Biomedical subjects

S P Sarma

Publications and source records attributed to S P Sarma.

8 recordsLinked to original sources

PubMed2003

Functional characterization of the pentapeptide QYNAD on rNav1.2 channels and its NMR structure.

The endogenous pentapeptide QYNAD (Gln-Tyr-Asn-Ala-Asp) is present in human cerebrospinal fluid (CSF), and its concentration is increased in demyelinating diseases. QYNAD was synthesized and its action on the rNav1.2 voltage-gated sodium channel alpha-subunit was studied using whole-cell recordings in a heterologous expression system. The effects were seen only upon equilibration of the peptide in the external bath solution for at least 10 min before the commencement of whole-cell experiments. The steady-state activation curve showed a rightward shift of 10 mV, while the steady-state inactivation curve showed a leftward shift of 5 mV. Frequency-dependent inhibition of the sodium current amplitude was observed at 2-10 Hz, in the presence of external QYNAD, but was not seen when applied internally. Fits of the whole-cell sodium current traces by Hodgkin-Huxley equations revealed subtle changes in the voltage-dependent rate constants governing the transition of the activation and the inactivation gates. Two dimensional NMR spectroscopy revealed the absence of medium and long-range Nuclear Overhauser effects (NOEs), which indicates that the peptide does not adopt any canonical secondary structure in solution. In summary, our studies show that although the pentapeptide QYNAD does not have a defined structure in solution, it has defined actions on the rNav1.2 voltage-gated sodium channel isoform.

Animals↗

PubMed2001

Fluoroscopically guided Norplant removal.

The Norplant contraceptive implant system is a commonly used method of contraception worldwide. Implant placement and removal are usually simple office-based outpatient procedures. Norplant removal can occasionally become difficult, usually secondary to improper insertion. In these instances, we describe a method of Norplant removal that can easily be performed with use of high-resolution fluoroscopy with associated digital subtraction imaging.

Arm↗

PubMed1998

The amino-terminal domain of human STAT4. Overproduction, purification, and biophysical characterization.

The multifunctional signal transducer and activator of transcription (STAT) proteins relay signals from the cell membrane to the nucleus in response to cytokines and growth factors. STAT4 becomes activated when cells are treated with interleukin-12, a key cytokine regulator of cell-mediated immunity. Upon activation, dimers of STAT4 bind cooperatively to tandem interferon-gamma activation sequences (GAS elements) near the interferon-gamma gene and stimulate its transcription. The amino-terminal domain of STAT4 (STAT4(1-124)) is required for cooperative binding interactions between STAT4 dimers and activation of interferon-gamma transcription in response to interleukin-12. We have overproduced this domain of human STAT4 (hSTAT4(1-124)) in Escherichia coli and purified it to homogeneity for structural studies. The circular dichroism spectrum of hSTAT4(1-124) indicates that it has a well ordered conformation in solution. The translational diffusion constant of hSTAT4(1-124) was determined by nuclear magnetic resonance methods and found to be consistent with that of a dimer. The rotational correlation time (tauc) of hSTAT4(1-124) was estimated from 15N relaxation to be 16 ns; this value is consistent with a 29-kDa dimeric protein. These results, together with the number of signals observed in the two-dimensional 1H-15N heteronuclear single quantum coherence spectrum of uniformly 15N-labeled protein, indicate that hSTAT4(1-124) forms a stable, symmetric homodimer in solution. Cooperativity in native STAT4 probably results from a similar or identical interaction between the amino-terminal domains of adjacent dimers bound to DNA.

Amino Acid Sequence↗

PubMed1998

Removal of a Norplant implant located near a major nerve using interventional radiology-digital subtraction fluoroscopy.

Norplant implants can be removed easily, if inserted properly. When they are inserted deeply and can not be palpated, or if they are located close to the neurovascular structures of the upper arm, radiological guidance may be needed to locate and remove the implants without causing injury to the surrounding vital structures. Digital subtraction fluoroscopic guidance is helpful in removing deeply located contraceptive implants and those that are close to the neurovascular structures, where blind removal may result in injury to those structures. We describe a case in which an implant that was located close to a major nerve near the axilla was removed under digital subtraction fluoroscopic guidance.

Adult↗

PubMed1996

Removal of deeply inserted, nonpalpable levonorgestrel (Norplant) implants.

Deeply inserted, nonpalpable contraceptive implants can often be removed easily using 6-8 cm3 of 1% lidocaine and a single 1 cm incision. There is no need for suturing of the incision. The location of nonpalpable implants not retrieved by this procedure can be determined by a plain, soft tissue x-ray (standard AP and lateral and internal oblique; 45-55 kVP) of the area where the implants are inserted. Removal can then be accomplished several weeks later.

Analgesia↗

PubMed1995

Neurovascular injury during removal of levonorgestrel implants.

Injury to major neurovascular structures of the upper arm is a complication to be kept in mind, especially during difficult levonorgestrel implant removal. The risk of such an injury may be higher if the implants are inserted deeply over the brachial groove, where four major structures, namely, the basilic vein, the ulnar and median nerves, and the brachial artery, are located.

Arm↗

PubMed1994

The Emory method: a modified approach to Norplant implants removal.

Norplant implants were removed from fifty (50) patients using a modified approach to Norplant implant removal (Emory Method). Eighty-eight percent (88%) of the removals were accomplished in less than 10 minutes using this technique. The average time for removal of Norplant implants from 50 women included in the current study was 8 minutes. The Emory Method for Norplant implant removal includes three steps which are different from the technique developed by the Population Council. More anesthesia, a slightly longer incision and vigorous disruption of the tissue encapsulation surrounding the implants are recommended. The Emory Method is fast, safe and easy to perform. It has been successfully taught to over twenty-five clinicians.

Contraceptive Agents, Female↗

PubMedDate not supplied

Use of the intrauterine device by inner-city women.

OBJECTIVE: To examine the use, effectiveness, acceptability, and continuation rates of the copper T 380 A intrauterine device (IUD) among women attending an inner-city family planning clinic. DESIGN: A 1-year prospective cohort study. SETTING: The family planning clinic of Grady Memorial Hospital, which serves the inner-city indigent population of Fulton and Dekalb counties in metropolitan Atlanta, Ga. PARTICIPANTS: A total of 115 women with 1 or more live births who were in a mutually monogamous relationship for the previous year had the copper T 380 A IUD inserted between December 20, 1990, and June 28, 1991. MAIN OUTCOME MEASURES: Follow-up, consisting of history and a pelvic examination, was done 2, 6, and 12 months after IUD insertion to determine the status of the IUD and to detect any complications related to its use. At the end of the study, the continuation rates, reasons for removal, and complications related to IUD use were assessed. RESULTS: Thirty-seven women were unavailable for follow-up. Eight of those were seen in other clinics at Grady Memorial Hospital, but no mention was made of their IUD status. Fifty-six of the remaining 78 women were known to continue IUD use without any complications at the end of the 12 months. Among the 22 women known to have the IUD removed, 8 women cited no problems. Pelvic pain, menometrorrhagia, desire for permanent sterilization, and expulsion of the device were mentioned as reasons for other IUD removals. Pelvic inflammatory disease was not documented in any of the patients during the year of follow-up. CONCLUSION: With proper screening and counseling, the IUD may be used successfully in selected patients in inner-city family planning clinics.

Adolescent↗