Vocal fold proteoglycans and their influence on biomechanics

OBJECTIVE/HYPOTHESIS

To examine the interstitial proteins of the vocal fold and their influence on the biomechanical properties of that tissue.

STUDY DESIGN

Anatomic study of the lamina propria of human cadaveric vocal folds combined with some viscosity testing.

METHODS

Identification of proteoglycans is performed with histochemical staining. Quantitative analysis is performed using an image analysis system. A rheometer is used for viscosity testing. Three-dimensional rendering program is used for the computer images.

RESULTS

Proteoglycans play an important role in tissue biomechanics. Hyaluronic acid is a key molecule that affects viscosity.

DISCUSSION

The proteoglycans of the lamina propria have important biological and biomechanical effects. The role of hyaluronic acid in determining tissue viscosity is emphasized. Viscosity, its effect on phonatory threshold pressure and energy expended due to phonation is discussed.

CONCLUSION

Proteoglycans, particularly hyaluronic acid, play important roles in determining biomechanical properties of tissue oscillation. Future research will likely make these proteins of important therapeutic interest.

Defective anticarbohydrate antibody responses to naturally occurring bacteria following bone marrow transplantation

The long-term recipients of allogeneic bone marrow transplantation (BMT) are at an increased risk of death due to bacterial infections. We evaluated the anticarbohydrate antibody responses of BMT recipients to a naturally occurring bacterial carbohydrate, polyribose phosphate (PRP). The recipients of autologous BMT achieved protective anti-PRP levels (>100 ng/mL) by 3 years after transplantation, with a pattern consistent with a recapitulation of the ontogeny of anticarbohydrate antibody responses. None of the six recipients of unrelated BMT who were off immunosuppressive therapy had protective anti-PRP levels, though their response to a protein antigen (tetanus toxoid) was normal. Of 48 recipients of histocompatible BMT, 22 (46%) had protective anti-PRP antibody levels, whereas 13 (27%) recipients who were >3 years post-BMT did not have protective levels. Therefore, all unrelated recipients and a significant proportion of histocompatible recipients without clinical graft-vs.-host disease had persistent and prolonged defects in their capacity to produce antibodies to naturally occurring bacterial carbohydrate antigens. These results suggest that allogeneic BMT recipients should be longitudinally evaluated for their anticarbohydrate antibody responses and that patients with defective antibody responses should receive prophylactic antibiotics or replacement immunoglobulin therapy or both to reduce their risk of late bacterial infections.

Ocular surface neoplasia masquerading as chronic blepharoconjunctivitis

PURPOSE

To present the clinical characteristics and difficulties in the diagnosis of various ocular surface malignancies mimicking features of chronic blepharoconjunctivitis and to summarize the current therapeutic approach and prognosis of patients.

METHODS

Six patients with slowly evolving signs of persistent inflammation underwent a conjunctival biopsy after a prolonged course of medical treatment. The medical records of the patients were reviewed.

RESULTS

Histopathologic examination of the biopsy specimens revealed intraepithelial squamous neoplasia (one patient), invasive squamous cell carcinoma (one patient), sebaceous carcinoma (two patients), and conjunctival lymphoma (two patients).

CONCLUSION

Although uncommon, ocular surface malignancies may involve the conjunctiva diffusely and present as chronic conjunctivitis. A high index of suspicion and an early histopathologic examination are essential to not delay diagnosis.

Evaluation of the value of an observation ward in an emergency department

A prospective study was undertaken to describe the pattern of utilization of an observation ward in an emergency department (ED). During a 1-month study period, the following data were collected for all patients admitted to the observation ward: (1) patient demographics, (2) purpose of observation, (3) interventions at the observation ward, (4) disposal destinations, (5) disposal diagnosis, (6) outcome categories, and (7) duration of stay. A total of 12188 patients attended our ED and 1042 (8.51%) patients were admitted into the observation ward. An average of 34 patients was admitted into the observation ward each day. The age of the patients ranged from neonates to 94 years (mean age of 45.7 years, +/-25.7 SD). Sex distribution was almost equal. The diagnostic evaluation group was the largest (58%) followed by short-term therapy (38%) and psychosocial problems (3.5%). Of the 554 patients with a disposal diagnosis, 350 (59%) had their diagnosis clarified after the observation period. The percentage of patients admitted to the hospital was 23%. There were 42 chest pain and 46 trauma patients. The impact of an observation ward on the service in ED was discussed.

