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Biomedical subjects

D A Ellis

Publications and source records attributed to D A Ellis.

At least 19 recordsLinked to original sources
PubMed2001

Metal cation complexation and activation of reversed CPyI analogues of CC-1065 and duocarmycin SA: partitioning the effects of binding and catalysis.

The synthesis and examination of a novel class of reversed CPyI analogues of CC-1065 and the duocarmycins are described. Capable of a unique metal cation activation of DNA alkylation, these agents allowed the effects of the DNA binding domain (10(4)-fold increase in DNA alkylation rate and efficiency) to be partitioned into two components: that derived from enhanced DNA binding affinity and selectivity (10-80-fold) and that derived from a contribution to catalysis (250-5000-fold). In addition, the reversed enantiomeric selectivity of these sequence selective DNA alkylating agents provides further strong support for a previously disclosed model where it is the noncovalent binding selectivity of the compounds, and not the alkylation subunit or the source of catalysis, that controls the DNA alkylation selectivity.

Alkylating Agents↗
PubMed2001

Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment.

Following the introduction of hydrochlorofluorocarbon (HCFCs) and hydrofluorocarbon (HFCs) gases as replacements for the ozone-destroying chlorofluorocarbons (CFCs), it has been discovered that HCFCs/HFCs can degrade in the atmosphere to produce trifluoroacetic acid, a compound with no known loss mechanisms in the environment, and higher concentrations in natural waters have been shown to be mildly phytotoxic. Present environmental levels of trifluooracetic acid are not accounted by HCFC/HFC degradation alone. Here we report that thermolysis of fluorinated polymers, such as the commercial polymers Teflon and Kel-F, can also produce trifluoroacetate and the similar compound chlorodifluoroacetate. This can occur either directly, or indirectly via products that are known to degrade to these haloacetates in the atmosphere. The environmental significance of these findings is confirmed by modelling, which indicates that the thermolysis of fluoropolymers in industrial and consumer high-temperature applications (ovens, non-stick cooking utensils and combustion engines) is likely to be a significant source of trifluoroacetate in urban rain water ( approximately 25 ng l-1, as estimated for Toronto). Thermolysis also leads to longer chain polyfluoro- and/or polychlorofluoro- (C3-C14) carboxylic acids which may be equally persistent. Some of these products have recently been linked with possible adverse health and environmental impacts and are being phased out of the US market. Furthermore, we detected CFCs and fluorocarbons-groups that can destroy ozone and act as greenhouse gases, respectively-among the other thermal degradation products, suggesting that continued use of fluoropolymers may also exacerbate stratospheric ozone-depletion and global warming.

Acids↗
PubMed2001

The fate and persistence of trifluoroacetic and chloroacetic acids in pond waters.

The environmental fate of trichloro-, dichloro-, and monochloroacetic acids, and trifluoroacetic acid was investigated using field aquatic microcosms and laboratory sediment-water systems. Trifluoroacetic acid was extremely persistent and showed no degradation during a one-year field study, though it appeared to undergo transient partitioning within an unknown pond phase as the temperature of the surroundings was reduced. Of the three chloroacetic acids, trichloro had the longest residence time (induction and decay) (approximately 40 d), dichloro the shortest (approximately 4 d), and monochloro an intermediate residence time (approximately 14 d). Laboratory studies suggest that the biodegradation of trichloro-, dichloro-, and monochloroacetic acids leads primarily to the formation of chloride and oxalic, glyoxalic, and glycolic acids, respectively.

Acetates↗
PubMed2001

Survey of future injectables.

There has been an explosion in the technology of injectable filler materials for soft tissue augmentation of the face in the past decade. As a result, this is an exciting field and has provided surgeons who treat the aging face with newer, minimally invasive tools and techniques to augment the soft tissues of the face. In general, there are four classes of materials available for soft-tissue augmentation: synthetic, xenogeneic, homogeneic, and autogeneic. Moreover, within each class, these materials can be further divided, according to their longevity, into permanent materials, materials that last an undefined prolonged time, and temporary fillers. These products allow the surgeon and the patient to make choices that will give the best cosmetic results.

