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Biomedical subjects

S Patel

Publications and source records attributed to S Patel.

857 records · Page 48Linked to original sources
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Corneal sensitivity and some properties of the tear film after laser in situ keratomileusis.

PURPOSE: To investigate central corneal sensitivity, lipid layer structure of the precorneal tear film, and tear volume after laser in situ keratomileusis (LASIK). METHODS: Central corneal sensitivity was measured using the Non-Contact Corneal Aesthesiometer. The aesthesiometer was mounted on a slit lamp and an airpulse of controlled pressure was directed onto the cornea. When central corneal sensitivity was reduced, a higher air pulse pressure was required to stimulate the cornea. The final central corneal sensitivity threshold measured was recorded in millibars. Tear lipid layer structure was assessed by optical interferometry and classified according to appearance using the Keeler Tearscope. Tear volume was measured using the phenol red cotton thread test. Subjects were recruited from a group of patients after LASIK who had experienced no complications (n=22). The average postoperative time was 14 weeks and measurements were taken on one eye. In bilateral cases, measurements were recorded from the right eye only. Average attempted correction was -6.30 D (range, -2 to -11 D). Age-matched controls were later recruited for central corneal sensitivity threshold (n=24). A second group of age-matched controls were recruited for tear volume and lipid layer structure (n=24). RESULTS: The median (range) was 1.1 mbars (0.2 to 4.3 mbars) after LASIK and 0.58 mbars (0.20 to 1.3 mbars) in the controls; the difference was statistically significant (P = .043). The lipid layer of the tear film tended to be thinner in eyes after LASIK compared with controls (P = .032). The mean (+/- SD) tear volume was 16.9 +/- 8.3 mm after LASIK and 19.8 +/- 7.1 mm in controls. This difference was not statistically significant (P = .492). CONCLUSION: At 14 weeks postoperatively, central corneal sensitivity was below normal levels and the tear lipid layer was thinner. The poorer quality lipid layer may predispose to symptoms of dry eye after LASIK.

Adolescent↗
PubMedDate not supplied

Antibodies to spermatozoa. VII humoral and cellular aspects of sperm inmunity and infertility.

The occurrence of sperm antibody in serum and cervical mucus of women from intertile couples in the serum of their male partners, as well as cellular immunity to sperm, has been studied by agglutination and immobilization techniques. For a total of about 260 couples, the tests on serum showed that 18% of the women and 8% of the men were positive by the Kibrick technique and that 15% of the women and 4% of the men were positive by the F-D technique. The women who were positive in their cervical mucus were 8% of the group by the K-agg (Kibrick agglutination) technique, 2% by the MIS-agg. (Microscale agglutination) technique, and 40% by the MIS-imm. (Microscale immobilization) tecnique. In considering all three techniques. 42% of a group of 132 women were positive. Cellular immunity to sperm, by the Migration Inhibition method, was positive in 18% and zero per cent of infertile and fertile women, respectively.

Antibody Formation↗
PubMedDate not supplied

High volume sutureless intraocular lens surgery in a rural eye camp in india.

BACKGROUND AND OBJECTIVE: To describe the use of small incision sutureless cataract surgery (SISCS) that permits high-volume, high-quality, and low-cost surgery. PATIENTS AND METHODS: We compared the speed, safety, and visual results of 1190 surgical techniques performed in a public eye camp in India. Intraocular lenses were received by 97% of patients (1154). Surgical techniques used were SISCS, phacoemulsification, and standard extracapsular cataract extraction (ECCE) technique. RESULTS: Postoperatively, 60.0% attained uncorrected vision of 6/24 or better. There was little difference in visual results or complication rates among the three techniques. The most striking finding is the speed of SISCS, which enables experienced surgeons to perform the technique in 3.8 to 4.2 minutes. CONCLUSION: We believe this surgical technique is of major importance especially in developing nations facing enormous surgical volumes and limited resources.

Humans↗
PubMedDate not supplied

When to remove an epidural catheter in a parturient with disseminated intravascular coagulation.

BACKGROUND AND OBJECTIVES: Pain from labor and delivery is often attenuated with epidural anesthesia. A complication of indwelling epidural catheters is intraspinal hematoma. The development of a bleeding diathesis can worsen complications markedly. CONCLUSIONS: Frequent assessment of neurologic status is important until the underlying cause of the coagulopathy can be treated and the bleeding resolves. If there is no indication of intraspinal bleeding, we recommend removing the catheter because of potential catheter migration. If bleeding is occurring around the catheter insertion site and possibly in the epidural or subarachnoid space, the catheter may be left in place to tamponade the insertion site. In cases of intraspinal hematoma, which can cause neurologic deficits, immediate decompression surgery is needed.

