal Psychiatry Program for consultation regarding the relative safety of psychotropic medication use while breastfeeding. PRIMARY OUTCOME MEASURES: Presence of detectable levels of medication in infants whose mothers breastfed while taking psychotropic medications during pregnancy and/or during the puerperium and the well-being (based on maternal report) of infants who had detectable serum concentrations of medication. RESULTS: Seventy-four percent (n = 26) of infants had serum medication concentrations below the laboratory limit of detection (assay sensitivity 5-50 ng/mL). In the remaining 26% of the sample (n = 9), serum concentrations of psychotropic medications and/or active metabolites were detected. In each of these cases, infants had been exposed to the medication during pregnancy. Medications were not detected in infant serum when mothers had taken these agents solely during the postpartum period. No readily apparent difficulties with the infants were reported by mothers. CONCLUSIONS: These data support the low incidence of infant toxicity and adverse effects associated with antidepressant and benzodiazepine use during breastfeeding. These data also suggest that infant serum monitoring is helpful in the assessment of medication exposure in children of mothers who breastfeed while using psychotropic medications. Given the limited accumulated data regarding serum concentrations of psychotropic medications in breastfeeding infants, no single agent seems to be safer than another. Therefore, choice of pharmacologic treatment should be guided by the likelihood that it will result in restoration of maternal psychiatric well-being.

Antidepressive Agents↗
PubMed1998

Knowledge of health insurance coverage by adolescents and young adults attending a hospital-based clinic.

PURPOSE: To describe adolescents' and young adults' knowledge about their health insurance, and to identify factors associated with correct knowledge of health insurance in this population. METHODS: Data were analyzed from a confidential questionnaire administered to 830 patients at a hospital-based adolescent medicine clinic. The questionnaire contained items pertaining to insurance type, demographics, health status, and health-risk behaviors. Actual health insurance data and information regarding utilization of health services were obtained from the hospital billing data-base. Predictors of health insurance knowledge were determined through bivariate analyses followed by stepwise logistic regression. RESULTS: A total of 50.7% of respondents correctly identified their type of health insurance. Those who correctly identified their insurance had a higher mean age. Only 48.5% of participants who were 11-18 years old could identify their insurance type, versus 53.1% of 19-21-year-olds and 64.7% of 22-24-year-olds (p = 0.02). Sixty-five percent of Medicaid patients and 76.3% of hospital free care patients knew how their medical bills were paid, versus 17.9% of self-pay patients and 47.3% of patients with private insurance (p < 0.01). Greater utilization of health services was associated with increased rates of insurance knowledge among 19-24-year-olds on bivariate analysis; however, this factor was not significant when controlling for other factors. Regression analysis revealed that older age and insurance type other than self-payment were independent predictors of health insurance knowledge in adolescents (11-18 years old), while female gender and insurance type other than self-payment were independent predictors of insurance knowledge in young adults (19-24 years old). CONCLUSIONS: Approximately half of adolescents and young adults do not know how their medical bills are paid. Validation of self-reported insurance data is, therefore, critical both in clinical practice and health services research.

Adolescent↗
PubMed1997

Low prevalence of antibody to hepatitis C virus in an urban adolescent population.

We tested 869 subjects attending either an urban adolescent medicine clinic or a school-based clinic for antibody to hepatitis C virus. Demographic data indicated a representative study sample, and behaviors associated with hepatitis C virus transmission. One subject (0.1%) was seropositive for antibody to hepatitis C virus, indicating a very low prevalence of hepatitis C virus exposure in adolescents.

Adolescent↗
PubMed1997

Use of hormonal methods of birth control among sexually active adolescent girls.

OBJECTIVE: To identify factors associated with the use of various birth control methods among sexually active adolescent girls. DESIGN: A survey distributed as part of a larger study measuring compliance with hepatitis B vaccination. SETTING: A hospital-based and a school-based clinic. MEASURES: Demographic and health behavior data including sexual activity, contraceptive method, substance use, condom use, and history of sexually transmitted diseases (STDs) were collected. Birth control method was confirmed by medical record review. Associations with the outcome variable of birth control method were analyzed using chi square, Kruskal-Wallis analyses of variance, and t-tests, followed by logistic regression analysis. RESULTS: Among sexually experienced girls, 39% (n = 123) reported using oral contraceptive pills (OCPs), 5.4% (n = 17) used Depo-Provera (medroxyprogesterone acetate) or Norplant (levonorgestrel), and 55.6% (n = 175) used no hormonal method. Logistic regression analysis revealed that the factors most significantly associated with the use of hormonal methods were older age (odds ratio [OR] = 1.19; 95% confidence interval [CI], 1.07-1.33), not using a condom at last intercourse (OR = 0.55; CI, 0.34-0.90), and having had a well visit within 1 year (OR = 2.11; CI, 1.12-3.70). OCP users were less likely than Depo-Provera or Norplant users to have used alcohol (p = 0.041), cigarettes (p = 0.002), or marijuana (p = 0.018) in the past 30 days. OCP users were less likely than nonusers of hormonal methods to have smoked cigarettes (p = 0.034) or marijuana (p = 0.052). The school-based clinic had a greater proportion of subjects using long-acting progestins (p < 0.001). CONCLUSIONS: The decreased rate of condom use among those who used hormonal birth control methods and the different rates of health risk behaviors among users of various methods require targeted counseling efforts to decrease pregnancy and STD rates among young women.