Cardiovascular changes during morphine administration and spontaneous withdrawal in the rat

Morphine maintenance doses of 10 mg kg(-1) day(-1), 20 mg kg(-1) day(-1) and 30 mg kg(-1) day(-1) were administered to three groups of rats via miniosmotic pumps for 7 days to induce physical dependence. They were then allowed to undergo spontaneous withdrawal. Radiotelemetric blood pressure measurements showed that morphine increased systolic and diastolic blood pressure on the first day of morphine treatment and produced a dose dependent decrease in heart rate, systolic and diastolic blood pressure thereafter. After the peak depressive effect, development of tolerance to morphine was observed in systolic and diastolic blood pressure, but not in the heart rate. During spontaneous withdrawal, both systolic and diastolic blood pressure increased beyond pre-morphine levels for all doses and there was a rebound increase in heart rate at the 30 mg kg(-1) day(-1) dose. These results suggest that the improved sensitivity of telemetric measures combined with the use of minipumps for morphine treatment provide an animal model of spontaneous opioid withdrawal.

The matrix metalloproteinase matrilysin influences early-stage mammary tumorigenesis

Overexpression of the epithelial specific matrix metalloproteinase matrilysin (MAT) has been correlated with enhanced tumorigenicity and tumor cell invasion using in vitro model systems. We have determined the effects of MAT expression on the development of mammary tumorigenesis using transgenic mice that express human MAT under the control of the mouse mammary tumor virus (MMTV)-long terminal repeat promoter/enhancer. Examination of mammary glands from multiparous MMTV-MAT animals revealed the development of premalignant hyperplastic alveolar nodules in 50% of aged females. MMTV-MAT mice were mated with MMTV-neu transgenic mice to determine the effect of MAT on neu-induced mammary tumorigenesis. Bigenic MMTV-MAT/neu female offspring developed primary mammary tumors approximately 13 weeks earlier than did MMTV-neu controls. The mechanism of enhanced neu-induced tumorigenesis was explored. No discernible difference in Neu receptor dimerization or activation was detected in MMTV-MAT/neu tumors or mammary glands compared to MMTV-neu controls. A similar percentage of MMTV-MAT/neu and MMTV-neu tumors acquired deletions in the neu transgene, which have previously been shown to result in constitutive receptor activation. The presence of premalignant nodules and the accelerated development of oncogene-induced mammary tumors suggest that expression of MAT in the mammary epithelium contributes to early-stage mammary tumorigenesis.

Correspondence of electroglottographic closed quotient to vocal fold impact stress in excised canine larynges

The purpose of this study was to explore the possible use of the electroglottographic closed quotient (EGG CQ) as a noninvasive estimate of vocal fold impact stress (SI). Two excised canine larynges were used. Each larynx was mounted and vocal fold oscillation was induced using a humidified air source. Twenty-seven experimental trials were conducted for each larynx. Trials involved variations in vocal process gap, vocal fold elongation, and subglottic pressure. Simultaneous measures were made of vocal fold SI at the midpoint of the membranous vocal folds, and EGG CQ (dimensionless ratio). The results indicated that when threshold and saturation effects were excluded, the SI and the CQ were strongly related (linear correlation r = .83 and .96 for the two individual larynges, and .81 for the combined data). Within the region of linear relation, an increase of.15 in the CQ corresponded to about 1 kPa increase in SI for the combined data. Discussion focuses on possible clinical implications and the likely reasons for threshold and saturation phenomena.