Acute Disease↗
PubMedDate not supplied

Determination of ochratoxin A in green coffee by immunoaffinity column cleanup and liquid chomatography: collaborative study.

A collaborative study was conducted to evaluate a method using immunoaffinity column cleanup with liquid chromatography (LC) for the determination of ochratoxin A (OTA) in green coffee at levels that could be included in possible future regulations of the European Union. The test portion was extracted with methanol-3% aqueous sodium hydrogen carbonate solution (50 + 50, v/v). The extract was filtered, and the filtrate was diluted with phosphate-buffered saline and applied to an immunoaffinity column containing antibodies specific for OTA. After washing, the toxin was eluted from the column with methanol and quantified by LC with fluorescence detection. Pairs of 4 homogeneous noncontaminated and naturally contaminated materials (mean levels of < 0.12, 2.44, 5.15, and 13.46 ng/g) and blank samples (< 0.12 ng/g) for spiking were sent to 20 participant laboratories from 8 countries. The materials were analyzed according to the method description and all difficulties encountered in the analysis were reported. Statistical analysis was carried out according to the Harmonized Protocol of the International Union of Pure and Applied Chemistry. The relative standard deviation for repeatability (RSDr) ranged from 7.42 to 20.94%, and the relative standard deviation for reproducibility (RSDR) ranged from 16.34 to 29.17%. The method showed acceptable within-laboratory and between-laboratories precision for green coffee materials, as evidenced by HorRat values of < or = 0.85, at the studied range, for spiked and naturally contaminated materials. The mean recovery was 92.8% for green coffee material spiked with OTA at a level of 4.82 ng/g.

Buffers↗
PubMedDate not supplied

Fine needle aspiration cytology of the adrenal gland.

The cytologic appearance of fine needle aspiration (FNA) specimens emanating from both symptomatic and incidental masses of the adrenal glands in 22 patients who attended a large cancer institution from 1976 to 1981 is described. Eligibility for the study required thorough clinical and radiologic follow-up for at least two years following the initial cytologic diagnosis. Histologic and ultrastructural correlations were performed when possible. Nine patients were found to have benign lesions, including five adrenal cysts, two adenomas, one nodular hyperplasia and one adrenal myelolipoma. Thirteen patients had malignant lesions, of which six were primary adrenal tumors, either neuroblastoma (two) or adrenocortical carcinoma (four). The overall sensitivity of FNA in detecting the presence of malignancy was 85%, while the number of patients correctly classified for all adrenal masses was 90%. The test was 100% specific for malignant lesions. It is concluded that FNA of adrenal masses is a safe and simple procedure with a high degree of accuracy. Its use appears to be especially justified in those patients with primary neoplasms of nonadrenal sites, in whom silent adrenal lesions are detected during radiologic surveys for metastatic disease. Fifteen of the patients fell into this category, yet over half (53%) of them were shown to have benign adrenal lesions, treatable with a conservative approach.

Adrenal Gland Diseases↗
PubMedDate not supplied

Model for predicting the optical performance of the eye in refractive surgery.

BACKGROUND: Predicting the outcome of refractive surgical procedures is one of the chief goals of the refractive surgeon. Besides perfecting the change required to nullify a refractive error, the optical quality of the postsurgical eye should be maximized. METHODS: A model eye useful for predicting the likely effects on the optical performance of the eye as a result of refractive surgical intervention is presented. The model features aspheric ocular interfaces, a gradient refractive index within the lens, and a uni-index cornea. The dimensions of the model parameters are taken from the literature. Baker's method of ray tracing through aspheric surfaces is used to predict the lateral spherical aberration of the eye for specific pupil sizes. The results for various operational conditions such as number of lens layers and corneal shape were calculated. RESULTS: The model predicts that optimal optical imagery is produced when the corneal profile is represented by a flattening ellipse (shape factor = .65 to .85). Ideally, in refractive surgery involving the cornea, the postoperative corneal contour should conform to this flattening ellipse.

Cornea↗
PubMedDate not supplied

Shape and radius of posterior corneal surface.

