Feasible improvements in vaccines in the Expanded Programme on Immunization.

Feasible improvements in existing vaccines of the Expanded Programme on Immunization are reviewed. The toxicity of pertussis vaccines can probably be reduced and the immunogenicity increased by recently instituted improvements in purity and selectivity. Candidate vaccines containing inactivated pertussis toxin, with or without other components, are in use in Japan and in controlled trials elsewhere. Inactivated poliovirus vaccines have been improved over the past decade and presently show promise of inducing immunity with as few as two doses administered in infancy. At the same time, improved methods for delivering the oral poliovirus vaccine through mass vaccination campaigns are being increasingly employed throughout the developing world. Major improvements in the measles vaccine will probably come from the development of new stabilizers and the use of vaccines that are immunogenic in the presence of maternal antibody.

PIP: The toxicity of pertussis vaccines can probably be reduced and the immunogenicity increased by recent improvements in purity and selectivity. Inactivated poliovirus vaccines show promise of inducing immunity with 2 doses administered in infancy. The Expanded Program on Immunization (EPI) uses the diphtheria-tetanus-pertussis (DTP) vaccine, poliovirus vaccine, and measles virus vaccine. The incidence of serious toxicity (particularly screaming fits, attacks of pallor, or unusual behavior) and encephalitis is very low. A superior partially purified pertussis vaccine was developed by Sato that contained both the pertussis toxin and filamentous hemagglutinin. With the toxicity of purified-component vaccines reduced, the relevant pertussis antigens can be increased to the point where 2 doses will suffice. The present live oral polioviruses vaccine (OPV) and inactivated poliovirus vaccine (IPV) are prone to thermal instability and a cold chain may be a necessary component of immunization with live poliovirus vaccine in the near future. It was shown that 4th and 5th doses of OPV given at 4-week intervals after the 3rd dose elevated the proportion of infants who developed serum antibody to types 1, 2, and 3 antigen from 69%, 90%, and 76%, respectively, up to 83%, 96%, and 82%. DTP vaccine improved to 2 doses is adequate for initial coverage then full immunization for DPT, poliomyelitis, and measles at 3 and 9 months of age. Vero cells of a heteroploid karyotype and of an indefinite lifespan were used to develop a poliovirus vaccine, as they do not produce tumors in rodents. WHO and the US Food and Drug Administration accepted them as safe as cell substrates for certain purified viral vaccines. Measles virus vaccines also have thermal instability and immunogenicity. Thermal instability was greatly reduced with the introduction of buffered glycerol-sorbitol before lyophilization. Immunogenicity in the presence of maternally derived antibody while indicating successful immunization also indicates susceptibility to measles. In a trial of aerosolized vaccine in Mexican children of different ages using the Edmonston-Zagreb (E-Z) vaccine and the Edmonston-Swartz (E-S) vaccine, successful immunization was high even in 6-month-old infants with the E-Z strain but not with the E-S strain. Both OPV and IPV will continue in general use and improvements will come from more efficient delivery schemes, particularly pulse immunization.

Adhesives in orthopaedic surgery. A review of the literature and in vitro bonding strengths of bone-bonding agents.

Adhesives may offer a number of advantages over conventional metal osteosynthesis in the treatment of fractures: ease and speed of fixation are improved, they have the anatomy to anatomically coapt small fragments, and hardware removal is not necessary. A review of the literature was performed to evaluate experiments with collagen and other biologic adhesives, epoxy resins, polyurethane foam, cyanoacrylates, zinc polycarboxylate, polymethylmethacrylates, and fibrin adhesives pertaining to osteosynthesis. Cyanoacrylates, polymethylmethacrylates, and fibrin adhesives are currently being investigated. These agents are tested to evaluate their bone-bonding strength. Cyanoacrylates of biologically tolerated chain length did not develop useful bonding in cancellous bone; they bond well to cortical bone only with meticulous surface preparation. Fibrin adhesives developed only minimally useful bonding. Polymethylmethacrylate developed surgically useful bonding in osteosynthesis where conventional fixation is impossible.

Evaluation of the efficacy of Alka-Seltzer Effervescent in gastric acid neutralization.

A commercially available antacid, a mixture of sodium and potassium bicarbonates and citric acid (Alka-Seltzer Effervescent), was evaluated experimentally and clinically for its efficacy in neutralizing 0.1 N HCl and gastric contents. In an in vitro titration study, Alka-Seltzer Effervescent buffered 5-30 times the volume of HCl with a pH between 1.0 and 2.0 to above a pH of 2.5. In an isolated canine pulmonary lobe model, aspiration of the antacid or acid-antacid mixture caused only a mild increase in lobe weight and did not increase intrapulmonary shunting. In the clinical study, when the antacid was given 5-40 min before administration of general anesthesia in a group of patients for emergency surgery, the pH of the gastric contents in each patient was increased to above 4.0. This contrasts with the control group of patients, which showed 50% (P less than 0.05) of the patients were at risk when no antacid was administered. Preoperative administration of Alka-Seltzer effectively increases the pH of the gastric contents in patients undergoing emergency surgery.

Fluress, fluorescein and benoxinate: recovery from bacterial contamination.

The ability to recover from bacterial contaminations with Staphylococcus auresus and Pseudomonas aeruginosa was determined for three optometric DPAs: Fluress, fluorescein and benoxinate. Results show that Fluress recovers from contamination more rapidly than benoxinate or fluorescein. This ability to recover from contamination and the relative ease of use of Fluress may make it the DPA choice for a number of optometric procedures including applanation tonometry.