Adolescent↗
PubMed1997

Does swimming decrease the incidence of otitis media?

To determine the influence of swimming on the incidence of otitis media in children, the authors designed a case control survey involving 32 children, aged 1 to 4 years, who were participating in swimming classes. Thirty control subjects were matched for age, race, and sex. The participants were pooled from the general pediatrics clinic and toddler swimming classes in Nassau County, New York. Parents completed a questionnaire gathering data over a 12-week study period during the winter months. Information was gathered regarding demographics, number of ear infections, history and frequency of swimming during the study period, presence of head submersion, day care center attendance, allergies, chronic medical conditions, otolaryngology consultations, ear surgery, and air travel. Forty-three percent of nonswimmers compared with 19% of swimmers had one or more ear infections during the study period (P < .02). The remaining factors surveyed did not differ significantly between groups. A review of the literature yielded two studies suggesting that swimming may have a beneficial effect on eustachian tube function and may indirectly decrease the occurrence of otitis media. Based on these findings, the authors conclude that there appears to be no basis to the commonly held belief that swimming may induce or exacerbate otitis media. In fact, the converse may be true.

Case-Control Studies↗
PubMed1996

Course of panic disorder during pregnancy and the puerperium: a preliminary study.

Pregnancy has been referred to as a time of well-being for patients with psychiatric disorder. However, this impression is derived primarily from anecdotal reports and retrospective studies, rather than systematic prospective evaluation. In this study, 10 pregnant women with previous histories of panic disorder were evaluated prospectively across pregnancy and the postpartum period using the Structured Clinical Interview for DSM-III-R and the Clinical Global Impression. Information regarding pharmacotherapy received was also recorded. Seven of 10 subjects continued to meet DSM-III-R criteria for panic disorder at all trimester visits. Symptoms persisted for some patients even in the context of treatment with antipanic medications. Most subjects (n = 9) met DSM-III-R criteria at 1-3 months postpartum despite nearly uniform intensification of antipanic treatment. Although some women may experience diminished symptoms of panic during pregnancy, in this sample most continued to experience panic attacks and to require antipanic treatment to control symptoms.

Adult↗
PubMed1995

Prophylactic estrogen in recurrent postpartum affective disorder.

Seven women with histories of puerperal psychosis and four with histories of puerperal major depression were consecutively treated with high-dose oral estrogen immediately following delivery. None of the women had histories of nonpuerperal affective disorder, and all women were affectively well throughout the current pregnancy and at delivery. Despite the high risk for recurrent illness in this population, only one woman developed relapse of postpartum affective disorder. All others remained entirely well and required no treatment with psychotropic medications during the 1 year follow-up period. This low rate of relapse, 9% compared to an expected 35-60% without prophylaxis, suggests that oral estrogen may stem the rapid rate of change in estrogen following delivery, thereby preventing the potential impact on dopaminergic and serotonergic neuroreceptors. It is hypothesized that the rapid rate of change of estrogen after delivery creates an "estrogen withdrawal state." This may be a critical factor in driving acute puerperal affective psychosis and early-onset puerperal major depression.

Administration, Oral↗
PubMed1995

Regulation of c-fos expression in transgenic mice requires multiple interdependent transcription control elements.

Transcription control regions of eukaryotic genes contain multiple sequence elements proposed to function independently to regulate transcription. We developed transgenic mice carrying fos-lacZ fusion genes with clustered point mutations in each of several distinct regulatory sequences: the sis-inducible element, the serum response element, the fos AP-1 site, and the calcium/cAMP response element. Analysis of Fos-lacZ expression in the CNS and in cultured cells demonstrated that all of the regulatory elements tested were required in concert for tissue- and stimulus-specific regulation of the c-fos promoter. This implies that the regulation of c-fos expression requires the concerted action of multiple control elements that direct the assembly of an interdependent transcription complex.

Animals↗
PubMed1995

Postpartum prophylaxis for women with bipolar disorder.