Renin-aldosterone system can respond to furosemide in patients with hyperkalemic hyporeninism

Thirty-four patients (65.3+/-3.3 years of age, mean+/-SEM) with hyperkalemia (serum potassium >5.0 mEq/L) had measurement of their renin-aldosterone system. Nineteen patients (56%) had plasma renin activity (PRA) >1.5 ng/mL/h, which was not low, while 15 (44%) had PRA <1.5. Twelve of the 15 hyporeninemic hyperkalemic patients were studied to determine whether their renin-aldosterone system responded to 2 weeks of furosemide, 20 mg daily. Four were nonresponders: PRA averaged 0.3+/-0.1 ng/mL/h, and it did not increase with furosemide or respond to captopril before or after furosemide. Eight patients were responders: PRA averaged 0.6+/-0.2 ng/mL/h and increased with furosemide to 5.5+/-3.4 ng/mL/h. Captopril failed to increase PRA before furosemide, but PRA increased to 15.3+/-8.4 ng/mL/h after furosemide. Plasma aldosterone was low in both nonresponders and responders (3.5+/-1.2 ng/dL vs 5.8+/-2.5 ng/dL) and did not increase significantly with furosemide (4.3+/-1.7 ng/dL vs 8.7+/-2.5 ng/dL). Serum potassium did not fall and therefore did not limit the rise in aldosterone. Renin responders had greater body weight, were predominantly female (6/8 vs 2/4) and were more likely to have diabetes mellitus (7/8 vs 0/4). Plasma atrial natriuretic peptide (ANP) fell with furosemide in 8 of 8 responders and in 1 of the 2 nonresponders in whom it was measured. Neither group had suppressed plasma prorenin levels, indicating no suppression of renin gene expression. These results indicate that many hyperkalemic patients do not have suppressed PRA. Further, a majority of patients with suppressed PRA have high levels of ANP and can respond to diuretic therapy with a rise in PRA and a fall in ANP, suggesting physiologic suppression of the renin system by volume expansion. A minority of hyperkalemic patients with suppressed PRA had PRA that did not increase under these study conditions.

T lymphocytes with a normal ADA gene accumulate after transplantation of transduced autologous umbilical cord blood CD34+ cells in ADA-deficient SCID neonates

Adenosine deaminase-deficient severe combined immunodeficiency was the first disease investigated for gene therapy because of a postulated production or survival advantage for gene-corrected T lymphocytes, which may overcome inefficient gene transfer. Four years after three newborns with this disease were given infusions of transduced autologous umbilical cord blood CD34+ cells, the frequency of gene-containing T lymphocytes has risen to 1-10%, whereas the frequencies of other hematopoietic and lymphoid cells containing the gene remain at 0.01-0.1%. Cessation of polyethylene glycol-conjugated adenosine deaminase enzyme replacement in one subject led to a decline in immune function, despite the persistence of gene-containing T lymphocytes. Thus, despite the long-term engraftment of transduced stem cells and selective accumulation of gene-containing T lymphocytes, improved gene transfer and expression will be needed to attain a therapeutic effect.

An evaluation of the Behring Diagnostics Enzygnost Syphilis enzyme immunoassay

The Enzygnost Syphilis (Behring Diagnostics, Marburg, Germany) was evaluated (i) using sera already characterised using the rapid plasma reagin test and the Treponema pallidum hemagglutination test (TPHA); (ii) prospectively; (iii) using sera which are recognised as causing "problems" with enzyme immunoassays. The Enzygnost Syphilis was found to have a reproducibility of 98.6% and a sensitivity of 99.5% using sera known to be TPHA-reactive. When tested prospectively, the false reactive rate was 3.2%. These results show that the assay performs sufficiently satisfactorily for its introduction as a screening assay for evidence of syphilis infection in our population.

