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Biomedical subjects

N Johnson

Publications and source records attributed to N Johnson.

At least 217 records · Page 12Linked to original sources
PubMed1991

Experience with tissue expansion vaginoplasty.

In vaginal agenesis, a vagina can be treated by tissue expansion vaginoplasty. We have performed 17 such procedures. One procedure was abandoned because of infection of the temporary implant. In four women the first stage had to be repeated: in one the implant was placed too superficially, in another it did not provide adequate expansion, in a further instance the implant became infected and the fourth woman received a surgical wound to her labia. The second stage was successful in all 16 women who now have a vagina lined with viable epithelium. The vaginal length was satisfactory in all but one. Two women complained of a vaginal discharge due to hair at the vaginal vault, two women developed postoperative haematomas and one experienced introital stenosis. The disadvantage of the procedure is that it requires two operative stages and involves a prolonged hospital stay but it is not technically complex and results in a full length vagina that does not require dilatation.

Adolescent↗
PubMed1991

The free-flap vaginoplasty; a new surgical procedure for the treatment of vaginal agenesis.

The ideal operation for a young woman born without a vagina would be a one stage procedure, creating a functionally normal vagina without cosmetically unattractive scars, without the need for subsequent dilatation, stents or obturators. This goal was achieved with a free flap vaginoplasty using a full thickness skin graft taken from the scapula region. The blood supply of the graft was maintained by microvascular anastomosis of the graft pedicles to vessels in the groin. The operation has been performed in three young women who were born with uterine hypoplasia and vaginal agenesis. We experienced no unexpected complications, the procedure was well tolerated and left our patients with a good length, fully functional vagina. However, the operation is a major undertaking and needs to be performed by those with expertise in plastic surgery as well as in gynaecology.

Adolescent↗
PubMed1991

Effect of cervical traction with a tenaculum on the uterocervical angle.

The effect of cervical traction on the uterocervical angle was measured radiographically in 24 women undergoing diagnostic curettage. A radio-opaque guidewire was inserted through the cervical canal into the uterine cavity and a lateral pelvic X-ray taken before and after traction. The traction force was measured with a spring-balance attached to the tenaculum. Cervical traction in a caudal direction (force 2 N) reduced the median uterocervical angle, from 75 degrees to 10 degrees (P = 0.001). Moderate cervical traction straightens the uterus and the routine use of a tenaculum theoretically makes insertion of an intrauterine device safer and the passage of an embryo transfer catheter less traumatic.

Cervix Uteri↗
PubMed1991

At what level of collective equipoise does a clinical trial become ethical?

It has often been argued that if a clinician cannot decide which of two treatments to offer, a trial may be ethical, but it is unethical if she/he has a preference. Since individual clinicians usually have a preference, most trials could be judged unethical according to this line of argument. A recent important article in the New England Journal of Medicine argued that individual preferences are not as important as the collective uncertainty of informed clinicians. If clinicians are equally divided, there is a state of collective equipoise and a trial is ethical. However, clinicians will seldom be exactly equally divided. We conducted an ethometric study to find out how much collective equipoise can be disturbed before the potential subjects in a trial think that it is unethical. Half of our subjects perceived a trial as unethical when equipoise was disturbed beyond 70:30. In other words, when 70 per cent of experts favour one treatment, 50 per cent of subjects would prefer that treatment to be administered rather than subjected to critical assessment. When equipoise is disturbed beyond 80:20, less than 3 per cent of subjects would consider human trials morally justifiable.

Aged↗
PubMed1991

Brainstem vascular accidents and cranial arteritis.

Cranial Arteritis (Giant Cell Arteritis) is a clinical diagnosis supported by a raised erythrocyte sedimentation rate (ESR) and if required confirmed by a temporal artery biopsy. This case reports on an unusual presentation where a delay in the diagnosis resulted in visual impairment, illustrating the need for awareness of diagnosis in acute strokes in the elderly.

Aged↗
PubMed1991

Auditory evoked potentials in panic disorder.

Neuroimaging studies of behavioral-induced anxiety in non-patients and of lactate-induced anxiety in panic disorder patients have indicated that normal and pathological anxiety may share a common pathway involving the temporal poles. As panic-related anxiety may reflect faulty temporopolar evaluative processing of input, the objective of this study was to examine sensory reactivity in panic disorder patients via scalp recordings of the late auditory evoked 'vertex' potential (LAEP) which appears to have a predominantly temporal lobe origin. Twelve patients diagnosed according to DSM-III criteria as panic disorder and ten normal controls served as subjects in this study. EEG was recorded from 16 scalp sites using a monopolar fronto-occipital derivation and LAEPs were separately averaged in response to four acoustic intensities. Analysis focused on group and electrode-site differences in the negative (N1) and positive (P2) component amplitudes of the LAEPs. Panic disorder patients were found to exhibit significantly larger N1 amplitudes across all stimulus intensities and across all recording sites. No significant group differences were observed with P2. Although the results provide indirect support for a temporal focus, other modulating influences must be considered in data interpretation.

