Effects of time after deafening and implantation on guinea pig electrical detection thresholds.

Changes in detection threshold level as a function of time after deafening and implantation have been described previously in macaque [Pfingst, 1990] and human [Skinner et al., 1995] cochlear implant subjects. Characterization of the mechanisms underlying these changes will contribute to our understanding of the anatomical and physiological factors affecting electrical stimulus detection. In addition, understanding the time course of early threshold changes is essential to the interpretation of acute physiological studies of cochlear implants. To better characterize time-dependent threshold changes, we monitored changes in guinea pig psychophysical electrical detection thresholds with time after deafening and cochlear implantation. Threshold levels for 100 Hz sinusoidal bursts were initially unstable over the first 30 days post-surgery (DPS), after which thresholds stabilized. At longer intervals (>100 DPS), increases (>10 dB) in threshold level were observed for 100 Hz sinusoids in three of 11 cases. These changes were transient in one case and long-term in two cases. The time course of threshold change, both early and late, could not be explained on the basis of changes in spiral ganglion cell survival. The guinea pig seems to be an ideal preparation for studies of this nature, because threshold changes are similar in type, but accelerated in time course, relative to those observed in primates.

The adult respiratory distress syndrome after dextran infusion as an antithrombotic agent in free TRAM flap breast reconstruction.

Adult respiratory distress syndrome occurred in a patient who had received dextran as a routine antithrombotic agent during and after free TRAM breast reconstruction. Although most patients who receive dextran have no adverse reaction, particularly after hapten inhibition by dextran 1 infusion, the serious nature of this complication in an elective operation calls into question the continuing routine use of dextran in microsurgery.

Dermal autografts for fascial repair after TRAM flap harvest.

To find an alternative to synthetic mesh closure of abdominal fascial defects after transverse rectus abdominis musculocutaneous (TRAM) flap harvest, dermal autografts were removed from tissue to be discarded and used for fascial closure. Dermal grafts have been used for herniorrhaphy and fascial repair after TRAM harvest previously, but have never been systematically studied. The dermal autograft technique was used in 24 patients to repair or reinforce anterior rectus sheath or external oblique fascia after TRAM harvest for breast reconstruction. During the same period, 25 other patients underwent TRAM breast reconstruction with abdominal wall closure by other methods. All patients were followed by serial physical examinations given by the operating surgeon. Average follow-up in the dermal autograft group was 12.6 versus 12.0 months in the second group. In the dermal autograft group, two patients complained of bulging of the anterior abdominal wall; one developed a true hernia, away from the location of the dermal autograft. In the second group, two patients experienced bulging. Wounds and infectious complications were similar in both groups. Dermal autografts are a useful alternative to mesh repair or direct closure of fascial defects after TRAM flap harvest.

Skin-sparing mastectomy and immediate reconstruction: oncologic risks and aesthetic results in patients with early-stage breast cancer.

Skin-sparing mastectomy has been advocated as an oncologically safe approach for the management of patients with early-stage breast cancer that minimizes deformity and improves cosmesis through preservation of the skin envelope of the breast. Because chest wall skin is the most frequent site of local failure after mastectomy, concerns have been raised that inadequate skin excision could result in an increased risk of local recurrence. Precise borders of the skin resection have not been well established, and long-term local recurrence rates after skin-sparing mastectomy are not known. The purpose of this study was to evaluate the oncologic safety and aesthetic results for skin-sparing mastectomy and immediate breast reconstruction with a latissimus dorsi myocutaneous flap and saline breast prosthesis. Fifty-one patients with early-stage breast cancer (26 with ductal carcinoma in situ and 25 with invasive carcinoma) undergoing primary mastectomy and immediate reconstruction with a latissimus flap were studied from 1991 through 1994. For 32 consecutive patients, skin-sparing mastectomy was defined as a 5-mm margin of skin designed around the border of the nipple-areolar complex. After the mastectomy, biopsies were obtained from the remaining native skin flap edges. Patients were followed for 44.8 months. Histologic examination of 114 native skin flap biopsy specimens failed to demonstrate breast ducts in the dermis of any of the 32 consecutive patients studied. One of 26 patients with ductal carcinoma in situ had metastases to the skin of the lateral chest wall and back. Four other patients, one with stage I disease and three with stage II-B disease, had recurrent breast carcinoma. The stage I patient had a local recurrence in the subcutaneous tissues near the mastectomy specimen. Two patients suffered axillary relapse, and one had distant metastases to the spine. The findings of this study support the technique of skin-sparing mastectomy as an oncologically safe one, based on an absence of breast ductal epithelium at the margins of the native skin flaps and a local recurrence rate of 2 percent after 45 months of follow-up. Although these results need to be confirmed with greater numbers of patients and longer follow-up, skin-sparing mastectomy and immediate breast reconstruction may be considered an excellent alternative treatment to breast conservation for patients with ductal carcinoma in situ and early-stage invasive breast cancer.