Collagen↗
PubMed2000

Development of an 19F NMR method for the analysis of fluorinated acids in environmental water samples.

This investigation was carried out to evaluate 19F NMR as an analytical tool for the measurement of trifluoroacetic acid (TFA) and other fluorinated acids in the aquatic environment. A method based upon strong anionic exchange (SAX) chromatography was also optimized for the concentration of the fluoro acids prior to NMR analysis. Extraction of the analyte from the SAX column was carried out directly in the NMR solvent in the presence of the strong organic base, DBU. The method allowed the analysis of the acid without any prior cleanup steps being involved. Optimal NMR sensitivity based upon T1 relaxation times was investigated for seven fluorinated compounds in four different NMR solvents. The use of the relaxation agent chromium acetylacetonate, Cr(acac)3, within these solvent systems was also evaluated. Results show that the optimal NMR solvent differs for each fluorinated analyte. Cr(acac)3 was shown to have pronounced effects on the limits of detection of the analyte. Generally, the optimal sensitivity condition appears to be methanol-d4/2M DBU in the presence of 4 mg/mL of Cr-(acac)3. The method was validated through spike and recovery for five fluoro acids from environmentally relevant waters. Results are presented for the analysis of TFA in Toronto rainwater, which ranged from < 16 to 850 ng/L. The NMR results were confirmed by GC-MS selected-ion monitoring of the fluoroanalide derivative.

Air Pollutants↗
PubMed2000

Laser facial skin resurfacing: discussion on erbium:YAG and CO2 lasers.

There are two lasers for resurfacing. The erbium:YAG laser and the CO2 laser both have different physical and physiologic differences when striking the skin. Therefore, each laser gives a different result. This article reviews the use of the Sharplan Silktouch CO2 laser for 4 years and the erbium:YAG laser for 1 year. In the last year, we have performed 40 laser procedures with the erbium:YAG laser. Discussion ensues regarding the differences and similarities of the two lasers as well as the difficulties and complications.

Carbon Dioxide↗
PubMed2000

Intellectual, cognitive, and academic performance among sons of alcoholics, during the early school years: differences related to subtypes of familial alcoholism.

BACKGROUND: Research on intellectual and cognitive functioning of children of alcoholics has been marked by inconsistency, with some studies unable to document deficits. This discrepancy may reflect the substantial heterogeneity found in the alcoholic population and among families of alcoholics. The current study sought to examine the effects of familial alcoholism subtypes on intellectual, cognitive, and academic performance in early school-aged sons of alcoholics. METHODS: Subjects for the present study were 198 elementary-age boys who were participants in the larger MSU-UM Longitudinal Study. Familial alcoholism subtypes were determined based on fathers' alcoholism and antisocial personality disorder diagnoses. Intellectual functioning was measured with the Wechsler Intelligence Scale for Children-Revised (WISC-R); academic achievement was measured with the Wide Range Achievement Test-Revised. In addition, Mazes and Freedom from Distractability factor scores of the WISC-R were used to assess abstract planning and attention abilities. RESULTS: Children of antisocial alcoholics (AALs) displayed the worst IQ and academic achievement compared with children of nonantisocial alcoholics (NAALs) and controls. In addition, children of AALs displayed relatively poorer abstract planning and attention abilities compared with children from control families. Regression analyses revealed that familial alcoholism subtype continued to account for variance in child intellectual ability even when other factors were excluded. CONCLUSIONS: Findings indicate that children from AAL families are most susceptible to relative intellectual, cognitive, and academic deficits. The study further supports the proposition that familial risk characteristics (i.e., paternal alcoholism and antisociality) may serve as effective indicators of family risk for poor intellectual outcome among offspring as early as the elementary school years.

