Paradoxical relationship between frequency selectivity and threshold sensitivity during auditory-nerve fiber development.

The acquisition of adult-like frequency selectivity is generally assumed to be the tightly coupled to improvements in threshold sensitivity during cochlear development. In this study, frequency versus threshold (tuning) curves obtained from 1108 auditory-nerve fibers were used to investigate the relationship between tuning and threshold at characteristic frequency (CF) during postnatal development in kittens. At the earliest ages included in this study, sharpness was within the adult range, but thresholds were significantly higher than adult values. Tuning and thresholds improved along different exponential time courses that varied with CF. For units with CFs below 1 kHz, tuning curve slopes below CF matured earliest, followed by CF threshold, and then by slopes above CF. In contrast, for CFs above 1 kHz, the high-frequency slopes matured first, followed by threshold and then by slope below CF. One interpretation of these results is that tuning and thresholds are not tightly coupled in immature animals. Paradoxically, however, high-frequency slopes were correlated with threshold for individual units at all ages, suggesting that the relationship between tuning and threshold is maintained during development. This contradiction can be resolved by a developmental model that features a functional separation between cochlear nonlinearities and mechanical/electrical conversion.

LLETZ is an acceptable alternative to diagnostic cold-knife conization.

Large loop excision of the transformation zone (LLETZ) provides a pathologic specimen similar to a cold-knife cone (CKC) biopsy of the cervix. One hundred twenty women with indications for a cone biopsy were evaluated with LLETZ to determine if this procedure is an acceptable alternative to traditional cold-knife conization of the cervix. All patients had LLETZ performed in the clinic under local anesthesia. An average of 2.1 slices was required to remove the transformation zone. Coagulation artifact interfered with histologic diagnosis in only 1.8% of specimens. The number of slices taken during the LLETZ procedure significantly correlated with the amount of heat artifact in the pathology specimen (P = 0.02) and interfered with the ability of the pathologist to determine complete excision of dysplasia (P = 0.03). LLETZ is an acceptable alternative to diagnostic CKC and can offer a substantial cost savings. To facilitate histopathologic interpretation, every effort should be made to minimize the number of slices and to maintain orientation of the LLETZ specimen. Endocervical curettage performed after LLETZ can identify a group of patients who are at high risk for CIN recurrence.

Appraisal of the modalities used to evaluate an initial abnormal Papanicolaou smear.

OBJECTIVE: To examine the efficacy of the different modalities used to evaluate an initial abnormal Papanicolaou smear. METHODS: The study population comprised 214 nonpregnant women referred with a Papanicolaou smear diagnosis of cervical intraepithelial neoplasia. Each patient was evaluated by a repeat Papanicolaou smear, colposcopy, and colposcopically directed cervical biopsies. Immediate loop excision was performed to remove the entire transformation zone in all patients. Kappa statistics were calculated to determine agreement among the modalities, and logistic regression was used for determining relative risks (RR). RESULTS: There was 53% agreement between the initial and repeat Papanicolaou smears. When low-grade squamous intraepithelial lesion (SIL) was diagnosed by Papanicolaou smear, there was 89% agreement with the colposcopic impression. However, a colposcopic impression of high-grade SIL was found in only one-third of the women diagnosed with high-grade SIL by Papanicolaou smear. A comparison of the histology of the cervical biopsy and the loop specimen revealed 57% agreement. Univariate analysis indicated that each modality was able to predict the RR of high-grade dysplasia in the loop specimen at a statistical significance level of .05. A colposcopic impression of high-grade dysplasia conferred an RR of 7.43 (95% confidence interval [CI] 2.17-25.49) for high-grade dysplasia in the loop specimen. An initial Papanicolaou smear diagnosis of high-grade SIL did not contribute to the multivariate model for calculating the risk of high-grade dysplasia, as the RR was 1.6 (95% CI 0.68-3.81). CONCLUSION: Patients with an initial Papanicolaou smear showing low-grade SIL would benefit from a repeat Papanicolaou smear and colposcopically directed biopsies before proceeding with loop diathermy. In contrast, patients with a colposcopic impression of high-grade dysplasia combined with high-grade SIL on Papanicolaou smear appear to be candidates for immediate loop excision.

Responses of peripheral auditory neurons to two-tone stimuli during development: III. Rate facilitation.

Approximately 25% of peripheral auditory neurons having low characteristic frequencies (CFs) and broad tuning, and recorded from immature animals, responded to two-tone stimuli with increases in discharge rate greater than predicted by linear summation of the responses to probe tones (facilitation), in contrast to the two-tone suppression observed in adult animals and in more sharply tuned immature neurons. Facilitation was not seen after 81 gestational days and was not observed when test tones produced a substantial increase in rate when presented alone. The fact that some neural responses were facilitated under conditions of two-tone stimulation during the final stages of cochlear differentiation provides additional evidence that signal transduction is fundamentally different in neonatal kittens than in adults. A linear model of basilar membrane mechanics coupled to nonlinear neural processes is proposed which can account for the production of facilitation.

Prospective randomized trial of LLETZ versus laser ablation in patients with cervical intraepithelial neoplasia.

