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Biomedical subjects

F Khan

Publications and source records attributed to F Khan.

230 records · Page 13Linked to original sources
PubMedDate not supplied

Blood flow changes in diabetic foot ulcers treated with dermal replacement therapy.

The study investigated whether the effects of dermal replacement therapy on wound healing are associated with an increase in blood flow at the base of diabetic foot ulcers treated with Dermagraft. Seven full-thickness ulcers were assessed in five patients with type 2 diabetes mellitus and peripheral neuropathy. All lesions had been present for at least 3 months with no recent change in size, despite routine foot care and protective dressings. Dermal replacement therapy was applied weekly to the base of each wound for 8 weeks, after which regular dressing was resumed. Microvascular blood flow was assessed using laser Doppler imaging immediately before and after 2, 5, and 8 weeks of treatment. Blood flow increased by an average of 72% in the base of five out of the seven ulcers studied. Five of the lesions healed by 12 weeks and the other two reduced in size by approximately 25%. The changes in blood flow observed in this pilot study might reflect angiogenesis in the newly formed granulation tissue and/or vasodilatation of existing vessels, processes that are possibly enhanced by the intervention.

Aged↗
PubMedDate not supplied

Skin blood flow changes in response to intradermal injection of bupivacaine and levobupivacaine, assessed by laser Doppler imaging.

BACKGROUND AND OBJECTIVES: The vascular effects of local anesthetics are important determinants of their therapeutic activity. Drugs that vasoconstrict have the potential clinical advantages of limited systemic uptake and prolonged duration of effect. The aim of this study was to assess quantitatively the cutaneous vasoactivity of racemic bupivacaine and one of its enantiomers, levobupivacaine. METHODS: Four concentrations of each drug (0.1 mL each of 0.125%, 0.25%, 0.5%, and 0.75%), as well as normal saline, were injected intradermally into randomly assigned sites on the forearms of 10 volunteers. We measured skin blood perfusion using laser Doppler imaging before injection and at 2.5, 10, 20, 40, 60, and 90 minutes thereafter. RESULTS: Both drugs produced a rapid, dose-dependent increase in skin perfusion (P <.001). Saline also caused an increase in perfusion, although less sustained. By 40 minutes, most responses had returned to baseline levels. However, after this time, perfusion continued to decrease, below baseline, for both bupivacaine and levobupivacaine. The exception to this was 0.75% bupivacaine, the response to which was significantly higher than the same concentration of levobupivacaine over this later period (P <.05). CONCLUSIONS: Bupivacaine and levobupivacaine both have a biphasic effect on skin microvessels. The vasoconstriction observed after 40 minutes may occur when the quantity of drug remaining at the administration site has decreased to a lower level. The continued vasodilatation caused by bupivacaine is more difficult to interpret. The results suggest that these local anesthetics cause vasodilatation at high doses and vasoconstriction at lower, subclinical doses. This hypothesis and the clinical relevance of these effects warrant further investigation.

Administration, Cutaneous↗
PubMedDate not supplied

Blood lead levels in children in south central Los Angeles.

We retrospectively reviewed 3 679 pediatric records from King/Drew Medical Center, south central Los Angeles, between 1991 and 1994. Blood lead levels of children were followed to age 18 y. Patients were not referred specifically for lead poisoning. The sample was primarily Latino. Geometric mean blood lead peaked at 6.7 micrograms/dl (0.32 mumol/l) between 2 and 3 y of age. There was a downward secular trend and a seasonal trend. Males had higher lead levels than females. Children who lived in several zipcode areas, in which the lowest family incomes were reported, had higher lead levels. More Latino children had higher lead levels than African American children. Latino children (i.e., 20.2%) who were 1-5 y of age had blood lead levels that were > or = 10 micrograms/dl. Young Latino children in this zone of Los Angeles may be at increased risk for lead exposure.

Adolescent↗
PubMedDate not supplied

Maternal blood lead level during pregnancy in South Central Los Angeles.

