Biomedical subjects

M Motamedi

Publications and source records attributed to M Motamedi.

At least 19 recordsLinked to original sources

PubMed2006

Operative treatment of anterior heterotopic bone formation of the elbow in a patient with severe haemophilia A.

There is no statistical data on the incidence of heterotopic ossification among patients with haemophilia, and a few reports documenting this entity in haemophilia are available. Although post-traumatic heterotopic ossification about the elbow is a well-recognized complication, we are not aware of any previously reported case in haemophiliacs. An 8-year-old boy with severe haemophilia A presented with fixed elbow in 80 degrees of flexion. Radiographs disclosed a mature anterior heterotopic ossification in the form of complete ulnohumeral bony bridge. Surgical excision of the heterotopic bone was performed. A full elbow range of motion was obtained after long-term physiotherapy. We conclude that this surgery is safe and successful in haemophilic patients, if performed at the right time under optimal situation.

Child↗

PubMed2003

Non-invasive monitoring of commonly used intraocular drugs against endophthalmitis by Raman spectroscopy.

PURPOSE: To develop a non-contact and non-invasive method for quantification of the local concentration of certain antibiotic and antifungal drugs in the eye. STUDY DESIGN/MATERIALS AND METHODS: An integrated CCD-based Raman spectroscopic system designed specifically for ophthalmic applications was used to non-invasively detect the presence of ceftazidime and amphotericin B in ocular media. Specific Raman signatures of the above named drugs were determined for various concentrations that were injected through a needle in the aqueous humor of rabbit eyes in vivo. Raman spectra were subsequently acquired by focusing an argon laser beam within the anterior chamber of the eye. RESULTS: Compared to ocular tissue, unique spectral features of ceftazidime appeared near 1,028, 1,506, 1,586, and 1,641 cm(-1). Amphotericin B exhibited its characteristic peaks at 1,156.5 and 1,556 cm(-1). The amplitude of the spectral peak corresponding to these drugs (acquired by 1 second exposure time and 25 mW of laser power) were determined to be linearly dependent on their local concentration in the anterior chamber of the eye. CONCLUSIONS: Raman spectroscopy may offer an effective tool to non-invasively assess the local concentration of the delivered drugs within the ocular media. This technique potentially could be used to investigate the pharmacokinetics of intraocular drugs in vivo either from a releasing implant or a direct injection.

Amphotericin B↗

PubMed2002

Noninvasive detection of ganciclovir in ocular tissue by Raman spectroscopy: implication for monitoring of drug release.

UNLABELLED: Treatment of various pathological conditions in ophthalmology, such as cytomegalovirus (CMV) retinopathy and endophthalmitis, requires a local drug intervention rather than a systemic approach. Accurate knowledge of intraocular drug concentration can permit the ophthalmologist to maintain drug levels within the therapeutic levels necessary for an optimal prognosis, while preventing or minimizing toxicity associated with drug overdose. PURPOSE: To develop a noninvasive/noncontact method for quantification of the local concentration of ganciclovir in the ocular media. METHODS: An integrated CCD-based Raman spectroscopic system designed specifically for ophthalmic applications was used to noninvasively detect the presence of ganciclovir in the ocular media. Various known concentrations of ganciclovir were injected into the aqueous humor of rabbit eyes in a pilot study, in vivo. Raman spectra were then acquired by focusing an argon laser beam within the anterior chamber of the eye. The specific Raman signature of ganciclovir was assessed at several concentrations. RESULTS: Spectral features unique to ganciclovir were identified and distinguished from those of ocular tissue. The amplitudes of the spectral peaks corresponding to ganciclovir exhibited a linear dependence on the local concentration of the drug in the anterior chamber of the eye. CONCLUSION: Raman spectroscopy may offer an effective tool for the noninvasive assessment of the local concentration of ganciclovir in the ocular media. This technique offers the potential to determine both the amount and the rate of the drug release from implants designed to deliver antiviral drugs locally within the eye. The availability of such data could enable the ophthalmologist to improve treatment efficacy by avoiding premature or late surgical replacement of the implants.

Animals↗

PubMed2001

Effects of 5-aminolaevulinic acid on human ovarian cancer cells and human vascular endothelial cells in vitro.

