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Biomedical subjects

D E Townsend

Publications and source records attributed to D E Townsend.

At least 19 recordsLinked to original sources
PubMed1995

Cloning of the mgtE Mg2+ transporter from Providencia stuartii and the distribution of mgtE in gram-negative and gram-positive bacteria.

The MM281 strain of Salmonella typhimurium possesses mutations in each of its three Mg2+ transport systems, requires 100 mM Mg2+ for growth, and was used to screen a genomic library from the gram-negative bacterium Providencia stuartii for clones that could restore the ability to grow without Mg2+ supplementation. The clones obtained also conferred sensitivity to Co2+, a phenotype similar to that seen with the S. typhimurium corA Mg2+ transport gene. The sequence of the cloned P. stuartii DNA revealed the presence of a single open reading frame, which was shown to express a protein with a gel molecular mass of 37 kDa in agreement with the deduced size of 34 kDa. Despite a phenotype similar to that of corA and the close phylogenetic relationship between P. stuartii and S. typhimurium, this new putative Mg2+ transporter lacks similarity to the CorA Mg2+ transporter and is instead homologous to MgtE, a newly discovered Mg2+ transport protein from the gram-positive bacterium Bacillus firmus OF4. The distribution of mgtE in bacteria was studied by Southern blot hybridization to PCR amplification products. In contrast to the ubiquity of the corA gene, which encodes the dominant constitutive Mg2+ influx system of bacteria, mgtE has a much more limited phylogenetic distribution.

Amino Acid Sequence↗
PubMed1993

Condylomata acuminata. Roles of different techniques of laser vaporization.

Eighty-four women with acuminate warts of the external genital tract were treated with two methods of laser vaporization. Patients were classified by lesion number and volume (1+, 2+, 3+). Thirty-three patients had only the lesions vaporized, whereas 51 had individual lesions vaporized followed by the "brushing" technique applied to the surrounding mucosa. Postoperative discomfort and pain were worse in those patients who had the brushing technique. The results were assessed colposcopically six to eight weeks postoperatively. Regardless of the method of laser vaporization, the majority of patients with extensive disease (2+ or 3+) had persistent lesions, although reduced in number in most instances. Patients with relatively few lesions (1+) had complete elimination of the warts whether or not brushing was employed. Based upon this study, reducing the burden of acuminate warts before laser vaporization is recommended.

Analysis of Variance↗
PubMed1993

Diagnostic and operative hysteroscopy in the management of persistent postmenopausal bleeding.

OBJECTIVE: To determine the cause and possible treatment of postmenopausal bleeding of 6 months' duration or longer. METHODS: One hundred ten women between the ages of 40-90 years with persistent postmenopausal bleeding were evaluated by diagnostic hysteroscopy and managed by operative hysteroscopy. All had endometrial sampling and/or office hysteroscopy before operative hysteroscopy. RESULTS: A benign organic cause was noted in 95 cases (polyps in 42 and submucous fibroids in 53). Thirteen women had no significant disease and two had an early adenocarcinoma. Resection of the polyps or myomas without ablation was performed in 45 women, and all but one were satisfied with the results of treatment. Resection and ablation with performed in the remaining 50 patients with organic causes, and all but one were satisfied with the results. Twelve of 13 women without organic causes were satisfied with their treatment. The two adenocarcinomas were early lesions, grade 1 without invasion, and were managed by simple hysterectomy. CONCLUSION: Diagnostic and operative hysteroscopy was effective in controlling postmenopausal bleeding of at least 6 months' duration. Almost 90% of the patients had either polyps or submucous fibroids as the primary cause of the bleeding. Resection alone and resection with ablation were equally effective in controlling the bleeding.

Adult↗
PubMed1993

Post-ablation-tubal sterilization syndrome.

OBJECTIVE: To determine the cause of unilateral or bilateral pelvic pain associated with vaginal spotting in women who had previously undergone tubal ligation followed by roller-ball endometrial ablation. METHODS: Women who had undergone previous tubal sterilization followed by rollerball endometrial ablation were evaluated laparoscopically and hysteroscopically when they presented with a symptom complex of intermittent vaginal bleeding associated with severe cramping pain in the lower abdomen. RESULTS: During a 1.5-year observation period, six women with the symptom complex had laparoscopy and hysteroscopy. In all cases, marked endometrial scarring was noted. In every case, the proximal portions of either one or both fallopian tubes were swollen, and two cases had the appearance of an early ectopic pregnancy. In the remaining cases, the fallopian tubes were rubbery and swollen to as much as twice normal size. Symptoms in five of six patients subsided after laparoscopic removal of the oviduct. CONCLUSION: It appears that women who have had a tubal sterilization followed by endometrial ablation are at risk of developing an ectopic-like symptom complex. Salpingectomy appears to be effective in relieving symptoms. Whether this represents a new syndrome or just an unusual association between tubal sterilization and endometrial ablation remains to be seen.

Abdominal Pain↗
PubMed1993

Tuboovarian abscesses after operative hysteroscopy.

Postoperative infection after operative hysteroscopy is uncommon. However, patients who have a past history of pelvic inflammatory disease appear to be at risk of developing such infections, including tuboovarian abscesses. Prophylactic antibiotics during operative hysteroscopy appear to be effective in preventing this problem.

Abscess↗
PubMed1992

Synchronous radiation and cytotoxic chemotherapy for locally advanced or recurrent squamous cancer of the vulva.