Adult↗
PubMed1999

Augmentation of the nasal spine area with tissue bone matrix sponge.

OBJECTIVE: High-density tissue bone matrix (TBM) sponge is a homograft derived from human cadaver. It is reported to be osteoinductive. The objective of this paper is to measure the bone formation and cosmetic effect of TBM sponge implanted in the nasal spine area of patients undergoing rhinoplasty with retraction of this region and loss of nasal tip support. DESIGN: The study was designed as a prospective trial. SETTING: Patients were selected from private facial cosmetic practice and from public otolaryngology practice. PATIENTS: Six patients were selected who had retraction of the nasal spine area and loss of tip support. INTERVENTION: Patients had implantation of the TBM sponge in the nasal spine area either as a sole procedure or in conjunction with other rhinoplasty maneuvers. MAIN OUTCOME MEASURES: Palpation was used to assess position, size and consistency of the implant. Cosmetic effect was assessed by computer imaging, which was used to measure nasolabial angle and tip projection. Bone formation was assessed by computed tomography scanning. RESULTS: The implant could be palpated in all six patients at 1 month postoperatively, but at 3 months was either smaller or could not be felt. Nasolabial angle and tip projection were improved in all patients initially, but 3 months following surgery this cosmetic improvement was maintained in only two patients. At 3 months, CT scanning showed no evidence of bone formation. CONCLUSION: The TBM sponge was not found to be osteoinductive or permanent when implanted in the nasal spine area and therefore is not a good implant in that region.

Bone Matrix↗
PubMed1998

Chlamydia trachomatis infections in female military recruits.

BACKGROUND: Asymptomatic genital Chlamydia trachomatis infections in women can lead to pelvic inflammatory disease, infertility, and ectopic pregnancy. To design a chlamydia-control program, we conducted a large survey of women in the U.S. military. METHODS: From January 1996 through December 1997, urine samples from 13,204 new female U.S. Army recruits from 50 states were screened by ligase chain reaction for C. trachomatis infection. Information on potential risk factors was obtained by questionnaire. With multivariate analysis, we identified criteria for a screening program. RESULTS: The overall prevalence of chlamydial infection was 9.2 percent, with a peak of 12.2 percent among the 17-year-old recruits. The prevalence was 15 percent or more among the recruits from five southern states. The following risk factors were independently associated with chlamydial infection: having ever had vaginal sex (odds ratio for infection, 5.9), being 25 years of age or less (odds ratio, 3.0), being black (odds ratio, 3.4), having had more than one sex partner in the previous 90 days (odds ratio, 1.4), having had a new partner in the previous 90 days (odds ratio, 1.3), having had a partner in the previous 90 days who did not always use condoms (odds ratio, 1.4), and having ever had a sexually transmitted disease (odds ratio, 1.2). A screening program for subjects 25 years of age or less (87.9 percent of our sample) would have identified 95.3 percent of the infected women. CONCLUSIONS: Among female military recruits, the prevalence of chlamydial infection is high. A control program that screens female recruits who are 25 years old or younger with urine DNA-amplification assays has the potential to reduce infection, transmission, and the sequelae of chlamydial infection.

Adolescent↗
PubMed1998

Anatomy of the motor innervation of the corrugator supercilii muscle: clinical significance and development of a new surgical technique for frowning.

OBJECTIVE: This study was conducted to determine the motor innervation of the corrugator supercilii muscle and, based on this information, develop a new surgical technique to treat patients with hyperfunctional corrugator muscles with deep vertical glabellar creases. METHOD: Microdissection of five fresh-frozen cadaveric heads was performed. Following this, patients presenting with a complaint of vertical glabellar creases (frown lines) due to hyperfunctional corrugator supercilii muscles were offered a new surgical technique to divide the nerve lateral to its entry into the corrugator supercilii muscle. RESULTS: The motor innervation of the corrugator supercilii muscle is constant and predictable in its course. Patients treated with motor nerve neurotomy showed considerable weakening of the corrugator supercilii muscle function as determined by clinical testing; however, the nerve lysis did not affect the glabellar depressor muscles. CONCLUSIONS: The anatomy of the motor nerve supply to the corrugator supercilii muscle is described. Lysis of the nerve appears to be safe, reliable, and effective in weakening the strength of the corrugator supercilii muscles and improving the appearance of vertical glabellar creases.