Evaluation of plasma osmolality and hormone responses in elderly chronic hemodialysis patients with excessive interdialytic weight gain

Elderly patients may exhibit changes in plasma hormone levels, as well as thirst disorders. Two groups of elderly hemodialysis patients were evaluated to determine if excessive interdialytic weight gain was related to differences in postdialysis plasma osmolality or postdialysis measurement of plasma renin activity, or plasma levels of angiotensin II (a dipsogenic hormone), aldosterone, and vasopressin. Patients mean age was 77.0 +/- 8.8 years and patients were divided into groups, I and II, with less than or greater than 2 kg interdialytic weight gain. Postdialysis plasma osmolality was similar in both groups of patients (309.3 +/- 2.3 vs. 309.6 +/- 2.4 mOsm/Kg, p = 0.8) and postdialysis AVP levels also were no different (2.7 +/- 0.6 vs. 2.1 +/- 0.2 pg/mL, p = 0.3). There was also no statistical difference between postdialysis angiotensin II and aldosterone levels in either group of patients. Plasma renin activity (PRA) was also not different in either group (2.3 +/- 1.1 vs. 0.43 +/- 0.1 ng/mL/hr, p = 0.1), but group I patients, with less than 2 kg weight gain, tended to exhibit higher PRA values perhaps reflecting proximity to their dry weight postdialysis. Since excessive fluid intake did not appear to relate to plasma osmolality and hormone levels studied, it might be suggested that excessive drinking could be due to excessive sodium intake associated with personal dietary habits or perhaps other as yet unmeasured factors.

Probable human infection with a newly described virus in the family Paramyxoviridae. The NSW Expert Group

After an apparently new virus in the family Paramyxoviridae was isolated from pigs in August 1997, an investigation was carried out to assess its risk for humans. More than 250 persons with potential exposure to infected pigs were tested serologically. Two piggery workers with intense occupational exposure had high convalescent-phase antibody titers to this new virus. In early June 1997, both workers had an influenzalike illness with rash; serologic testing showed no alternative cause. Strong evidence indicates that the two men became ill from this new virus, but the mode of transmission from pigs to humans remains unknown.

Human papillomavirus and host variables as predictors of clinical course in patients with juvenile-onset recurrent respiratory papillomatosis

This study provides the first systematic evaluation of papillomavirus type and viral mutation occurring during the course of juvenile-onset recurrent respiratory papillomatosis. One hundred ninety-nine consecutive papillomas excised from 47 children between 1981 and 1996 at The New Children's Hospital in Sydney, Australia, were tested for human papillomavirus (HPV) DNA by PCR. PCR products from the viral upstream regulatory region (URR) enhancer were sequenced, and variation was related to clinical variables. Forty-four of the 47 children had HPV-induced papillomas, with type 11 accounting for 24 (55%) and type 6 accounting for 19 (43%); one (2%) was positive for either type 6 or 11. Overall, 183 (98%) of the 186 samples with amplifiable DNA were HPV positive. There was no change in HPV type over time and no statistically significant association between HPV type and disease aggressiveness. One novel, large-scale URR duplication was identified in an HPV type 11 isolate in the last of a series of six papillomas examined and the first from the bronchus. However, the duplication was not found in HPV type 11 isolates from the associated pulmonary carcinoma and its metastases in other organs. Three of 14 URR point mutations coincided with transcription factor binding sites, but there were no obvious associations with clinical course. Chi-square and multiple linear regression analyses of clinicopathological variables revealed early age at diagnosis (less than 4 years) as an independent predictor of aggressive disease (P < 0.001). A bimodal distribution of the age at diagnosis was noted, with peaks at 2 and 11 years of age.

Assessment of an instrument for automated reagent and specimen dispensing in blood banking

We have evaluated a semi-automated computer controlled dispensing device in conjunction with microtube technology for the performance of routine blood grouping and antibody screening procedures. A total of 787 specimens have been tested, 78 with unexpected antibodies previously identified by manual microtube methods. All were tested in duplicate in different order; there was complete agreement in blood group (ABO, RhD) determinations and the unexpected antibodies were found in the appropriate microtube location in all duplicate sets of results. We conclude that the device accurately and reproducibly dispenses cells, sera and reagents. The savings of technologists' time over traditional manual tube methods exceed 75%, excluding the time to perform elements common to both methods. The combination of automation and microtube technology offers the opportunity for substantial savings in technologist time with accuracy in reagent and specimen dispensing.

