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Biomedical subjects

R Shapiro

Publications and source records attributed to R Shapiro.

535 records · Page 30Linked to original sources
PubMedDate not supplied

Determination of trace elements in foods by HCl-HNO3 leaching and flame atomic absorption spectroscopy.

Aluminum, iron, tin, zinc, calcium, magnesium, nickel, copper, chromium, cadmium, and potassium in foods can be extracted by HCl-HNO3 leaching and determined quantitatively using flame atomic absorption spectroscopy (AAS), with recoveries ranging from 90 to 110%. Thirty to 40 samples of almost any type of food sample can be analyzed routinely for 2 elements in 4-5 h. In contrast, one or 2 days are required when a wet-ash or dry-ash technique is used. Extraction consists of weighing 2-10 g samples into 125 mL Erlenmeyer flasks, adding 20 mL concentrated HCl-HNO3 (9 + 1), then heating in a 82- 93 degrees C water bath for 30 min. After cooling, samples are diluted to volume in 50 mL Nessler tubes and then filtered through No. 541 or 540 Whatman paper. The filtrate is analyzed directly by AAS.

Food Analysis↗
PubMedDate not supplied

Computed tomography of temporal bone pneumatization: 2. Petrosquamosal suture and septum.

The degree of visualization of the petrosquamosal (Körner's) septum on high-resolution axial computed tomography (CT) in 141 temporal bones (100 subjects) was analyzed. The superior and inferior parts of the septum were assessed separately and were seen in 75% and 41% of cases, respectively. There was no relation between the size of Körner's septum and pneumatization. The clinical relevance of this finding is discussed. The CT features of the ventral petrosquamosal suture also were investigated. The crista tegmentalis, a contribution of the petrosal tegmen to the mandibular fossa, was seen on CT as a polypoid excrescence projecting from the ventrolateral petrous pyramid. This knowledge is useful in the radiographic analysis of the course of longitudinal fractures of the petrous bone.

Cranial Sutures↗
PubMedDate not supplied

Pad-plate diffusion assay for virginiamycin in mash-type feeds.

An assay procedure has been developed for virginiamycin in mash-type feeds which includes removing fat interferences from the feeds by a rapid petroleum ether wash, a citric acid extraction, an acetone extraction, and the use of the pad-plate diffusion system. The procedure eliminates the need for compensatory curves prepared from feeds of the same or similar composition. Recoveries from 10 laboratory-prepared feeds containing 11.0 micrograms virginiamycin/g averaged 89.3% with a coefficient of variation (CV) of 5.76%. Recoveries from a laboratory-prepared feed containing 13.2 micrograms virginiamycin/g averaged 89.9% (CV 9.92%). The procedure is simple, reasonably accurate, and precise.

Animal Feed↗
PubMedDate not supplied

Maintaining confidentiality in a look-back investigation of patients treated by a HIV-infected dentist.

The spread of human immunodeficiency virus (HIV) from a Florida dentist with acquired immunodeficiency syndrome (AIDS) to several of his patients has generated considerable concern about the risk of HIV transmission during dental treatment. Accordingly, self-reporting of HIV infection and subsequent AIDS by a dentist at our medical center prompted notification and testing of patients at risk. Key features of the notification and testing process were (a) only patients who had undergone procedures deemed to pose appreciable risk of exposure to the dentist's blood were notified, (b) the identity of the dentist was shielded by not including in notification letters any identifying information other than the name of the medical center, and (c) patients' blood specimens were tested promptly for HIV antibodies and results were reported immediately to each patient to minimize the period of anxiety. HIV antibody testing was requested by 41 of the 88 patients to whom notification letters were sent, and all 41 were HIV negative after having undergone 395 procedures by the HIV-infected dentist. Review of the 88 patients' medical and dental records showed that at least 77 had received treatment by other health care providers at the medical center so that they would not be able to ascertain which provider had HIV infection. None of the patients who were notified by the medical center subsequently queried the dentist concerning possible HIV infection. Our experience demonstrates that look-back investigations can be conducted by institutions in a manner that substantially protects the identity of health care workers with HIV infection, minimizes the number of patients discomfitted, and avoids excessive utilization of personnel time. Even greater protection of the identity of health care workers with HIV infection presumably can be achieved when notification is undertaken by a public health agency.

Confidentiality↗
PubMedDate not supplied

Relaxation electromechanical delay of the quadriceps during selected movement velocities.

The purpose of this study was to quantify the time between the cessation of EMG activity and cessation of torque production, or relaxation electromechanical delay, (R-EMD) of the quadriceps at three angular movement velocities. A Biodex dynamometer passively moved the right knee of 25 males through a given range at three velocities (10, 60 and 120 degrees per second). Subjects were instructed to actively extend their knees to a visual target, then to immediately relax. Biodex torque and position data, as well as surface EMG from the right Vastus Medialis (VM), Rectus Femoris (RF) and Vastus Lateralis (VL) were sampled simultaneously. EMG cessation was determined when activity fell below a threshold based on the muscle's resting EMG. Torque cessation was determined when the slope of the relaxation curve decreased to 10% of the initial value. R-EMD time for each quadriceps head at each velocity was determined by calculating the difference between these two times. To examine reliability, subjects were retested four days later. Approximately two thirds of the subjects were unable to consistently perform the motor task of abrupt relaxation at some or all of the tested velocities. This variability was ascribed to motor control issues. Average R-EMD times for all subjects, muscle segments and velocities ranged from 249 +/- 68 ms to 276 +/- 51 ms during the first test session, and 239 +/- 46 ms to 300 +/- 59 ms during the second session. These data are important in identification of physiologically meaningful cessation of muscle contraction, and may be beneficial in research studies focusing on the areas of motor control and motor learning, computerized movement analysis, and prediction models for the determination of muscular force from the EMG signal.

Adult↗