Twenty-five years of public health efforts produced a striking reduction in lead exposure; the blood lead average in the United States has decreased to less than 20% of levels measured in the 1970s. However, poor minority groups that live in large urban centers are still at high risk for elevated lead levels. In this study, our data showed that pregnant immigrants (n = 1,428) who live in South Central Los Angeles--one of the most economically depressed regions of California--have significantly higher (p < .0001) blood lead levels (geometric mean = 2.3 microg/dl [0.11 micromol/l]) than 504 pregnant nonimmigrants (geometric mean = 1.9 microg/dl [0.09 micromol/l]). The most important factors associated with lower blood lead levels in both groups were younger age; more-recent date of blood sampling (i.e., decreasing secular trend); and blood sampling in mid-autumn, instead of mid-spring (i.e., seasonal trend). Blood lead levels of immigrants were strongly dependent on time elapsed since immigration to the United States; each natural log increase in years of residence was associated with an approximately 19% decrease in blood lead levels. Although blood lead means for both groups were almost the same as the estimated national average, 25 of the 30 cases of elevated blood lead (i.e., > or = 10 microg/dl [0.48 micromol/l) occurred in the immigrant group. The odds ratio (95% confidence intervals within parentheses) for having elevated blood lead levels (a) was 9.3 (1.9, 45.8) if the immigrant engaged in pica; (b) was 3.8 (1.4, 10.5) if the immigrant had low dietary calcium intake during pregnancy; and (c) was .65 (.43, .98) for every natural log unit increase of years of residence in the United States. The control of pica and dietary calcium intake may offer a means of reducing lead exposure in immigrants.

Adolescent↗
PubMedDate not supplied

Blood lead level and blood pressure during pregnancy in South Central Los Angeles.

In many studies in which the relationship between blood pressure and blood lead level has been examined, investigators have found significant--but small--associations. There was only one previous report of a significant association of blood lead with blood pressure in pregnant women. We measured blood lead level and sitting blood pressure of 1,627 women in their third trimester of pregnancy. We eliminated subjects with known causes of hypertension. Most women (98.4%) were normotensive. We controlled for body mass index, age, and stress--among other factors--and constructed multiple-regression models of lead association with diastolic and systolic blood pressures. Immigrants (73% of total) had significantly higher blood lead levels and different blood pressures than nonimmigrants, suggesting that analysis be stratified by "immigrant, nonimmigrant" status. Positive relationships between blood lead level and blood pressure were found only for immigrants (p < or = .001). From the 5th to 95th blood-lead percentiles (0.9-6.2 microg/dl) in immigrants, systolic blood pressure increased 2.8 mm Hg, and diastolic blood pressure increased 2.4 mm Hg. Higher prior lead exposure of immigrants (97.7% from Latin countries) than nonimmigrants might explain the differential effect of these low levels of blood lead on blood pressure in nonimmigrants. Perhaps some immigrants are at higher risk than nonimmigrants for lead-associated elevated blood pressure during pregnancy, despite blood lead levels within the currently considered acceptable range.

Adult↗
PubMedDate not supplied

Medical accelerator safety considerations: report of AAPM Radiation Therapy Committee Task Group No. 35.

Ensuring safe operation for a medical accelerator is a difficult task. Users must assume more responsibility in using contemporary equipment. Additionally, users must work closely with manufacturers in promoting the safe and effective use of such complex equipment. Complex treatment techniques and treatment modality changeover procedures merit detailed, unambiguous written procedural instruction at the control console. A thorough "hands on" training period after receiving instructions, and before assuming treatment responsibilities, is essential for all technologists. Unambiguous written instructions must also be provided to guide technologists in safe response when equipment malfunctions or exhibits unexpected behavior or after any component has been changed or readjusted. Technologists should be given a written list of the appropriate individuals to consult when unexpected machine behavior occurs. They should be assisted in identifying aberrant behavior of equipment. Many centers already provide this instruction, but others may not. Practiced response and discussion with technologists should be a part of an ongoing quality assurance program. An important aspect of a safety program is the need for continuous vigilance. Table III gives a summary of a comprehensive safety program for medical accelerators. Table IV gives a list of summary recommendations as an example of how one might mitigate the consequences of an equipment failure and improve procedures and operator response in the context of the environment described. Most of these recommendations can be implemented almost immediately at any individual treatment center.