The influence of restraint on blood pressure in the rat

We examined the influence of procedures used in blood pressure measurement on blood pressure and the effects of antihypertensive agents. Subjects were spontaneously hypertensive rats (SHR) and their Wistar/Kyoto (WKY) controls. Blood pressure was recorded by telemetry. Twenty-four h baseline pressure were measured, and the effect of minor handling on blood pressure and heart rate was examined. The influence of restraint such as is used for tail-cuff blood pressures was examined. The effects of three different antihypertensive drugs was also examined in the SHR. In the home-cage environment, the SHRs showed higher systolic blood pressures, but had similar hypertensive responses to minor handling as the WKYs. Both strains had elevated heart rate and blood pressure when restrained in the manner used for tail-cuff readings. The antihypertensive effects of captopril and losartan in the SHR were unchanged when the animals were restrained but the hypotensive effect of hydralazine was greater. These results confirm that significant changes in heart rate and blood pressure can occur as a result of the minor procedures frequently used in blood pressure recording in both SHR and WKY rats. This suggests that telemetry may have significant advantages as a method for continuous blood pressure monitoring. The pharmacological profile of antihypertensive drugs may well be different in animals where telemetry is employed and are not subject to the stresses involved in previous methods of monitoring blood pressure.

Sexually-transmitted diseases in Singapore--trends in the last two decades

We review the epidemiology and trends of sexually transmitted diseases (STDs) in Singapore from 1977 to 1996. There has been a progressive decline in the incidence of bacterial STDs over the period of observation. However, viral STDs have not shown the same trends, remaining at a relatively constant level. Early detection and treatment of STDs, and health education and prevention measures targeting sex workers have been a major factor in controlling STDs. Vigilant monitoring of antibiotic resistance patterns in Neisseria gonorrhoeae has allowed timely changes to recommended treatment regimens. The advent of the human immunodeficiency virus (HIV) infection pandemic in the 1980s and public education campaigns have contributed to the success of the STDs control programme. In view of the incurable nature of many viral STDs, prevention and counselling have become a cornerstone of STD control. Surveillance and monitoring of STD trends will continue to provide important information regarding the effectiveness of existing health programmes and help us formulate new plans for the future.

A knowledge, attitudes, beliefs and practices (KABP) survey on HIV infection and AIDS among doctors and dental surgeons in Singapore

An anonymous postal questionnaire survey studying the knowledge, attitudes, beliefs and practices on human immunodeficiency virus (HIV) infection was conducted among all registered medical and dental practitioners in Singapore in 1996. In all, 1523 replies were received, yielding a response rate of 29.3%. The level of knowledge regarding transmission and prevention was generally good, although there were a number who believed that HIV could be transmitted by the respiratory and oral routes. However, knowledge regarding diagnosis and medical management was unsatisfactory. Although a large majority felt they had the ethical obligation to treat HIV patients, only half of them indicated their willingness to do so if they were given the choice. The majority (62.3%) supported the idea of routine preoperative HIV testing for patients, but fewer (40%) supported mandatory HIV testing for health care workers. Dentists seemed more sensitive to issues involving transmission in the workplace, and 95% of them practised universal precautions. Continuing medical education on HIV infection is required to improve and maintain the level of knowledge and competency of doctors and dentists in Singapore.

Concentrations of adenosine and its metabolites in the rat retina/choroid during reperfusion after ischemia

PURPOSE

Little is known about the nature of biochemical disturbances during reperfusion after retinal ischemia. Previous studies have suggested that adenosine is responsible for regulation of retinal blood flow soon after ischemia has ended. Therefore, in this study we measured concentrations of adenosine and its metabolites in the rat retina/choroid after brief (10 min) or prolonged (60 min) periods of ischemia, and the functional consequences of inhibiting adenosine metabolism.

