Precision stabilization of the optical frequency in a large ring laser gyroscope.

Pressure-induced fractional changes of 10(-7) in the geometry of a large He-Ne ring laser gyroscope induce backscatter phase changes and thus a fractional pulling of the Sagnac frequency of ~5 x 10(-3). To counter this, the optical frequency was stabilized against an iodine-stabilized laser with a high-finesse Fabry-Perot interferometer and piezoelectric control of the ring perimeter. This scheme, although limited in principle by residual geometric asymmetry and in practice by low beam powers (10 pW), stabilized the perimeter to 2.4 nm (6 x 10(-10) or 300 kHz for the optical frequency) and the Sagnac frequency to 100 parts per million over several days.

Current treatment of allergic rhinitis and sinusitis.

Sinusitis is an infectious, inflammatory disease. Aggressive, multifaceted treatment is often required for control, with emphasis on anti-inflammatory therapy. Medical and surgical treatment is similar in children and adults, but more aggressive therapy, particularly surgery, is more controversial in the former.

Interactive multimedia dental education: the next five years and beyond.

This presentation is intended to provide "Ten Good Reasons" why interactive multimedia should play a major role in both undergraduate curriculum and graduate level continuing education in the next five years. Multimedia is currently best presented on CD-ROM disks, but virtual reality, interactive television, video-desktop conferencing, and Internet applications will become available before the end of the century. Many dental schools, associations and private companies have already entered the development and production of dental multimedia titles, and it is anticipated that schools and dentists will soon be constrained to purchase multimedia capable systems to take advantage of the "Ten Good Reasons." Guidelines are given to those who desire to publish material in interactive multimedia format. A vision of the future is presented.

In vitro activities of cefoperazone and sulbactam singly and in combination against cefoperazone-resistant members of the family Enterobacteriaceae and nonfermenters.

Among 28,000 isolates of the family Enterobacteriaceae and nonfermenters isolated at multiple medical centers, 1,084 (4%) were resistant to cefoperazone (MIC, greater than or equal to 64 micrograms/ml) and 1,711 (6%) exhibited cefoperazone MICs of 2 to 32 micrograms/ml. Ninety-six percent of these 2,795 isolates produced beta-lactamase, as determined by the nitrocefin test. Sulbactam alone (8 micrograms/ml) was inactive against 99.6% of the isolates other than Acinetobacter calcoaceticus and Pseudomonas cepacia. Sulbactam enhanced the activity of cefoperazone against 56% of the isolates of the family Enterobacteriaceae and 44% of the nonfermenters. In the presence of sulbactam concentrations of less than or equal to 8 micrograms/ml, 65% of the cefoperazone-resistant isolates had reductions in cefoperazone MICs of greater than or equal to 2 log2 dilution steps and were susceptible to less than or equal to 32 micrograms/ml. Antagonism was not observed.

Serum IgE and human immunodeficiency virus (HIV) infection.

Human immunodeficiency virus infection is characterized by a progressive depletion of helper T-lymphocytes and, like allergic diseases, is associated with altered T cell regulation. Total serum IgE was measured in 67 infected male subjects, 27 uninfected heterosexual male subjects, and 18 uninfected homosexual male subjects. The mean IgE level (132 IU/ml) of infected subjects with a helper T-lymphocyte number less than or equal to 200/mm3 was significantly greater than mean IgE levels of the uninfected heterosexual (38 IU/ml) and homosexual (35 IU/ml) groups. IgE levels were inversely related to both helper T cell and suppressor/cytotoxic T cell numbers but not to IgG or IgA levels. The increase in IgE was not a reflection of an increased prevalence of atopic disease (allergic asthma, allergic rhinitis, or atopic dermatitis) in the infected subjects. The elevation of IgE may be related to a difference among the groups in T cell production of IgE regulatory lymphokines.

Local reactions to stinging insects (Hymenoptera).

Hymenoptera stings cause cutaneous nonallergic local reactions of limited size and duration in most individuals. Some subjects experience an allergic local reaction (large local reaction) to a sting that is greater than 10 cm in diameter and may last for up to 5 days. The nonallergic local reaction is a toxic response to venom constituents, while the large local reaction appears to be caused by an allergic reaction to venom proteins. The IgE-mediated late-phase reaction is probably responsible for most of these reactions; however, a cell-mediated mechanism, or a combination of the two, is possible. A diagnostic workup is not recommended for local reactions. However, skin testing with Hymenoptera venoms (bee, wasp, hornet, and yellowjacket) identifies most subjects with sting-induced large local reactions. Therapy of the local reactions is symptomatic. An oral glucocorticosteroid, H1 antagonist and possibly a H2 antagonist are indicated for treatment of large local reactions. Venom immunotherapy is effective in preventing recurrences of large local reactions in children but is not usually recommended for either adults or children.

Evaluation of four newer antimicrobial agents in the Avantage susceptibility test system.