OBJECTIVE: The postpartum period has typically been considered a time of heightened vulnerability for development of affective disorders, and women with bipolar disorder have consistently demonstrated vulnerability to puerperal worsening of mood. This retrospective study examined the extent to which mood-stabilizing agents provide prophylactic benefit to bipolar women during the postpartum period. METHOD: The clinical course of 27 women meeting the DSM-III-R criteria for bipolar disorder was followed during pregnancy and the postpartum period. Information regarding severity of illness (as measured by number of episodes of mania, depression, or both) was obtained, in addition to data on pharmacotherapy (if any) received before, during, and after pregnancy. The extent to which the prophylactic use of antimanic agents minimized the risk of relapse was explored. RESULTS: Only one of the 14 patients taking prophylactic agents during the acute puerperium relapsed within the first 3 months postpartum, while eight of the 13 who did not receive antimanic drugs showed evidence of recurrent affective instability during those 3 months. A survival analysis indicated that the women receiving prophylactic treatment with mood stabilizers maintained well-being significantly longer than the women who did not receive such treatment. CONCLUSIONS: Women with bipolar disorder appear to benefit from puerperal prophylaxis with mood stabilizers. Consistent with results of earlier studies, postpartum prophylaxis was associated with lower rates of relapse into affective disorders. The findings have implications for the early identification and treatment of subgroups of women at particular risk for puerperal illness.

Adult↗
PubMed1995

[Pseudohypoparathyroidism].

A 5 year old boy with normal phenotype and normal renal function presented tetany. Hypocalcemia and hyperphosphatemia, with increased serum levels of parathyroid hormone (PTH) were detected in serial measurements. Pseudohypoparathyroidism was diagnosed. This disease presents the biochemical abnormalities of hypoparathyroidism (hypocalcemia, hyperphosphatemia) with peripheral resistance to PTH activity. The patient was treated effectively with calcium and vitamin D supplements. The causes of hypocalcemia related to parathyroid gland activity are reviewed and the physiopathology of pseudohypoparathyroidism is described.

Alkaline Phosphatase↗
PubMed1993

Continuous c-fos expression precedes programmed cell death in vivo.

The development of a multicellular organism involves a delicate balance among the processes of proliferation, differentiation and death. Naturally occurring cell death aids tissue remodelling, eliminates supernumerary cell populations and provides structural elements such as hair and skin. In the nervous system, selective cell death contributes to the formation and organization of the spinal cord and sympathetic ganglia, retina and corpus callosum. But cell death also occurs in several neuropathological conditions, such as amyelotrophic lateral sclerosis and Alzheimer's disease. Therefore an elucidation of the mechanisms responsible for cell death is critical for an appreciation of both normal development and neuropathological disorders. Using a fos-lacZ transgenic mouse, we provide evidence showing that the continuous expression of Fos, beginning hours or days before the morphological demise of the cell, appears to be a hallmark of terminal differentiation and a harbinger of death.

3T3 Cells↗
PubMed1993

Characterization of the UL10 gene product of herpes simplex virus type 1 and investigation of its role in vivo.

On the basis of predicted amino acid sequence characteristics, herpes simplex virus type 1 gene UL10 is thought likely to encode a membrane protein with eight potential transmembrane regions. Previously, a protein with an apparent M(r) 47,000 on SDS-PAGE was identified as a product of this gene. Here we have further characterized this protein, and show that it is modified by N-linked glycosylation, associates with membranes from infected cells, and is a component of the virus particle. It is not essential for virus growth in tissue culture. To investigate its role in vivo a deletion mutant lacking the majority of the UL10 open reading frame was constructed (UL10-del). The in vitro growth properties of this virus were consistent with previous studies; it grew to give slightly lower yields than wild-type and revertant viruses, and had no apparent temperature-sensitive or host range phenotype. In vivo, in a mouse model, UL10-del was capable of establishing a latent infection, although it was impaired for growth at the periphery, and for spread to and/or growth within the nervous system relative to wild-type or revertant viruses.

Animals↗
PubMed1993

Biomaterials in medicine--a bioengineering perspective.

Biomaterials are considered with an emphasis on those used in artificial organs. Attention is drawn to the importance of the polymeric biomaterials and factors which affect their properties. Functions of membranes, sorbents, blood tubing, ventricular diaphragms and cell culture substrates are examined in order to obtain a summary of fundamental properties. Observations are made on the importance of blood compatibility assessment and its association with a biomaterial structure-property relationship. Blood-biomaterial interactions are discussed in terms of an overall relationship between the three components--blood, biomaterial and antithrombotic agent, with examples given of factors influencing each component. Cell-biomaterial interactions are examined in the areas of toxicity evaluation and the promotion of cell attachment and growth, where an overall relationship is described for the cell, growth medium and growth factors, and the biomaterial acting as a substrate.

Animals↗