METHODS

Ischemia was produced in anesthetized rats by ligation of the central retinal artery. The eyes were frozen in situ and purine nucleoside concentration was determined by high performance liquid chromatography. The functional effects of pre-ischemic inhibition of xanthine dehydrogenase/xanthine oxidase were assessed by measurement of the electroretinogram before, during, and up to 7 days following 60 min ischemia.

RESULTS

Changes in the concentrations of adenosine and its metabolites were significant early in the reperfusion period, and were greater in magnitude and occurred earlier in prolonged, compared to brief, ischemic periods. Concentrations of adenosine, inosine, and hypoxanthine remained elevated for 30 min following the end of 60 min ischemia, and xanthine concentration was significantly elevated until 60 min after the end of either 10 or 60 min of ischemia. The onset of its peak value after ischemia was delayed in comparison to that of adenosine. Ischemia-evoked increases in xanthine concentration were attenuated by inhibition of adenosine deaminase or xanthine oxidase/xanthine dehydrogenase. Pre-ischemic inhibition of xanthine oxidase/xanthine dehydrogenase by oxypurinol (40 or 80 mg/kg intraperitoneally [IP]) resulted in a significant improvement in recovery of the a and b waves of the electroretinogram in comparison to a saline-treated control group.

CONCLUSIONS

These results indicate that adenosine is a major component of the biochemical changes that occur after retinal ischemia. Long-lasting increases in xanthine concentration during reperfusion after ischemia could be a source of oxygen free radicals that may contribute to delayed injury of the retina, attempts to decrease xanthine concentration would ideally be initiated within one hour after the end of ischemia.

Endocrine modulation of the neurotoxicity of gp120: implications for AIDS-related dementia complex

HIV infection often involves the development of AIDS-related dementia complex, a variety of neurologic, neuropsychologic, and neuropathologic impairments. A possible contributor to AIDS-related dementia complex is the HIV envelope glycoprotein gp120, which damages neurons via a complex glutamate receptor- and calcium-dependent cascade. We demonstrate an endocrine modulation of the deleterious effects of gp120 in primary hippocampal and cortical cultures. Specifically, we observe that gp120-induced calcium mobilization and neurotoxicity are exacerbated by glucocorticoids, the adrenal steroids secreted during stress. Importantly, this deleterious synergy can occur between gp120 and synthetic glucocorticoids (such as prednisone or dexamethasone) that are used clinically in high concentrations to treat severe cases of the Pneumocystis carinii pneumonia typical of HIV infection. Conversely, we also observe that estradiol protects neurons from the deleterious actions of gp120, reducing toxicity and calcium mobilization.

STD/AIDS knowledge and risk behaviour among masseuses and bar hostesses in Singapore

Sex workers are not confined to brothels, they also include a variety of individuals who practise part-time in establishments conductive to sexual liaisons. We undertook to study the extent of sex work among masseuses and nightclub hostesses and the level of AIDS and STD knowledge in these 2 groups. The studies were conducted in 1993 and 1996. Altogether 1244 masseuses and 746 hostesses attended educational sessions at the STD clinic, during which they were also surveyed for knowledge on AIDS and STDs, and practices which may put them at risk of infection; they were also offered tests for HIV and syphilis. Knowledge on AIDS transmission was good, knowledge of other aspects of AIDS and STDs was not. Sexual activities resulting from the conduct of their work was practised by only a minority of masseuses (13.5%) and hostesses (7.9%). Among those who engaged in sexual activities at work, masseuses practised safe sex more commonly than hostesses (83.5% vs 27.6%). The prevalence of HIV (0.175% in hostesses, 0% in masseuses) and syphilis (0.87% in hostesses and 1.7% in masseuses) was very low in both groups.