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Biomedical subjects

L Logan

Publications and source records attributed to L Logan.

At least 19 recordsLinked to original sources
PubMed2005

Three-dimensional computed tomographic anatomy of the abdominal great vessels pertinent to L4-L5 anterior lumbar interbody fusion.

A recent accumulation of surgical and radiological literature has helped spine surgeons to better understand the anatomy and establish surgical trajectories to the anterior L4-L5 disc space. However, the preoperative display of anatomic data in individual subjects in the three-dimensional (3-D) mode has rarely been attempted. The objective of this study was to acquire 3-D images of the abdominal great vessels pertinent to the L4-L5 anterior lumbar interbody fusion (ALIF), and to better define the radiological vascular anatomy. The 3-D images of 100 subjects with non-spinal diseases, generated from abdominal computed tomography angiography (CTA), were analyzed retrospectively. The anatomy of the great vessels pertinent to the L4-L5 ALIF procedure was investigated by measuring the level of the abdominal aorta (AA) bifurcation and that of the inferior vena cava (IVC) confluence in relation to the lumbar vertebral body. These two complexes were segmented into upper or lower parts, or disc level. The visibility of the middle sacral artery (MSA) and the left L4 lumbar artery on the 3-D images was also assessed. The AA bifurcation level was above L4 in 4, at L4 in 55, at L4-L5 in 23, and at L5 in 18 subjects. The IVC confluence level was at L4 in 17, at L4-L5 in 14, at L5 in 68 and below L5 in 1 subject. Levels of the bifurcation of the AA/IVC as combined data showed that the AA bifurcation was usually located 1 - 2 segments above the IVC confluence. The MSA and L4 segmental artery were identified in 79 and 83 subjects, respectively. The 3-D images of the abdominal great vessels together with the lumbar spinal column were reliably depicted. Anatomic data obtained from this study are in accordance with those obtained from conventional 2-D studies, and the 3-D images can serve as a versatile tool for preoperative evaluation for the ALIF candidates and can contribute to the reduction of surgical time and perioperative vascular complications.

Abdomen↗
PubMed2004

Same day outpatient transjugular liver biopsies in haemophilia.

Patients with haemophilia are at increased risk of hepatitis C infection because of prior transfusion of blood products. Virtually all haemophiliacs who received pooled blood products before the mid-1980s have been infected with hepatitis C. A liver biopsy is important to identify the extent of liver disease, and to help determine the necessity of interferon therapy. With factor replacement, in-hospital liver biopsy is safe. Thirty patients with haemophilia were evaluated for chronic hepatitis C infection. Eleven patients subsequently underwent successful transjugular liver biopsy in the outpatient setting after appropriate factor replacement. Mean +/- SD pre- and posthaemoglobin values were 15.8 +/- 0.79 and 14.4 +/- 0.71 g dL(-1) (P = ns). There was no significant change in heart rate, systolic or diastolic blood pressure during the monitoring period (P = ns) and no major complication was noted in perioperative follow-up. The mean length of the liver biopsy specimens was 1.7 +/- 0.3 cm, mean grade was 2 +/- 0.6 and mean stage was 2.3 +/- 1.2. Our experience demonstrates that outpatient transjugular liver biopsy can be safely performed in patients with haemophilia in the outpatient setting, avoiding the cost and need for hospital admission.

Adult↗
PubMed2004

Black Caribbean adults with HIV in England, Wales, and Northern Ireland: an emerging epidemic?