Between July 1987 and September 1991 a program of external beam radiation and synchronous, radiopotentiating chemotherapy was employed to treat 25 women with locoregionally advanced or locoregionally recurrent squamous cancer of the vulva. Of 18 previously untreated patients, 1 was Stage II, 10 were Stage III, 6 were Stage IVA, and 1 was Stage IVB. Reasons for patient referral for nonsurgical management included the presence of initially unresectable disease (5 patients), disease extent which would have necessitated partial or total exenteration if treated surgically (9 patients), disease extent predictive of inadequate surgical margins (less than 1 cm gross margin) if treated by less than exenterative surgery (8 patients), and severe comorbid illness precluding surgical management (3 patients). Complete clinical response was obtained in 16 of 18 previously untreated patients (89%) and in 4 of 7 patients with recurrent disease following vulvar surgery (57%). Of 20 patients achieving a complete clinical response, 3 patients have relapsed within the irradiated volume at 11, 38, and 48 months following completion of treatment. Fourteen patients remain alive and continuously cancer free from 2-52 months after completion of treatment (median follow-up 24 months). This experience suggests that initial management with radiation and chemotherapy may offer some patients with locally advanced squamous cancer of the vulva an alternative to exenterative surgery and may hold curative potential for some patients with surgically unresectable or medically inoperable disease.

Adolescent↗
PubMed1992

Proline transport in Staphylococcus aureus: a high-affinity system and a low-affinity system involved in osmoregulation.

L-Proline enhanced the growth of Staphylococcus aureus in high-osmotic-strength medium, i.e., it acted as an osmoprotectant. Study of the kinetics of L-[14C]proline uptake by S. aureus NCTC 8325 revealed high-affinity (Km = 1.7 microM; maximum rate of transport [Vmax] = 1.1 nmol/min/mg [dry weight]) and low-affinity (Km = 132 microM; Vmax = 22 nmol/min/mg [dry weight]) transport systems. Both systems were present in a proline prototrophic variant grown in the absence of proline, although the Vmax of the high-affinity system was three to five times higher than that of the high-affinity system in strain 8325. Both systems were dependent on Na+ for activity, and the high-affinity system was stimulated by lower concentrations of Na+ more than the low-affinity system. The proline transport activity of the low-affinity system was stimulated by increased osmotic strength. The high-affinity system was highly specific for L-proline, whereas the low-affinity system showed a broader substrate specificity. Glycine betaine did not compete with proline for uptake through either system. Inhibitor studies confirmed that proline uptake occurred via Na(+)-dependent systems and suggested the involvement of the proton motive force in creating an Na+ gradient. Hyperosmotic stress (upshock) of growing cultures led to a rapid and large uptake of L-[14C]proline that was not dependent on new protein synthesis. It is suggested that the low-affinity system is involved in adjusting to increased environmental osmolarity and that the high-affinity system may be involved in scavenging low concentrations of proline.

Biological Transport↗
PubMed1991

Vasopressin and operative hysteroscopy in the management of delayed postabortion and postpartum bleeding.

Two women, one with refractory postabortion hemorrhage and the other with refractory postpartum hemorrhage, were managed with vasopressin, operative hysteroscopy, and a dilute vasopressin pack. Both patients had been treated by standard methods (i.e., dilation and curettage) and both were being prepared for a surgical intervention procedure. It was decided in both cases to try to slow the bleeding by injection of vasopressin paracervically and then performance of operative hysteroscopy. In both cases, the injection of dilute vasopressin paracervically when coupled with operative hysteroscopy was quite effective in determining the cause of the bleeding and was instrumental in avoiding major operative procedures.

Abortion, Induced↗
PubMed1991

Vasopressin pack for treatment of bleeding after myoma resection.

In 17 women with refractory bleeding after myoma resection a dilute vasopressin pack was applied. Twenty units of vasopressin was diluted with 30 ml normal saline solution. A 1-inch new gauze pack was soaked in the dilute vasopressin and packed into the uteri of patients with bleeding from the beds of resected submucous myomas. The pack was left in place for no more than an hour. In none of the cases was there bleeding after the removal of the pack nor were there any side effects that could be attributed to the vasopressin.

Administration, Intravaginal↗
PubMed1990

"Rollerball" coagulation of the endometrium.

Menorrhagia was the primary complaint of 50 patients treated by "rollerball" electrocoagulation of the endometrium. All the patients in this series had failed surgical (D & C) and/or medical therapy and all had refused hysterectomy. The electrocoagulation was performed on an outpatient basis. Complications have been minimal with follow-up varying from 6-22 months. Amenorrhea was achieved in ten of the 25 women who were followed for at least 12 months. An additional ten patients have had monthly spotting and five have had light bleeding. None of the patients noted a return of their menorrhagia. In the other 25 patients bleeding could not be evaluated, as all received medroxyprogesterone after their ablation. The preliminary results suggest that "rollerball" electrocoagulation is a safe, economical, and effective method of eliminating or reducing menorrhagia.

Combined Modality Therapy↗
PubMed1987

The international spread of methicillin-resistant Staphylococcus aureus.

A genetic analysis of representative methicillin-resistant Staphylococcus aureus (MRSA) being isolated in London and Dublin hospitals has demonstrated that the epidemic strains from two London hospitals are different from the Dublin strains, but indistinguishable from the epidemic strains of eastern Australia. The possibility that some strains of MRSA are more likely than others to spread within hospitals is discussed.

Australia↗