Results are reported on the cellular effects and the sensitivity of cultured tumor epithelial cells (TEC) derived from human ovarian cystadenocarcinoma and human umbilical vein-derived endothelial cells (HUVEC) to exogenous 5-aminolaevulinic acid (ALA) and ALA-induced photodynamic therapy (PDT). Cellular alterations and PDT efficiency were evaluated using colorimetric thiazolyl blue (MTT) assay, trypan blue exclusion assay, electron microscopy, and gel electrophoresis. ALA-induced protoporphyrin IX (PpIX) accumulation in TEC was associated with a concentration and time-dependent significant decrease in mitochondrial activity, increase in cell membrane permeability, and dark toxicity. Maximum PpIX loaded TEC demonstrated a high sensitivity to PDT. Neither cellular alterations nor PDT effects were observed in HUVEC under identical experimental conditions. These results indicate a potential clinical value for the use of ALA-mediated PDT to treat minimal residual disease in mucinous ovarian carcinoma. In addition, the ALA-induced PpIX cytotoxicity may be exported to a new chemotherapeutic regimen via a conventionally viewed photochemotherapeutic agent.

Aminolevulinic Acid↗

PubMed2001

Diode laser assisted transcervical tubal sterilization: an in vivo study in rabbits.

BACKGROUND AND OBJECTIVE: To investigate the sterilization effectiveness of endoluminal tubal photocoagulation on tubal lumen obliteration. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four female rabbits were subjected to laparotomy and hysterotomy. Endoluminal tubal photocoagulation was induced over a length of 3 cm in the proximal, extramural fallopian tube by using a cylindrical diffusing tip that emitted diode laser radiation at 805 and 980 nm wavelengths. Tubal patency was evaluated by observing patterns of injected methylene blue and/or breeding success rates. RESULTS: Postoperative recovery was uneventful in all animals. Evidence of occlusion of the tubal lumen included a negative methylene blue test in all 12 tubes treated (tubal occlusion rate 100%) and failure to conceive in 17 of 18 uteri (contraception rate 94.5%). Although identical power settings were used, distinctly lower tubal surface temperatures (about 10 degrees C) were obtained with the 805 nm diode laser as compared to the 980 nm diode laser. CONCLUSIONS: The described endoluminal tubal photocoagulation method using a diode laser emitting longer wavelengths (e.g., 980 nm) is suitable for safe and effective sterilization in rabbits and has potential as a new transcervical tubal sterilization method for humans.

Animals↗

PubMed2001

Raman spectroscopy in ophthalmology: from experimental tool to applications in vivo.

Raman spectroscopy is a qualitative and quantitative optical technique for determining the molecular composition of matter. Improvements in spectroscopic instruments, especially the modality to detect low light level signals extended the Raman technique to biomedical applications, even in delicate structures like the eye. The purpose of this paper was to make an inventory of performed applications of Raman spectroscopy in biomedical science and especially in ophthalmology. A literature search was done using Medline, Current Contents, a patent server on the Internet, and references found in articles and patents. This search revealed a variety of Raman techniques and applications in biomedical research, and an increasing flow of articles starting in the late 1970s on Raman spectroscopy in ophthalmology. This increase in literature about Raman spectroscopy in ophthalmology feeds the expectation that this valuable technique will be introduced in the future into clinical practice.

Animals↗

PubMed2001

Noninvasive Raman spectroscopic identification of intraocular lens material in the living human eye.

PURPOSE: To develop a safe noninvasive technique for identifying the material of intraocular lenses (IOLs) implanted in patients. SETTING: Center for Biomedical Engineering and the Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, USA. METHODS: Raman spectroscopy was used to noninvasively identify the type of IOL implanted after previous cataract surgery in 9 eyes of 6 patients who were legally blind as a result of eye disease. Three IOLs were characterized: poly(methyl methacrylate) (PMMA) (n = 5), acrylic (n = 3), and silicone (n = 1). Confocal Raman spectroscopy was used with a laser power of 95 microW and exposure time of 1 second. RESULTS: Distinct spectral peaks associated with each type of IOL were obtained. These included spectra peaks at 2840 cm(-1), 2946 cm(-1), and 3000 cm(-1) for PMMA; 2917 cm(-1), 2939 cm(-1), and 3055 cm(-1) for acrylic; and 2900 cm(-1), 2961 cm(-1), and 3048 cm(-1) for silicone. The procedure was well accepted by patients, and there were no complications. CONCLUSIONS: The specific Raman spectra of the IOLs allowed for noninvasive determination of IOL material with the use of a safe light dose and an exposure time of 1 second.