BACKGROUND: HIV is now well established in the Caribbean, with prevalence in several countries being surpassed only by those of sub-Saharan Africa. Continuing inward migration from the Caribbean and a high incidence of some bacterial STIs among Britain's black Caribbean communities, suggests a considerable potential for HIV spread. METHODS: Data from three national HIV/AIDS surveillance systems were reviewed, providing information on new HIV diagnoses, numbers accessing treatment and care services, and HIV prevalence. RESULTS: Between 1997 and 2001, 528 black Caribbean adults were newly diagnosed with HIV; 62 new diagnoses in 1997, rising to 176 in 2001. Probable heterosexual acquisition accounted for 335 (63%) infections (161 (48%) males, 174 females), and sex between men 171 (32%). Infection was acquired both in the Caribbean and in the United Kingdom. Numbers of black Caribbeans accessing treatment and care services more than doubled between 1997 (294) and 2001 (691). In 2001, 528 (76%) black Caribbeans accessing services were London residents. Among the Caribbean born previously undiagnosed heterosexuals, HIV prevalence was 0.7%; among men who have sex with men (MSM) it was 10.4%. Of those born in the Caribbean, 73% of male heterosexuals, 50% of female heterosexuals, and 65% of MSM who were previously undiagnosed left the clinic unaware of their HIV infection. CONCLUSIONS: Numbers of black Caribbean adults newly diagnosed and accessing treatment and care services in England, Wales, and Northern Ireland increased between 1997 and 2001. Despite a high prevalence of diagnosed bacterial STIs, prevalence among Caribbean born heterosexuals remains low, but it is high among MSM. Surveillance data highlight the need for targeted HIV prevention among black Caribbeans.

Adolescent↗
PubMed2001

The relationship between tracheal width and left bronchial width: Implications for left-sided double-lumen tube selection.

OBJECTIVE: To determine if there is a relationship between tracheal width (TW) and left bronchial width (LBW). DESIGN: Three-dimensional chest computed tomography (CT) scans were used to reconstruct major airways for measurement of TW and LBW. SETTING: Stanford University Medical Center, Stanford, California. PARTICIPANTS: Thirty-one adult patients undergoing chest CT scans. INTERVENTIONS: Cursors were used to directly measure internal diameter from coronal images of the trachea at midclavicular level and the left main bronchus at a level 1 cm below the carina. MEASUREMENTS AND MAIN RESULTS: TW and LBW, but not the LBW-to-TW ratio, were significantly larger in men than in women. The LBW-to-TW ratio was consistent for men (0.75 +/- 0.09) and women (0.77 +/- 0.10). CONCLUSIONS: LBW is proportional to TW. If LBW cannot be measured directly but TW can, the ratio of LBW to TW can be used to predict LBW. An appropriate-sized left double-lumen tube can then be selected for the patient.

Adult↗
PubMed2000

The use of paclitaxel and cisplatin in a patient with epithelial ovarian cancer and human immunodeficiency virus.

OBJECTIVE: Several spots exist of human immunodeficiency virus (HIV)-positive patients developing epithelial ovarian cancer. The optimal chemotherapeutic regimen has been unclear due to potential immunotoxicity from chemotherapy in these already immunocompromised patients. This is the first report of paclitaxel-based combination chemotherapy in an HIV-positive patient with ovarian cancer. METHOD: A 39-year-old woman with HIV was diagnosed with poorly differentiated serous carcinoma. She underwent optimal cytoreductive surgery and received six courses of paclitaxel and cisplatin. RESULTS: The patient experienced a complete clinical response to therapy with no adverse effect on surrogate markers for human immunodeficiency virus (CD4 count, beta2 microglobulin, neopterin, p24 antigen, and viral load). CONCLUSION: Paclitaxel- and platinum-based chemotherapy, the standard of care for adjuvant chemotherapy in advanced ovarian carcinoma, is appropriate therapy for ovarian cancer patients with HIV. There is no evidence that the paclitaxel/cisplatin regimen is associated with progression of HIV or increased chemotherapy-associated morbidity.

Adult↗
PubMed1999

Extraovarian granulosa cell tumor.