Biophysical Phenomena↗
PubMedDate not supplied

Isolated hypogonadotropic hypogonadism in a man with a history of head trauma during childhood.

OBJECTIVE: To report a case of isolated hypogonadotropic hypogonadism as a delayed consequence of major head injury. METHODS: We present the relevant history, findings on physical examination, and results of laboratory evaluation, and supportive data from appropriate reports in the literature are reviewed. RESULTS: A 37-year-old man with progressive loss of libido, impotence, and gradual loss of facial and axillary hair had sustained severe trauma to the head (sufficient to cause blindness in one eye) in a fall from a tree at 7 years of age. Physical examination and laboratory investigations substantiated the presence of isolated hypogonadotropic hypogonadism. Other causes of hypogonadotropic hypogonadism, including Kallmann's syndrome, were excluded. CONCLUSION: Severe head injury should be considered in the differential diagnosis of isolated hypogonadotropic hypogonadism. Long-term follow-up and endocrine assessment may be important in patients who have sustained severe head injury.

Journal Article↗
PubMedDate not supplied

Contamination of the surgeon's bare and gloved fingertips in cardiac operations.

The surgeon's bare fingertips and the external surface of gloved fingertips were examined for contamination by bacteria during the course of 27 cardiac surgical operations. Following the surgical scrub, positive colony counts were obtained in 20 (74%) of bare fingertip impressions (median colony count 4 [inter-quartile range, IQR, 0-9)], while at the conclusion of surgery positive counts were obtained in 15 (55.6%) fingertip impressions (median count 1 [IQR 0-6]; range 0-247; paired Wilcoxon test p = NS). Furthermore, positive colony counts at the start of the operation were obtained in none of the gloved fingertip impressions and at conclusion of surgery in 17 (62.9%) of the gloved fingertip impressions (median count 2 [IQR 0-6] p = 0.0002). There was no significant relationship between the total colony count on gloved fingertip impressions and the length of surgery (Pearson's r = 0.17, p = NS). Contrary to expectations there was no significant increase in the colony count on the bare fingertips at the conclusion of surgery. Although there was an increase in the bacterial count on the surgeon's gloved fingertips, this increase did not correlate with the length of surgery.

Cardiac Surgical Procedures↗
PubMedDate not supplied

Sprinting on a running track: a rare cause of a Lisfranc dislocation.

We present a case report of a young man who sustained a serious foot injury while sprinting in a straight line. We discuss the management of these injuries and emphasise the importance of a high index of suspicion amongst orthopaedic, casualty and radiology trainees.

Adolescent↗
PubMedDate not supplied

[Electron microscopic study of the DNA products of reverse transcription].

DNA-products synthesized on pre-mRNA's from rat liver and rabbit erythroidal bone marrow cells, on rabbit globin mRNA and the RNA-templates themselves have been examined by electron microscopy. In spreading conditions providing extension of molecules the sizes of DNA-products corresponded to sizes of RNA templates. Globin mRNA, pre-mRNA as well as cDNA synthesized on these templates in the presence of actinomycine D were seen as single-stranded molecules by electron microscopy. The preparations of cDNA synthesized in the absence of actinomycine D on the pre-mRNA template were represented by double-stranded molecules along side with sigle-sranded. Up to 10% of double-stranded DNA-product appeared to be branched; all branches of such molecules had the thickness and rigidity of double-stranded structures. The possible ways of formation of branched structures are discussed.

Chemical Phenomena↗