Three hundred seventy-five patients with CIN on referral Pap and with a distinct cervical lesion on colposcopy were prospectively randomized to treatment with LLETZ or to standard colposcopic evaluation with directed cervical biopsies, endocervical curettage, and laser ablation of the transformation zone for biopsy proven CIN. Of the 195 patients that randomized to treatment with LLETZ, 32.5% had no evidence of dysplasia, 26.5% had CIN 1, 17.3% had CIN 2, 22.7% had CIN 3, and 0.5% had microinvasive carcinoma on final histologic evaluation. Of the 180 patients randomized to laser ablation, initial cervical biopsies demonstrated no evidence of dysplasia in 52.8% of patients, CIN 1 in 22.0%, CIN 2 in 18.3%, and CIN 3 in 5.7%. Only 114 (63.3%) of the women in the laser group required therapy. Complications were comparable for each treatment arm. Only 6.7% of patients randomized to LLETZ and 4.4% with laser ablation had persistent CIN on follow-up Pap. LLETZ appears to be effective, well tolerated, and less expensive, but the cost savings advantage of LLETZ over laser ablation may not apply to patients with CIN 1 on referral Pap smear since many do not require treatment.

Contrast enema diagnosis of necrotizing enterocolitis.

Contrast enema was performed in a select group of 126 neonates with ambiguous diagnosis of necrotizing enterocolitis (NEC). Enema findings were compared with that on plain abdominal radiographs (AXR) and the clinical outcome. Thirty-one of the 34 patients with a discharge diagnosis of NEC were interpreted to have a positive contrast enema, and 91 of the 92 patients without a discharge diagnosis of NEC were interpreted to have a negative contrast enema. The AXR was interpreted as positive in 57 patients and as negative or indeterminate in 69. Not a single case of perforation was produced. Judicious use of contrast enema can improve specificity of diagnosis in cases with discordant clinical and plain radiographic findings.

Evaluation of the cerviscope as a screening instrument.

The cerviscope has been proposed as a screening tool for use in conjunction with the Papanicolaou smear as a system offering many of the same advantages as colposcopy and cytology. One hundred twenty-five patients were evaluated with the cerviscope who had been referred to this colposcopy clinic with a diagnosis of dysplasia. The purpose of this study was to evaluate the instrument's potential as a screening adjunct in the context of simultaneous evaluation by colposcopy. Thirty-nine percent (49 patients) were unevaluable due to technical problems (defective cervicogram, nonvisualized squamocolumnar junction). Significantly, 67% (26 patients) of the 39 patients reported as having negative cervicograms had a biopsy-proven dysplasia (19 mild, 4 moderate, 3 severe). By the chi 2 method, this is statistically significant (P less than 0.001).

Correlation between plasma and urine glucose in diabetes.

To determine whether semiquantitative glucose measurements of spot urine specimens accurately reflect prevailing plasma glucose levels, we compared reported levels from 400 second-voided urines to simultaneous plasma determinations from 246 adult diabetics. Quantitative urine levels and plasma glucose levels correlated. However, when semiquantitative urinary determinations were compared to plasma glucose stratified into 0 to 149, 150 to 199, and greater than 200 mg/dL, 75% of the urine samples associated with plasma levels from 150 to 199 mg/dL were negative by Diastix, and 16.5% of samples negative by Diastix were in the 200+ mg/dL plasma range. Only 9% of samples from 0 to 149 mg/dL showed any positive Diastix readings. Because of the low sensitivity of semiquantitative methods, we fell that, except for detection of marked hyperglycemia, spot urine glucose determinations are inadequate as the sole means of clinical assessment for management of diabetic patients. Home glucose monitoring may be a better alternative for follow-up of these patients.

Combined outpatient laparoscopic sterilization with therapeutic abortion.

Combined outpatient laparoscopic sterilization and therapeutic abortion were evaluated at Charlotte Memorial Hospital and Presbyterian Hospital. Two hundred and four patients underwent the procedure, which proved to be safe and effective, requiring only a brief hospital stay.

PIP: The safety of performing combined laparoscopic sterilization with therapeutic abortion was evaluated in an outpatient setting. During the 3-year study at Charlotte Memorial Hospital and Presbyterian Hospital, 204 cases of combined therapeutic abortion and laparoscopic tubal coagulation were performed in patients under 13-weeks gestation (mean, 9.4 weeks). Average age was 30.7 years, with 51% falling in the 30-39 year range. The mean surgical time from incision to end of anesthesia was 38 minutes. The mean hospitalization time from beginning of anesthesia to discharge from the outpatient department was 5 hours 20 minutes. No difference in complications with the single- or double-puncture method, nor with the endotracheal or nonendotracheal anesthesia, emerged from the statistics. 13 patients (6.3%) received antiemetics, and 15 (7.4%) were given oral medication for abdominal or shoulder pain. The only major complication occurred from uterine perforation during suction curettage. 1 pregnancy occurred after sterilization. The overall complication rate was 2.5% when both major and minor complications were included. Overnight observation was required for 11 cases (5.3%); 7 for patient convenience, anxiety, or abdominal discomfort and 4 for potentially serious complications which did not materialize.