OBJECTIVE: The aim of this study was to report a case of extraovarian granulosa cell tumor and to describe its relevance to the histologic origin of granulosa cell tumors and to clinical practice. METHODS: The clinical course and histopathology of the case were reviewed, and a literature search for other reported cases was performed. RESULTS: A 67-year-old woman presented with postmenopausal bleeding and a pelvic mass. Laparotomy revealed a 16-cm mass arising from the right pelvic sidewall, filling the pelvis, and involving the bladder and rectosigmoid colon. Both ovaries appeared normal and were separate from the mass. Pathologic examination revealed granulosa cell tumor. A literature search revealed no recently reported cases of extraovarian granulosa cell tumor. CONCLUSIONS: Granulosa cell tumors can arise in locations other than the ovary and may be derived from the mesenchyme of the genital ridge. Women who have undergone oophorectomy may have the potential to develop granulosa cell tumors.

Aged↗
PubMed1999

Localizing ingested coins with a metal detector.

This study was conducted to determine the utility of metal detection in coin localization by inexperienced operators, and determine the rate of spontaneous passage of asymptomatic esophageal coins. All children who presented to the emergency department of an urban children's hospital with a suspected coin ingestion were eligible. Coin location was predicted from metal detector results, while radiographs confirmed location. Asymptomatic patients with esophageal coins were observed for spontaneous passage. Ninety-one children (ages 9 months to 17 years) were prospectively enrolled. The metal detector had a sensitivity of 98% (53/54) in coin detection and 98% (81/83) in determining coin location as esophageal. Symptoms were poor predictors of coin location. Six of eight asymptomatic patients with esophageal coins spontaneously passed their coins. These results show that metal detection is a good screening test for coin presence and to determine coin location as esophageal. Spontaneous passage of asymptomatic esophageal coins warrants further study.

Adolescent↗
PubMed1999

Computed tomographic angiography: historical perspective and new state-of-the-art using multi detector-row helical computed tomography.

Since its clinical introduction in 1991, volumetric computed tomography scanning using spiral or helical scanners has resulted in a revolution for diagnostic imaging. In addition to new applications for computed tomography, such as computed tomographic angiography and the assessment of patients with renal colic, many routine applications such as the detection of lung and liver lesions have substantially improved. Helical computed tomographic technology has improved over the past eight years with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms, but the greatest advance has been the recent introduction of multi detector-row computed tomography scanners. These scanners provide similar scan quality at a speed gain of 3-6 times greater than single detector-row computed tomography scanners. This has a profound impact on the performance of computed tomography angiography, resulting in greater anatomic coverage, lower iodinated contrast doses, and higher spatial resolution scans than single detector-row systems.

Angiography↗
PubMed1998

Deficiency of the humoral immune response to measles vaccine in infants immunized at age 6 months.

CONTEXT: Measles causes serious morbidity in infants, with the highest risk among those who are 6 to 12 months of age. In the United States, measles vaccine has been given at age 12 to 15 months to minimize interference by passive antibodies and to achieve the high seroprevalence required for herd immunity. Infants of mothers with vaccine-induced immunity may lose passively acquired antibodies before 12 months, leaving them susceptible to measles infection. OBJECTIVE: To assess the immunogenicity of measles vaccine in infants younger than 12 months. DESIGN: Cohort study conducted before and after measles immunization. SETTING: Pediatric clinic in Palo Alto, Calif. PARTICIPANTS: Infants 6 (n = 27), 9 (n = 26), and 12 (n = 34) months of age were enrolled; 72 provided both initial and follow-up samples. MAIN OUTCOME MEASURES: Evaluation of immunogenicity before and 12 weeks after measles vaccination, including measles neutralizing antibody titers, measles-specific T-cell proliferation, and cytokine profiles. RESULTS: Measles neutralizing antibodies were present before vaccination in 52% (12/23), 35% (7/20), and 0% (0/22) of 6-, 9-, and 12-month-old infants, respectively. In the absence of detectable passive antibodies, geometric mean titers after vaccination were significantly lower in 6-month-old infants compared with 9-month-old infants (27 vs 578, P = .01) and 12-month-old infants (27 vs 972, P=.001). The seroconversion rate, defined as a 4-fold rise in antibody titer, in these 6-month-old infants was only 67%, and only 36% of these infants achieved seroprotective neutralizing antibody titers of 120 or higher after vaccination compared with 100% of 9- and 12-month-old infants lacking detectable passive antibody prior to vaccination. T-cell proliferation and cytokine responses to measles did not differ with age. CONCLUSIONS: Humoral immunity was deficient in 6-month-old infants given measles vaccine, even in the absence of detectable passively acquired neutralizing antibodies. Comparison of their responses with those of 9- and 12-month-old infants indicates that a developmental maturation of the immune response to measles may occur during the first year of life, which affects the immunogenicity of measles vaccine.