Breast infarction after internal mammary artery harvest in a patient with calciphylaxis.

The use of the internal mammary artery during coronary artery bypass grafting is commonplace. Complications associated with the harvest of the internal mammary artery have predominantly been wound related. These range from skin dehiscence to complete avascular necrosis of the sternum. This report documents complete ischemic necrosis of a breast in a patient with end-stage renal disease and a history of calciphylaxis, after the harvest of an internal mammary artery.

11BetaOH-progesterone affects vascular glucocorticoid metabolism and contractile response.

Vascular smooth muscle (VSM) contains a bidirectional isoform of 11beta-hydroxysteroid dehydrogenase (11beta-HSD), the enzyme that can metabolize endogenous glucocorticoids to their respective 11-dehydro derivatives. 11BetaOH-progesterone (11betaOH-P), a compound that can be produced in vivo, is as potent or more potent than licorice derivatives in inhibiting renal and hepatic 11beta-HSD. When studied in homogenates prepared from primary cultures of rat VSM, 11betaOH-P and its derivative, 11-keto-progesterone (11-keto-P), proved to be potent, directionally specific inhibitors of vascular 11beta-HSD. 11BetaOH-P selectively inhibited the forward dehydrogenase reaction (corticosterone-->11-dehydrocorticosterone), whereas 11-keto-P selectively blocked the reverse oxidoreductase reaction. To test the physiological effects, vascular rings were prepared from rat aorta. Rings were incubated in culture media containing either a submaximal concentration of corticosterone (10 nmol/L), 11-dehydrocorticosterone (100 nmol/L), 11betaOH-P (1 micromol/L), 11-keto-P (1 micromol/L), or a combination of glucocorticoid and inhibitor for 24 hours. After the 24-hour incubation, rings were briefly stimulated sequentially with phenylephrine (10 nmol/L to 1 micromol/L) and angiotensin II (1 micromol/L). The immediate contractile response in rings incubated with both corticosterone and 11betaOH-P was greater than in rings previously incubated with either the corticosterone or 11betaOH-P alone (eg, response to 100 nmol/L phenylephrine in milligrams of force, mean+/-SE: corticosterone, 728+/-56, n=9; 11betaOH-P, 325+/-105, n=4; both, 1132+/-122, n=8; corticosterone versus both, P<.01). In contrast, the immediate contractile responses to phenylephrine and to angiotensin II were attenuated in rings exposed previously to both 11-dehydrocorticosterone and 11-keto-P. Thus, 11betaOH-P and 11-keto-P (and possibly structurally similar compounds) alter the vascular effects of glucocorticoids and may play a role in glucocorticoid-induced hypertension.

Chromosome 2 hypersensitivity and clonal development in murine radiation acute myeloid leukaemia.

Acute myeloid leukaemias induced by ionizing radiation in mouse are characterized by chromosome (chr) 2 aberrations. While it is known that chr 2 aberrations form early and in abundance post-irradiation, unequivocal evidence for hypersensitivity of chr 2 in the first post-irradiation mitoses is lacking. Here it is established that chromosomal aberrations detected in bone marrow cells by chromosome painting are induced in all mice at an approximately 2-fold greater frequency in chr 2 by comparison with chrs 1 and 3 at 24 and 48 h following in vivo whole-body X-irradiation. Long-term follow up studies (to 15 months post-irradiation) indicated that chromosomal hypersensitivity is accounted for largely by the existence of hot-spots for aberration formation on sensitive chromosomes. Analysis of clonal developments suggested that chr 2 aberrant clones are selected for entry into the proliferating bone marrow cell compartment in preference to cells with other aberrations and that these clones in general have a higher proliferative potential. However, neither the induction of chr 2 aberrations nor the presence of a chr 2 aberrant clone specifically predict the development of AML in an individual irradiated mouse. Nonetheless these events or sub-groups of these events are necessary for AML development.