Antimicrobial elution disks containing amoxicillin-clavulanic acid (Augmentin), cefotetan, ciprofloxacin, or norfloxacin were tested in the Avantage automated susceptibility test system. Performance was compared against an agar diffusion procedure in a three-site collaborative study. Results of 1,500 comparison with amoxicillin-clavulanic acid showed a full accord (agreement of both systems) of 93.6% and an essential accord (agreement excluding minor discrepancies) of 97.6%. Results for cefotetan showed a full accord of 95.1% and an essential accord of 98.3% by the two methods. Results for both ciprofloxacin and norfloxacin were in full accord for more than 98% of tests with gram-negative bacilli and staphylococci, but tests with enterococci gave 38 and 26.1% minor discrepancies (the result of one method was resistant or susceptible and the result of the other method was intermediate), respectively. The results indicated that the Avantage test system is accurate and reliable and provides appropriate determination of bacterial susceptibility with the four antibiotics tested.

Comparative in vitro activity of lomefloxacin (SC 47111 or NY-198) against fresh clinical bacterial isolates.

The in vitro antibacterial activity of a new difluorinated quinolone (lomefloxacin) was compared with that of ten selected antibiotics against 744 fresh bacterial isolates representing 32 species. Lomefloxacin was comparable to other quinolones tested against Enterobacteriaceae (MIC90, less than or equal to 0.25 micrograms/ml) and generally more effective than other compounds tested against Staphylococcus spp. and Pseudomonas aeruginosa with MIC90s of less than or equal to 2 and less than or equal to 4 micrograms/ml, respectively.

In vitro inactivation of aminoglycosides by cephalosporin antibiotics.

The in vitro inactivation of aminoglycoside antibiotics by semisynthetic penicillins complicates antibiotic assays. Due to the increasing number of new cephalosporins and use of aminoglycoside-cephalosporin combinations, we determined the in vitro stability of 28 aminoglycoside-cephalosporin combinations (gentamicin sulfate, tobramycin sulfate, netilmicin sulfate [10 micrograms/mL], and amikacin [20 micrograms/mL] in combination with cefazolin sodium, cefoxitin sodium, cefoperazone sodium, cefotaxime sodium, ceftazidime acid pentahydrate, cefsulodin sodium, or cefpiramide sodium at 100, 200, and 300 micrograms/mL). These mixtures were incubated at 37 degrees C and sampled at 0, 8, and 24 hours. Amikacin and tobramycin were most stable and netilmicin was the least stable of the aminoglycosides. Cefoxitin, ceftazidime, and cefotaxime were the least inactivating of the cephalosporins. When combined with first- and second-generation cephalosporins, aminoglycosides are relatively stable, but some laboratory precautions may be necessary when determining aminoglycoside levels in the presence of third-generation cephalosporin compounds.

In vitro activity in deptomycin (LY-146032) compared with other antimicrobial agents against gram-positive cocci.

A comparison was made of the activity of deptomycin (LY-146032) with that of ampicillin, cephalexin, cefamandole, cephalothin, erythromycin, teicoplanin, tetracycline, and vancomycin. The minimal inhibitory concentration (MICs) for greater than or equal to 90% of 356 Gram-positive cocci, against deptomycin, were less than or equal to 2 micrograms/ml. The MICs for the other antimicrobials varied greatly depending on the compound. A slight and unexplained inoculum effect was observed for LY-146032.

Use of the Bac-T-Screen to predict bacteriuria from urine specimens held at room temperature.

Results from the Bac-T-Screen (BTS) of fresh urine specimens were compared with the BTS results obtained when the same urine specimens had been held at room temperature for 24 h. Of the 246 specimens studied, 43 were initially BTS positive, 11 were false-negative, and 39 had greater than or equal to 10(5) CFU/ml. After 24 h at room temperature an additional 60 specimens had greater than or equal to 10(5) CFU/ml, of which only 16 were BTS positive; 10 specimens still gave false-negative results, and the number of false-positive specimens increased by only 6.5% of all specimens. For significant specimens (containing greater than or equal to 10(5) CFU of probable pathogens per ml), the predictive value of a negative test changed by only 0.1% (99.5 to 99.4%), whereas the sensitivity of the test remained at 96.4% for incubated specimens. Of those specimens that developed greater than or equal to 10(5) CFU/ml in vitro, 85% contained gram-negative bacilli. Neither bacteria grown in vitro nor urine specimens from normal females containing greater than or equal to 10(5) CFU/ml were positive with the BTS. For reasons not entirely understood, the BTS system may be unique in its ability to discriminate between bacteria which represent true bacteriuria and those which are present because of contamination, possibly due to other cellular elements present in infection-related bacteriuria, namely leukocytes and sloughed bladder epithelial cells.

Comparison of visual and photometric Bac-T-Screen results.