Age Factors↗
PubMed1998

Preoxygenation before laryngoscopy in children: how long is enough?

The ideal preoxygenation period prior to laryngoscopy in children is unclear. This study was performed to determine an appropriate duration of preoxygenation for infants and children prior to laryngoscopy using endtidal oxygen (FE'O2) criteria. Healthy paediatric patients for elective day surgery procedures were studied. An inflatable mask connected to an oxygen-primed paediatric anaesthesia semiclosed circuit was placed on the face while patients breathed spontaneously during 6.min-1 oxygen flow. An FE'O2 of 0.9 was considered the endpoint, and if not achieved in two min the protocol was ended. Fifty-eight children were studied. Six patients never achieved an FE'O2 of 0.9 and were not considered in the analysis. The times (in seconds with mean +/- SD and range) to achieve a minimum endtidal (FE'O2) of 0.9 for under six months were 36 +/- 11.4(20-50), 7-12 months were 35.5 +/- 13.3(20-60), 13-36 months were 42.6 +/- 18.7(20-90), 37-60 months were 50.8 +/- 18.5(30-90), > 60 months were 68.4 +/- 24.1(30-100). Logistic regression curves were determined for each age group describing the probability of achieving an FE'O2 of 0.9 against time of preoxygenation. All children with satisfactory mask fit were able to preoxygenate to an FE'O2 of 0.9 within 100 s.

Ambulatory Surgical Procedures↗
PubMed1998

Population-based prevalence of symptomatic and asymptomatic astrovirus infection in rural Mayan infants.

Symptomatic and asymptomatic astrovirus infection was prospectively determined in a 3-year birth cohort of Mayan infants. Stool samples from 271 infants and 268 older siblings were tested for astrovirus, adenovirus 40/41, rotavirus and Salmonella, Shigella and Campylobacter species. Concurrent diarrhea, vomiting, fever, or anorexia were noted. Astrovirus was detected in 164 infants (61%) and 20 siblings (7%). Rotavirus (4%) and adenovirus 40/41 (13%) were isolated less frequently. Of all diarrheal episodes reported at a visit, 26% (78/305) were associated with astrovirus; 17% (78/452) of astrovirus infections were associated with diarrhea and 9% with other symptoms. Only diarrhea was associated with astrovirus infection (odds ratio, 1.4; 95% confidence interval [CI], 1.07-1.92; P = .01). Of infants with astrovirus, 70% shed at multiple visits over a period of 2-17 weeks (median, 5). The point prevalence of astrovirus infection was significantly higher among infants than siblings (relative risk, 6.18; 95% CI, 3.93-9.72; P < .0001, chi2). Astrovirus was identified throughout the year, peaked in March and May, and decreased in September. In this population, astrovirus was the most common enteric pathogen isolated; symptomatic infection was prevalent among infants.

Adenoviridae Infections↗
PubMed1997

Host and viral factors affecting the decreased immunogenicity of Sabin type 3 vaccine after administration of trivalent oral polio vaccine to rural Mayan children.