Selective inhibition of sheep kidney 11 beta-hydroxysteroid dehydrogenase isoform 2 activity by 5 alpha-reduced (but not 5 beta) derivatives of adrenocorticosteroids.

We have previously reported that 5 alpha and 5 beta pathways of steroid metabolism are controlled in vivo by dietary Na+ and glycyrrhetinic acid, see Gorsline et al. 1988; Latif et al. 1990. The present investigations provide evidence supporting the suggestion that endogenous substances may regulate the glucocorticoid inactivating isoenzymes, 11 beta-HSD (hydroxysteroid dehydrogenase) 1 (liver) and 11 beta-HSD2 (kidney). The activity of 11 beta-HSD is impaired in essential hypertension, following licorice ingestion, and in patients with apparent mineralocorticoid excess where 11 beta-HSD2 is particularly affected. In all three conditions, excretion of the less common 5 alpha metabolites is elevated in urine. We now report on the differential abilities of a series of Ring A reduced (5 alpha and 5 beta) adrenocorticosteroid and progesterone metabolites to inhibit these isoenzymes. Using liver microsomes with NADP+ as co-factor (11 beta-HSD1), and sheep kidney microsomes with NAD+ as co-factor (11 beta-HSD2), we have systematically investigated the abilities of a number of adrenocorticosteroids and their derivatives to inhibit the individual isoforms of 11 beta-HSD. A striking feature is the differential sensitivity of the two isoenzymes to inhibition by 5 alpha and 5 beta derivatives. 11 beta-HSD1 is inhibited by both 5 alpha and certain 5 beta derivatives. 11 beta-HSD-2 was selectively inhibited only by 5 alpha derivatives: 5 beta derivatives were without inhibitory activity toward this isoform of 11 beta-HSD. These results indicate the importance of the structural conformation of the A and B Rings in conferring specific inhibitory properties on these compounds. In addition, we discuss the effects of additions or substitutions of other functional groups on the inhibitory potency of these steroid molecules against 11 beta-HSD1 and 11 beta-HSD2.

Role of telomeric sequences in murine radiation-induced myeloid leukaemia.

A previous study indicated that a highly inbred CBA/H mouse colony contained four genotypic variants for telomere-like repeat (TLR) sequence arrays and that one variant subpopulation that constituted 20% of the colony contributed the vast majority (> 90%) of radiation-induced acute myeloid leukaemias (AMLs). Through screening of a satellite CBA/H colony and rescreening of the original colony, we show that, whereas germline telomere sequence polymorphism is frequent in CBA/H mice, there is no genetic link between a specific TLR locus variant and susceptibility to AML. Studies on telomere-hybridising fragments between 200 bp and 150 kb revealed that the germline telomere mutation frequency was highest for restriction fragments > 50 kb. The hypervariability of these high-molecular-weight fragments resulted in each CBA/H mouse from the highly inbred colony having a different genotype. Although it was not possible to ascribe a specific somatic telomere mutation to AML development, telomere rearrangements were common in induced AMLs. Some terminal telomere-hybridising restriction fragments were shortened in AML samples in comparison with normal tissue, but, insofar as the reduction in size was relatively small, it seems unlikely that telomere erosion is a major contributor to the molecular pathology of murine radiation-induced AML.

Comparison of primer sets for detection of fecal and ocular adenovirus infection using the polymerase chain reaction.