Cadaver↗
PubMed1997

Cosmetic upper-facial rejuvenation with botulinum.

OBJECTIVE: This study was conducted to evaluate the cosmetic use of botulinum toxin type A (Botox), which blocks the release of acetylcholine at the presynaptic neuromuscular junction leading to an irreversible, but temporary chemical denervation muscular paralysis and weakness. This produces a significant cosmetic improvement of wrinkling in the upper face due to hyperfunctional animation. METHOD: A prospective clinical study representing our experience with this new technique is presented. Patient selection and evaluation, classification of animation lines, techniques, results and complications are discussed. In a 15-month period, 23 patients with seven anatomic sites were injected. Twenty-three patients had the lateral aspect and the inferior aspect of their squint lines injected, and 26 patients had their glabellar frownlines injected. RESULTS: Significant improvement occurred to the average depth and length of the glabellar frownlines. The subjective improvement by the patients was also significant. Regarding the crow's feet, the lateral canthal lines showed more improvement than the inferior lateral canthal lines because the latter has a greater component of zygomaticus major and minor muscle, which contributes to the inferior lateral squint line. CONCLUSION: Botox is a safe, easy-to-use, effective modality for the temporary elimination of hyperfunctioning upper-facial muscles.

Botulinum Toxins, Type A↗
PubMed1997

The carbon dioxide laser. An alternative for the treatment of actinically damaged skin.

BACKGROUND: The treatment of complex and diffuse actinic keratoses involving the face presents a problem in that they frequently recur despite traditional treatment modalities. The carbon dioxide (CO2) laser is an effective method for resurfacing actinically damaged facial skin. OBJECTIVE: The purpose of this study is to show the usefulness of the CO2 laser for the treatment of actinically damaged skin in patients with proven actinic keratoses and squamous cell carcinoma in situ of the face. METHODS: In an office surgery setting, the Sharplan 1030 or 40C CO2 laser with the SilkTouch flashscanner attachment was utilized to treat various regions of the face in 14 patients. RESULTS: All patients were satisfied with the aesthetic outcome of their laser procedures and no clinical evidence of residual or recurrent lesions have been noted. There were no long-term complications reported. CONCLUSIONS: Based on this preliminary report, the CO2 laser appears to be an excellent alternative for the surgical treatment of premalignant lesions of the face and can be used effectively without significant complications.

Adult↗
PubMed1997

Facial rejuvenation with botulinum.

Botulinum toxin type A (Botox) blocks the release of neurotransmitter acetylcholine at the presynaptic neuromuscular junction leading to an irreversible, but temporary muscular paralysis and weakness. This can produce a significant improvement of wrinkling in the upper face caused by the actions of the facial muscles. A prospective clinical study representing a 15-month experience with this new technique is presented. Patient selection and evaluation, classification of animation lines, techniques, results, and complications are discussed.

Botulinum Toxins, Type A↗
PubMed1995

Expanded pectoralis major myocutaneous flaps in head and neck surgery.

The use of tissue expanders in head and neck surgery has been popularized since the early 1980s. Tissue expanders are currently used in nasal reconstruction, alopecia, and other head and neck defects when there is inadequate tissue or when transposition of a local flap would create a significant donor-site deformity. Occasionally, situations in head and neck reconstruction arise where local, regional, or free flaps are not available or sufficient for head and neck reconstruction. In these situations, the use of controlled tissue expansion can be employed for enlarging myocutaneous flaps for head and neck reconstructive surgery. Two cases illustrated here present the principles and techniques of this means of reconstruction.

Aged↗