Acrylic Resins↗

PubMed2000

Release of synaptic zinc is substantially depressed by conventional brain slice preparations.

Research on synaptically-released zinc is frequently done in vitro with acute brain slice preparations. We show here the in vitro hippocampal slice preparation has two major pitfalls for zinc research. First, up to 50% of the synaptic zinc is lost during slice cutting and/or the first 10 min of slice incubation, with the losses being most pronounced on the edges of the slice. Second, the release of the remaining zinc from a slice is substantially depressed (up to 50%) at the low temperatures (32 degrees C) typically used for brain slice studies. In concert, these effects reduce zinc release about 75% in vitro, compared to in vivo. Implications for research on synaptically-released zinc are discussed.

Animals↗

PubMed2000

Evidence that synaptically-released zinc contributes to neuronal injury after traumatic brain injury.

Prior evidence indicates that synaptically-released zinc enters postsynaptic neurons in toxic excess during ischemia and seizures. In addition, prevention of this zinc translocation has been shown to be neuroprotective in both ischemia and seizures. Here we show evidence that the same translocation of zinc from presynaptic boutons into postsynaptic neurons occurs after mechanical injury to the brain. Specifically, using a rat model of traumatic brain injury, we show that trauma is associated with (i) loss of zinc from presynaptic boutons (ii) appearance of zinc in injured neurons, and (iii) neuroprotection by intraventricular administration of a zinc chelator just prior to brain impact. The possible use of zinc chelators for neuroprotection after head trauma is considered.

Aminoquinolines↗

PubMed2000

A study of aminolevulinic acid-induced protoporphyrin IX fluorescence kinetics in the canine oral cavity.

BACKGROUND AND OBJECTIVE: 5-Aminolevulinic acid-induced protoporphyrin IX is a promising photosensitizer that could enhance the spectroscopic contrast between normal and diseased oral tissues. Knowledge of the pharmacokinetics and effects on tissue type are important for diagnostic and therapeutic procedures. STUDY DESIGN/MATERIALS AND METHODS: Dogs randomly were administered five doses of 5-aminolevulinic acid: 5, 25, 50, 75, and 100 mg/kg. The fluorescence was recorded from buccal mucosa, gums, tongue, and facial skin using a fiberoptic probe connected to an optical multichannel analyzer. Blood samples were collected for hematologic and serum biochemical analysis. Pharmacokinetic parameters of interest were estimated using a compartmental model. RESULTS: Protoporphyrin fluorescence at all sites reached a peak in 2-6 hours, and returned to baseline in 24-31 hours, depending on the dose. Plasma protoporphyrin peaked earlier than oral tissues. CONCLUSION: The rate of synthesis of protoporphyrin, and its conversion to heme products are dose dependent. Different tissues have different pharmacokinetic response.

Aminolevulinic Acid↗

PubMed2000

Tubal sterilization by means of endoluminal coagulation: an in vivo study in rabbits.

This study was conducted to investigate the effectiveness and safety of endoluminal tubal coagulation in obliterating the tubal lumen in rabbits. Forty female rabbits were subjected to laparotomy and hysterotomy. Endoluminal tubal coagulation was induced over a length of 3 cm in the proximal, extramural fallopian tube by using a heated stainless steel cannula or a cylindrical diffusing tip emitting argon laser radiation for one to 5 minutes. Tubal patency was evaluated by observing patterns of injected methylene blue and/or breeding success rates. Postoperative recovery was uneventful in all animals. A negative methylene blue test indicated occlusion in 51 of 52 tubes (tubal occlusion rate 98.1%), and a contraception rate of 100% in all 17 uteri in which the tube had been treated. The described endoluminal tubal coagulation method proved suitable for safe and effective sterilization in rabbits and has potential as a new transcervical tubal sterilization method for humans.

Animals↗

PubMed2000

Mixing and sulphate-reducing activity of bacteria in swelling, compacted bentonite clay under high-level radioactive waste repository conditions.