Adenoviruses of subgenus F (types 40 and 41) cause infantile gastroenteritis and adenoviruses principally of types 1-7 are found in feces during respiratory or generalized infections. Adenoviruses (mostly types 3, 4, 8, 19, or 37) are also linked with follicular or epidemic conjunctivitis. The diagnostic efficiency of the polymerase chain reaction (PCR) for adenoviruses was assessed using genus-reactive primers H1 and H2 or JCH1 and JCH2 or subgenus F-specific primers F1a and F2a. With diarrheal stool specimens containing subgenus F adenoviruses, F1a/F2a PCR achieved at least as high a positivity rate (75/76 [99%]) as electron microscopy (72/76 [95%]) and was more sensitive than polyclonal antibody-based immune electron microscopy (IEM) for subgenus identification (75/76 [99%] vs. 66/76 [87%], P = 0.008). Twenty-three subgenus F strains untypeable by monoclonal antibody-based IEM were typed as 40 (n = 4) or 41 (n = 19) by Hha I digestion of the PCR product. The genus-reactive primer pairs provided DNA amplification assays of generally equal efficiency on conjunctival swab specimens though possible nucleic acid degradation in DNA extracts during storage could have meant that JCH1/JCH2 PCR was truly the more sensitive. The use of either genus-reactive primer set on fecal specimens cannot be recommended because, although the positivity rates with subgenus F PCR positive specimens were high (70/75 [93%] for H1 and H2, 14/15 [93%] for JCH1 and JCH2), the detection rates were disappointing with similar specimens yielding nonsubgenus F adenoviruses.

Polymerase chain reaction for rapid diagnosis of respiratory adenovirus infection.

Endemic (type 1, 2, 5 and 6) and epidemic (type 3, 4 and 7) respiratory adenovirus infections are associated with upper respiratory tract symptoms, pharyngoconjunctival fever, and pneumonia. Improved methods of diagnosis are needed, particularly in immunocompromized patients. We examined 93 throat swabs or nasopharyngeal aspirates from patients with acute respiratory disease using virus isolation and an adenovirus-specific polymerase chain reaction (PCR) based on consensus primers H1 and H2 derived from the hexon region DNA sequences of serotypes 2 and 5. Specimens which yielded viruses other than adenovirus in cell culture (n = 23) or which were negative for infectious viruses (n = 25) were negative in the PCR. The sensitivity of DNA amplification was 76% (34/45) in comparison with virus culture, being markedly lower with subgenus B (types 3 and 7) strains than with subgenus C (type 1, 2, 5 and 6) isolates (8/16 (50%)) vs. 26/28 (93%). P = 0.004) despite the use of a low annealing temperature to maximize detection of adenoviruses belonging to subgenera other than C. Of the 11 samples falsely negative in a single-round PCR but yielding adenovirus type 1 (n = 1), type 2 (n = 1). type 3 (n = 7), type 7 (n = 1), or untyped isolates (n = 1) in cell culture, nine (82%) gave positive results after nested DNA amplification. Possible approaches to further improving the performance of adenovirus PCR with respiratory specimens are discussed.

Multiplex polymerase chain reaction for adenovirus and herpes simplex virus in eye swabs.

Adenoviruses and herpes simplex virus (HSV) can cause clinically indistinguishable episodes of acute eye disease. Adenovirus infection is associated with nosocomial outbreaks and HSV may result in episodes of recurrent ocular inflammation. In a comparison of multiplex PCR for the two viral DNAs and virus isolation in cell culture, identical results were obtained for 18 of 20 specimens (positive for adenovirus in 5, HSV in 5, and negative in 8). One specimen was falsely negative for each viral DNA. Inclusion of human beta-globin primers in the adenovirus-HSV reaction was precluded by a consequential 10--100-fold reduction in sensitivity for the two viral targets and by the failure of beta-globin DNA amplification at the annealing temperature (45 degrees C) required to ensure detection of adenoviruses of serotypes 7 and 11 with the selected adenovirus primers. A single-target beta-globin PCR gave positive results with 19 of the 20 specimens prepared by treatment with proteinase K lysis buffer, indicating the effectiveness of this simple DNA extraction procedure. Nonetheless, the availability of effective antiviral therapy for HSV made monitoring for extraction failure using human primers crucial to avoid false-negative results for HSV DNA. Adenovirus-HSV PCR has considerable potential for the rapid diagnosis of viral eye disease particularly if beta-globin primers can be included in the reaction.

Pathogenesis of calciphylaxis: study of three cases with literature review.