Adult↗
PubMed1991

The accuracy of fetal pulse oximetry in the second stage of labour.

The aim of this study is to assess the accuracy of fetal monitoring with pulse oximetry at delivery. The pulse oximetry reading from the fetus at delivery was compared to fetal condition at birth. There is poor correlation between fetal scalp oximetry readings at delivery and fetal condition (Apgar scores), umbilical venous or arterial blood gas analysis or pH. Although there are good theoretical reasons why the correlation should not be perfect, the wide deviation from expected values suggest that readings taken during delivery are particularly prone to errors. Examination of the unprocessed photodetector signal during the second stage of labour reveals considerable movement interference. The signal may also be affected by congestion and transmitted venous pulsation in the scalp as the head crowns. The current generation of reflectance pulse oximeters can predict fetal hypoxemia during labour but a single reading during delivery is subject to too much movement interference to produce useful data.

Cardiotocography↗
PubMed1990

Effect of mifepristone on dilatation of the pregnant and non-pregnant cervix.

The effect of the progesterone antagonist mifepristone on the cervix was investigated in two randomised double-blind placebo-controlled trials, the first in 30 women undergoing first trimester surgical termination of pregnancy and the second in 30 non-pregnant premenopausal women. 600 mg mifepristone, given orally 48 h before surgery, increased the mean preoperative cervical dilatation in both pregnant and non-pregnant treatment groups and also reduced the force required to dilate the pregnant and non-pregnant cervix.

Administration, Oral↗
PubMed1990

Could antiprogesterones be used as alternative cervical ripening agents?

We measured the effect of a progesterone antagonist on the pregnant cervix with a custom-built cervicometer. The change in cervical diameter was studied in 11 pregnant patients after oral administration of 600 mg of RU-486. In all cases RU-486 ripened the cervix (p = 0.0007). The average increase in diameter was 13% (95% confidence limits, 10% to 16%).

Adult↗
PubMed1990

The correlation between dysmenorrhea and the pain experienced during laser ablation of a cervical lesion.

Twenty women undergoing colposcopically directed laser evaporation of a cervical intraepithelial neoplastic (CIN) lesion were recruited. Using a linear analog scale they scored the pain associated with a normal period when not using contraception. Under standardized conditions and without any analgesia or local anesthesia their transformation zone was ablated to a depth of approximately 6 mm by an independent operator. Pain was assessed 10 min after the procedure by the same technique as that used for the measurement of dysmenorrhea. There is a direct correlation (r = 0.7) between the discomfort of dysmenorrhea and discomfort at colposcopy. This allows the operating colposcopist to predict which patients are most likely to experience discomfort during laser evaporation of a cervical lesion.

Dysmenorrhea↗
PubMed1990

A new way to expose endocervical lesions at colposcopy.

If there are atypical cells on a cytological smear and if the squamo-columnar junction can not be visualized during a colposcopic examination, then in order to exclude an early invasive cancer in the nonvisualized area within the endocervix it is mandatory to perform a diagnostic cone biopsy. A woman with abnormal cervical cytology and an unsatisfactory colposcopic examination who refused a cone biopsy was offered Lamicel in an attempt to expose the entire transformation zone. After 4 hr the sponge was removed and colposcopy repeated. The lesion and the squamo-columnar junction was then fully visible and she was spared a cone biopsy.

Adult↗
PubMed1990

Computerized automation of clinical trials.

Over the past decade computers have revolutionized medical record systems. Data is now legible, organized and easily retrievable. The next decade will see a revolution in the way large multi-centre clinical trials are carried out. Computerized automation of trials improves compliance with the protocol, identifies deviations from the randomization system and reduces missing and erroneous data. Computerization also improves recruitment and eliminates mistakes during data transfer. All of these proven advantages are bought for a fraction of the cost of the investigators' time.

Clinical Trials as Topic↗
PubMed1990

Computer-aided clinical management: microscopic cancer of the ectocervix.

The main value of decision analysis is that it makes the trade-offs involved in a decision explicit. When depth of invasion is less than 3 mm with no vascular or lymphatic involvement, the risk of spread is so low that radical surgery is not warranted. When the lesion involves lymphatics but does not penetrate the basement membrane more than 1 mm, conservative therapy is still recommended if the operative mortality rate of radical treatment is at least 3.5 per 1000. However, in units with a low operative mortality rate, radical treatment offers the greatest survival advantage provided that fertility is not an issue. These statements refer only to optimizing survival chances and the decision is one of probabilistic dominance where correct treatment is determined entirely by probabilities rather than utility. For a young potential mother who accepts some risk to preserve fertility, the situation is different. Conservative therapy may be preferable despite lymphatic or vascular involvement provided that there is no more than 1 mm depth of invasion. Where invasion exceeds 5 mm, or where it exceeds 3 mm with vascular involvement, the risk of spread increases exponentially, and there must be very few patients for whom conservative therapy is appropriate.

Decision Trees↗