AIM: The fate of micro-organisms in the bentonite clay surrounding high-level radioactive waste (HLW)-containing copper canisters in a future Swedish underground (500 m) repository were investigated. METHODS AND RESULTS: Laboratory experiments were designed in which the mixing of various bacterial species with swelling bentonite was studied. A clear trend of fewer cultivable bacteria at depth was seen in the clay. This trend was consistent as the incubation time was increased from 8 h to 28 weeks. Sulphate-reducing bacteria were found to be active, reducing sulphate at the lowest density studied, 1.5 g cm-3, but sulphate reduction activity ceased at higher densities. CONCLUSIONS: The number of viable micro-organisms in an HLW repository bentonite clay buffer will decrease rapidly during swelling and very few viable cells will be present at full compaction. SIGNIFICANCE AND IMPACT OF THE STUDY: Sulphate-reducing bacteria will most probably not be able to induce corrosion of HLW-containing copper canisters.

Bacteria↗

PubMed2000

Ventricular arrhythmias following thermal damage of epicardial tissue: possible causes and clinical implications.

Epicardial heating may be used for ventricular tachycardia (VT) ablation and transmyocardial revascularization. However, the potential risks of thermal epicardial injury, including arrhythmia, have not been fully explored. This study relates the pathologic and arrhythmic sequellae of epicardial heating when applied with a diode laser at varying doses. Acute pathology and dosimetry were determined in a group of normal dogs using 2-3 W over 30-90 seconds. Another group received a similar dose range before undergoing 24-hour monitoring, and electrophysiological testing was done at 4 weeks. In this group, four dogs each received 12 lesions (90-180 J) according to a randomized block design. Another dog received nine lower dose lesions (30-120 J). Acute lesions measured 2.5-8.0-mm wide by 4-8.5-mm deep. Charring and vaporization were common when 3 W were applied over 45 seconds. Within 24 hours, VT with features of abnormal automaticity occurred in all dogs receiving this dose. The dog in whom lower doses induced coagulation only had no VT. Four weeks later, electrophysiological study induced no VT. At this time fibrosis and granulation tissue were organizing the contraction band necrosis seen acutely, and some lesion borders were becoming calcified. No major vessels had been damaged. Abnormal automaticity and VT may occur if thermal damage of the epicardium exceeds coagulation. This could be related to tissue injury caused by sudden water vaporization, and may have clinical relevance given the growing indications for myocardial heating.

Acute Disease↗

PubMed2000

Brain tumor demarcation using optical spectroscopy; an in vitro study.

Optical spectroscopy for brain tumor demarcation was investigated in this study. Fluorescence and diffuse reflectance spectra were measured from normal and tumorous human brain tissues in vitro. A fluorescence peak was consistently observed around 460 nm (+/- 10 nm) emission from both normal and tumorous brain tissues using 337 nm excitation. Intensity of this fluorescence peak (F460) from normal brain tissues was greater than that from primary brain tumorous tissues. In addition, diffuse reflectance (Rd) between 650 and 800 nm from white matter was significantly stronger than that from primary and secondary brain tumors. A good separation between gray matter and brain tumors was found using the ratio of F460 and Rd at 460 nm (Rd460). Two empirical discrimination algorithms based on F460, Rd625, and F460/Rd460 were developed. These algorithms yielded an average sensitivity and specificity of 96% and 93%, respectively.

Algorithms↗

PubMed1999

Slow intramural heating with diffused laser light: A unique method for deep myocardial coagulation.