Factors affecting immunogenicity of the first 2 doses of oral poliovirus vaccine (OPV) among unimmunized Mayan infants were prospectively evaluated. The relative impact of multiple variables, including mass or routine vaccination, concurrent enteric bacterial (salmonella, shigella, and campylobacter) and viral (adenovirus 40/41, astrovirus, nonpolio enteroviruses, and rotavirus) infections, interference among Sabin vaccine viruses, and preexisting poliovirus antibodies were studied. Sera were available from 181 infants after 2 OPV doses. Seroresponses were 86% to Sabin type 1, 97% to Sabin type 2, and 61% to Sabin type 3 vaccines. Mass versus routine vaccination and preexisting poliovirus antibodies did not affect immunogenicity. By multiple logistic regression analysis, fecal shedding of homologous Sabin strains was associated with increased seroresponses to all Sabin types, especially to Sabin type 3. Decreased OPV immunogenicity was primarily attributable to interference of Sabin type 3 by Sabin type 2. OPV formulations with higher doses of Sabin type 3 could improve immunogenicity among infants in developing countries.

Antibodies, Viral↗
PubMed1996

College student's blood donation behavior: relationships to demographics, perceived risk, and incentives.

A study was undertaken to empirically investigate whether the student market could be further segmented into blood donor and nondonor markets based on their demographic characteristics, perceived risks, and influence on non-monetary incentives. While significant differences were found between donors and nondonors based on their gender, blood type, student classification, and influence of incentives, no differences were found between the four (physical, psychological, social, or time) dimensions of perceived risk. Discussion focuses on strategies for blood collection agencies for student markets.

Adolescent↗
PubMed1991

Pesticide and polychlorinated biphenyl residues in waters at the mouth of the Grand, Saugeen, and Thames Rivers, Ontario, Canada, 1986-1990.

Water samples were collected from the mouths of the three major agricultural watersheds, the Grand, the Saugeen, and the Thames (Ontario, Canada), between January 1986 and December 1990. Analyses were performed for 18 herbicides, 26 insecticides, and 4 fungicides in use in the basins. A total of between 425 and 474 samples were analyzed for each of the major groups of pesticides. Six herbicides, two insecticides and polychlorinated biphenyls (PCBs) were identified in surface water. Atrazine and its metabolite desethylatrazine were the most frequently found pesticide present in 340 of 474 samples or 72%; the metabolite was not always present with the parent compound. The second most frequently found pesticide was metolachlor which was identified in 30 of 474 samples or 6.3%. 2,4-D and cyanazine were present in 3.3% and 1.5% of the samples, respectively; alachlor, mecoprop, and simazine were present in 0.5% of the samples. Dicamba and metribuzin were present in single samples (0.2%). DDT, heptachlor epoxide, and PCB were identified in only single samples over the 5-year period. Between 342 and 2959 kg/annum of total atrazine were found passing the mouth of the three rivers and entering Lakes Erie or St. Clair between 1986 and 1990. The greatest loss was from the Thames River and the least from the Saugeen River. Between 1% and 2% of that applied in the watershed was lost at the mouth. Loadings of only two other pesticides to the rivers exceeded 5 kg in any one year, namely, metolachlor and 2,4-D. In the case of metolachlor, loadings ranged from less than 5 to 1,726 kg/annum, the highest being in the Thames and the lowest in the Saugeen River. 2,4-D exceeded a loading of 5 kg/annum in 1988 in the Grand River. Atrazine, cyanazine, and metolachlor were tracked across Lake St. Clair from the mouth of the Thames to the mouth of the Detroit River in 1987.

Ontario↗
PubMed1990

Anterior versus posterior walkers: a gait analysis study.

Eight children, who needed walkers to ambulate and who were able to use either anterior or posterior walkers, were selected for a comparative study of both types of walker. Data for gait analysis, using high-speed cinematography, were collected to determine stride length, time in double support and velocity. Trunk, hip and knee angles were also measured during four phases of the gait cycle. The results demonstrated significant improvements in both postural alignment and gait characteristics with the posterior walker.

Cerebral Palsy↗