Calciphylaxis is characterized by ischemic necrosis, primarily of skin. The early phase of the ischemia has not been studied, and the pathogenesis is uncertain. In this study of early calciphylaxis, the vessels responsible for the ischemia seem to be within the material available for microscopic review, and the various stenosing vascular lesions are quantified. A distinctive and previously described small vessel calcification with superimposed endovascular fibrosis is most common, and is much more frequent than two other lesions proposed to cause the ischemia (thrombosis and global calcific obliteration). The calcified stenotic vessels average 100 microns in diameter. Calcification precedes the endovascular fibrosis. Vessels with early endovascular fibroblastic activation are found statistically to be strongly associated with the presence of a giant cell reaction. This endovascular giant cell reaction has not been previously described in calciphylaxis. Two additional cases show similar findings. The histology resembles the reaction to calcium in a variety of other extraosseous calcification syndromes, for example, pseudogout, as if calciphylaxis were an endovascular form of calcium crystal-induced inflammatory disease. The literature is reviewed, and the clinicopathologic, radiographic, and therapeutic implications are discussed.

Polymerase chain reaction for rapid detection of ocular adenovirus infection.

Adenoviruses are associated with endemic and epidemic acute conjunctivitis, large nosocomial outbreaks reflecting virus transmission on unwashed hands or inadequately sterilised ophthalmic instruments. The polymerase chain reaction (PCR) proved more sensitive than antigen detection by immune dot-blot test for the rapid diagnosis of ocular adenovirus infection (sensitivities in a retrospective study 112/123 (91%) versus 72/123 (59%), P < 0.001). Indeed, in a prospective comparison, DNA amplification and virus isolation generated similar numbers of positive results (34 versus 32), though five PCR positive results were possibly false positives. The sensitivity of the PCR was largely independent of adenovirus subgenus or serotype, though reduced sensitivity with subgenus B strains could not be excluded. Specimen preparation for DNA amplification using a simple lysis buffer proved more effective than phenol-chloroform extraction. The immune dot-blot test gave unavoidable false positive results, but with the PCR this problem could be minimized by technical modifications. The PCR could replace antigen detection and virus isolation as the initial test for adenoviruses in conjunctival swabs, with cell culture only being retained for adenovirus serotyping in PCR positive specimens and for other viruses such as herpes simplex.

11 alpha- and 11 beta-hydroxyprogesterone, potent inhibitors of 11 beta-hydroxysteroid dehydrogenase (isoforms 1 and 2), confer marked mineralocorticoid activity on corticosterone in the ADX rat.

The effects of 11 alpha- and 11 beta-hydroxyprogesterone (11 alpha-OHP, 11 beta-OHP), on the activity of the glucocorticoid inactivating enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) were studied. 11 alpha-OHP and 11 beta-OHP were potent inhibitors of both 11 beta-HSD1 in rat liver microsomes and 11 beta-HSD2 in lysates of JEG-3 cells, a human choriocarcinoma cell line. In addition, both progesterone metabolites were markedly potent in conferring mineralocorticoid activity upon B in the adrenalectomized rat. These results provide insight into the structural properties required of inhibitors of 11 beta-HSD activity and indicate a possible role for endogenous 11 beta-HSD inhibitors in the regulation of glucocorticoid-induced Na+ retention.

Prospective study of adenovirus antigen detection in eye swabs by radioimmune dot-blot.

Rapid laboratory diagnosis of ocular adenovirus infection is crucial in the containment of nosocomial transmission of the virus. In a large prospective study of adenovirus assay in eye swabs, antigen detection by radioimmune dot-blot (turnaround time 72 hours) achieved a sensitivity of 67% (239/355) and a specificity of 93% (3065/3285) in comparison with virus culture (median turnaround time 14 days). When specimens weakly reactive for adenovirus antigen, or equally reactive for both adenovirus antigen and Chlamydia trachomatis antigen, were considered falsely reactive in the adenovirus test, the sensitivity of the latter was reduced and false positive reactions were only marginally less frequent. The radioimmune dot-blot provides a more rapid diagnosis of ocular adenovirus infection than virus culture, but the high risk of false negative and in particular false positive results limits its clinical utility.