BACKGROUND: Catheter ablation of postinfarction ventricular tachycardia (VT) may be limited by insufficient myocardial coagulation or excessive endocardial or epicardial damage. We propose that volumetric heating restricted to intramural sites may improve the outcome and safety of this procedure, especially if delivered at rates that enhance heat conduction and forestall adverse tissue changes. METHODS AND RESULTS: A novel optical fiber with a diffusing tip for direct intramural, volumetric laser heating was tested via thoracotomy and percutaneously in normal dogs. Low-power (2.0- to 4.5-W) diode laser light (805 nm) diffused within tissue induced large lesions but no visible surface damage, mural thrombi, or transmural perforation. Mean lesion depth approximated tip length (10 mm). Mean lesion widths in the thoracotomy and percutaneous groups were 5.8+/-0.5 to 9.1+/-0.84 mm and 5.2+/-0.85 to 7.9+/-1.1 mm, respectively, depending on the light dose. Mean volumes in the percutaneous group were 1006+/-245 to 2471+/-934 mm. ST-segment depression, appearing in unfiltered bipolar electrograms recorded from the guiding catheter, was specific for lesion induction. All dogs survived the protocol, which included a 1-hour observation period. In cross section, lesions were elliptical to spherical and characterized by extensive contraction-band necrosis abruptly bordering viable tissue. No platelets or fibrin adhered to the endocardium. CONCLUSIONS: Slow, volumetric, and direct intramyocardial heating induces large, deep lesions without hazardous tissue damage. Such heating might cure postinfarction VT more successfully and safely than present techniques. Further testing and development of this method seem warranted.

Animals↗

PubMed1999

Laser ablation of urethral hair.

BACKGROUND AND OBJECTIVE: Two separate cases involving laser ablation of hair follicles in the neourethra are described. STUDY DESIGN/MATERIALS AND METHODS: Urethral hair developed secondarily to free-flap urethroplasty for congenital urethral defects. In both cases, cystoscopic depilation with electrocautery fulguration was attempted on multiple occasions. RESULTS: No improvement was seen; therefore, laser ablation was employed. Both patients remain free of regrowth at greater than one year of follow-up.

Adult↗

PubMed1999

Identification of intraocular lens materials using confocal Raman spectroscopy.

PURPOSE: To develop and test a noninvasive method to identify intraocular lens (IOL) materials in vitro. SETTING: Center for Biomedical Engineering and the Department of Ophthalmology, University of Texas Medical Branch, Galveston, Texas, USA. METHODS: A laser confocal Raman spectroscopy system (Conforam) was used for the noninvasive assessment of Raman spectra in the lower and the higher spectral regions (299.1 to 1833.7 cm-1 and 2633.8 to 3819.6 cm-1, respectively) of 4 IOL materials: silicone, poly(methyl methacrylate) (PMMA), acrylic, and hydrogel. RESULTS: Each lens material showed a distinctive spectrum in both the higher and the lower spectral regions. Most materials had unique peaks and a distinct profile using 1 mW of laser power and a 1 second exposure time. All materials still had a unique spectrum in both the higher and the lower region that allowed 1 material to be distinguished from the others. CONCLUSIONS: A Conforam differentiated silicone, PMMA, acrylic, and hydrogel lenses in vitro. Raman spectroscopy using the Conforam may provide a fast, safe, and reliable noninvasive method to gain information about the material of an implanted IOL and the stability of lens materials and their coatings.

Acrylates↗

PubMed1999

Non-invasive assessment of ocular pharmacokinetics using Confocal Raman Spectroscopy.

A Laser Scanning Confocal Raman Spectroscopy (LSCRS) system was applied for the non-invasive quantification of the transport of a drug through the rabbit cornea in vivo. Employing LSCRS, the changes in the amplitude of a drug-specific Raman signal were assessed over time in the tearfilm and corneal epithelium of the living rabbit eye (n = 6), after topical application of 25 microL Trusopt 2%. This allowed for quantification of pharmacokinetic variables. The effect of the drug on corneal hydration was also monitored. LSCRS demonstrated adequate sensitivity and reproducibility, for continuous real-time monitoring of the Trusopt concentration. Each concentration-time curve had a bi-phasic trend; the rapid initial phase (t<8 min.) corresponds to the nonproductive losses of Trusopt from the tears (k10 = 0.24+/-0.04 min(-1), and the slower later phase (t>20 min.) is the result of transfer of the drug from the corneal epithelium to the stroma (k23 = 0.0047+/-0.0004 min(-1). Drug absorption into the corneal epithelium occurred at a rate of k12 = 0.034+/-0.006 min(-1). Trusopt caused an acute dehydrating effect, with a maximum decrease in corneal hydration of approximately 15% at approximately 60 min. following application of the drug. LSCRS has the specificity, sensitivity, reproducibility and spatial resolution for employment as a potentially valuable tool for the study of ocular pharmacokinetics.

Animals↗