BACKGROUND: The posterior corneal surface is often ignored in predictive models concerned with refractive surgery. In previous studies, the radius of this surface has been measured in a variety of ways, primarily over a large chord diameter of the surface, with the common assumption that the surface is spherical. The asphericity of this surface has not been adequately addressed in the past. METHODS: An algorithm is derived for the calculation of posterior corneal surface apical radius and using characteristics of the anterior corneal surface and topographic corneal thickness variation. Anterior corneal asphericity was measured using a commercially available photoelectric keratoscope. Using a marked soft contact lens, a simple method of locating noncentral corneal sites is described as an aid to ultrasonic pachometry. RESULTS: In a group of 20 normal subjects ranging in age from 19 to 23 years, the average posterior corneal surface apical radius and asphericity (p) was 5.80 mm (SD = +/- 0.42) and 0.64 (SD = 0.37) for the vertical meridian, and 5.82 mm (SD = +/- 0.40) and 0.52 (SD = 0.30) for the horizontal meridian. Average central corneal thickness was 533 mu (SD = +/- 19). CONCLUSIONS: The average asphericity values are below 1, hence the posterior corneal surface is described as a flattening ellipse. The rate of flattening of this surface is greater than the rate of flattening along the averaged anterior corneal surface.

Adult↗
PubMedDate not supplied

PDPH in obstetric anesthesia: comparison of 24-gauge Sprotte and 25-gauge Quincke needles and effect of subarachnoid administration of fentanyl.

BACKGROUND AND OBJECTIVES: Postdural puncture headache (PDPH) is a frequent complication of spinal anesthesia. Some investigators have recommended the use of the Sprotte needle to reduce the incidence of this serious complication. This study prospectively compared the incidence of PDPH with two spinal needles of different size and design: the 24-gauge Sprotte (noncutting point) versus the 25-gauge Quincke (diamond, cutting point). The hypothesis that subarachnoid fentanyl will reduce the incidence of PDPH, as suggested in the literature, was also studied. METHODS: Only patients for emergency or elective cesarean delivery were studied. One hundred ninety four patients were randomly assigned to receive spinal anesthesia with one of the two needles (Sprotte, n = 96; Quincke, n = 98). Simultaneously, each patient was assigned to receive hyperbaric 0.75% bupivacaine local anesthetic or a combination of the same concentration of local anesthetic with 20 micrograms of fentanyl (Sprotte with fentanyl, n = 47; Sprotte without fentanyl, n = 49; Quincke with fentanyl, n = 49; Quincke without fentanyl, n = 49). All patients were evaluated during the first 4 postoperative days, and follow-up telephone interviews were conducted 3 weeks after discharge. RESULTS: Four patients (4.2%) in the Sprotte group and seven (7.1%) in the Quincke group developed PDPH. Three out of four patients with headache in the Sprotte and four out of seven in the Quincke group received fentanyl as an adjunct for spinal anesthesia. Two patients in the Sprotte group required an epidural blood patch as a therapy for PDPH. Two patients in the Quincke group had severe headache and required an epidural blood patch. CONCLUSIONS: In the current study, the use of the 24-gauge Sprotte spinal needle resulted in a low incidence of severe PDPH, but was not significantly different when compared with the use of a 25-gauge Quincke needle (oriented parallel to the longitudinal dural fibers). The addition of fentanyl to hyperbaric bupivacaine spinal anesthesia did not reduce the risk of PDPH.

Adult↗
PubMedDate not supplied

The effect of 5,6-dimethylxanthenone-4-acetic acid on tumour necrosis factor production by human immune cells.

5,6-dimethylxanthenone-4-acetic acid (5,6-MeXAA) is a potent anti-tumour agent which is undergoing early clinical evaluation. It was developed as an improved analogue of flavone acetic acid (FAA) which failed in clinical trial although it had impressive anti-tumour activity in mice. It has been postulated that one possible reason for the clinical failure of FAA was its inability to induce cytokines, especially tumour necrosis factor (TNF) in humans whereas this was seen as an important component of its mechanism of action in mice. Previous studies have demonstrated that 5,6-MeXAA induces mRNA for TNF in the human HL-60 cell line although the protein was not detected. This study has demonstrated mRNA for TNF alpha by RT-PCR in human and murine immune cells incubated with either 5,6-MeXAA, FAA or in culture medium alone. Using a bioassay technique 5,6-MeXAA and FAA were shown to induce TNF production in vitro by murine macrophages but TNF was not detected when human or murine peripheral blood mononuclear cells were stimulated with these agents. A small but significant production of TNF was seen in the HL-60 cell line after 5,6-MeXAA treatment suggesting 5,6-MeXAA can directly stimulate human cells to produce TNF albeit at low levels.

Animals↗