The Bac-T-Screen (Marion Laboratories, Kansas City, MO) was used to screen 826 urine specimens. Of these, 85 either pigmented or clogged the Bac-T-Screen filter and could not be evaluated. Results for the remaining 741 specimens were examined both visually and photometrically by a newly developed photometric card reader. The results were then compared. Screening results for all urines containing greater than or equal to 10(5) pathogens/mL were equivalent for both methods, with sensitivity and predictive negative values of greater than 98% and greater than 99%, respectively. The predictive values of positive tests were also equivalent at 57.5% for visual and 59.6% by photometry. The overall agreement varied with the card reader value used because the photometric card-reader procedure allows the user to select desired sensitivity and specificity levels.

In vitro inactivation of aminoglycosides by apalcillin.

Apalcillin, at concentrations of 75, 150, 300, and 600 micrograms/ml, was combined in vitro with amikacin, gentamicin, netilmicin, or tobramycin. Incubation at 37 degrees C resulted in an apalcillin concentration-dependent and time-dependent decrease of aminoglycoside activity of up to 60%. Amikacin was the most stable and tobramycin was the least stable aminoglycoside under the conditions tested.

Research in pediatric diarrhea.

PIP: It is obvious from this conference that although there are many more unresolved problems and questions than answers, the definition of the problems associated with pediatric diarrhea which face the medical/scientific community has been painstakingly, persistently, and frequently brilliantly illuminated by the efforts of many investigators. The presentations in this session will address and define areas for future productive investigation, particularly as they relate to the specific challenges of early feeding, nutrition, immunobiology, and the application of present knowledge to underdeveloped areas of the world. The lack of effectiveness of the many vaccines available for prophylaxis against gastrointestinal infection illustrates the need for fundamental research into the immunobiology of the intestine. It is apparent that humoral immunoglobulin cannot adequately forecast resistance to enteric challenge. Yet, while the newly appreciated role of surface IgA as a protector of intestinal surfaces against enteric invasion significantly updates understanding of intestinal immunology, it fails to adequately explain observations on the behavior and function of either the cellular elements of the intestinal immune mechanism or the function of other immunoglobulins present in the intestine. Dr. Harry R. Hill will discuss immunologic factors associated with the gastrointestinal tract. Dr. Jose Santos will present an update on one of the more complex issues associated with pediatric diarrhea to arise during the last decade, i.e., the influence of nutrition and the various states of malnutrition on the severity and outcome of diarrheal disease. Dr. Richard Guerrant will review the most serious problems in diarrheal control and research to be faced in the next decade. Areas of concern include the impact of polymicrobial diarrheal disease on morbidity, chronic vs. acute diarrhea, new etiologies of diarrheal disease, and the intraepidemic epidemiology of etiologic agents. Dr. John M. Masten will conclude the conference with a synopsis of the presentations.^ieng

Effect of urine preservation on urine screening and organism identification.

Three urine preservation-transport methods were examined for their effect on rapid urine-screening procedures. Results from fresh urine specimens, screened for bacteriuria by leukocyte esterase, nitrate, Autobac, Bac-T-Screen, Auto Microbic System (AMS), and bioluminescence procedures, were compared with urine-screen results from urine specimens held for 24 hours at room temperature in chemical preservatives. Quantitative discrepancies ranged from 0%, for urine preserved with glycerin-boric acid-sodium formate and tested by AMS or leukocyte esterase, to 21% for urines in the same preservative tested by bioluminescence or nitrate. Up to 62% of the organism identifications made from preserved urine specimens tested by the AMS urine card were in error. These data suggest that it may be inadvisable to use weak organic acid-based urine preservation systems in conjunction with these urine-screen procedures.

Gram stain in Legionnaires' disease.

A case of Legionnaires' disease is presented in which gram staining of impression smears from lung biopsy specimens showed Legionella pneumophila while other laboratory findings remained negative. This case illustrates the usefulness of gram staining in this disease and in the management of therapy.

Mycobacterium thermoresistibile infection in an immunocompromised host.

This is the second report of Mycobacterium thermoresistibile as the etiological agent of a pulmonary granuloma and the first occurrence of this organism in a patient who has not been outside the continental United States. The organism is susceptible to rifampin, ethambutol, and streptomycin but resistant to isoniazid and p-aminosalicylic acid.

In vitro susceptibility of Nocardia asteroides to 25 antimicrobial agents.

Fifty-two clinical isolates of Nocardia asteroides were tested by agar dilution for their susceptibility to 25 antimicrobial agents. In general, susceptibility could not be predicted based on the antibiotic class tested. However, the beta-lactams, including third-generation cephalosporins, were generally ineffective (MIC for 90% of the organisms [MIC90], between 64 and greater than 256 micrograms/ml), whereas minocycline and doxycycline were generally effective (MIC90, 4 and 8 micrograms/ml, respectively). Cycloserine was not effective below 60 micrograms/ml. The MIC50 and MIC90 of sulfamethoxazole was 16 and 32 micrograms/ml, respectively, and that of trimethoprim varied widely (16 and greater than 256 micrograms/ml, respectively). Based on MIC90 data, only doxycycline, minocycline, sulfamethoxazole, and imipenem could be applied empirically.