The small hospital's role in poliomyelitis

Medical skills should be developed by the staffs of smaller hospitals for the differential study of patients with symptoms resembling those of poliomyelitis in order to provide the rudiments of care for the occasional patient with mild poliomyelitis, to recognize the indications which point to the necessity of superior technical assistance, and to decide when it is appropriate to move patients to better equipped centers. The impetuous acquisition of mechanical aids for the treatment of special problems will be effective in small communities only to the extent that this equipment is kept serviceable and is operated by persons of sufficient skill. Epidemic situations in a small community can be met only by mobilization of facilities under adequate direction and by integration of care with that provided by larger treatment centers.     

Hydrolysis of dilute acid pretreated mixed hardwood and purified microcrystalline cellulose by cell-free broth from Clostridium thermocellum

The cellulase activity in cell-free broths from the thermophilic, ethanol-producing anaerobic bacterium Clostridium thermocellum is examined on both dilute-acid-pretreated mixed hardwood (90% maple, 10% birch) and Avicel. Experiments were conducted in vitro in order to distinguish properties of the cellulase from properties of the organism and to evaluate the effectiveness of C. thermocellum cellulase in the hydrolysis of a naturally occurring, lignin-containing substrate. The results obtained establish that essentially quantitative hydrolysis of cellulose from pretreated mixed hardwood is possible using this enzyme system. Pretreatment with 1% H(2)SO(4) and a 9-s residence time at 220, 210, 200, and 180 degrees C allowed yields after enzymatic hydrolysis (percentage of glucan solubilized/ glucan potentially solubilized) of 97.8, 86.1, 82.0, and 34.6%, respectively. Enzymatic hydrolysis of mixed hardwood with no pretreatment resulted in a yield of 10.1%. Hydrolysis yields of >95% were obtained from approximately 0.6 g/L mixed hardwood pretreated at 220 degrees C in 7 h at broth strengths of 60 and 80% (v/v) and in approximately 48 h with 33% broth. Hydrolysis of pretreated mixed hardwood is compared to hydrolysis of Avicel, a pure microcrystalline cellulose studied previously. The initial rate of Avicel hydrolysis saturates with respect to enzyme, whereas the initial rate of hydrolysis of pretreated wood is proportional to the amount of enzyme present. Initial hydrolysis rates for pretreated wood and Avicel at 0.6 g/L are greater for wood at low broth dilutions (1.25: 1 to 5 :1) by up to 2.7-fold and greater for Avicel at high broth dilutions (5 : 1 to 50 : 1) by up to 4.3-fold. Maximum rates of hydrolysis are achieved at <2 g substrate/L for both pretreated wood and Avicel. The substrate concentration at one-half the maximum observed rate for C. thermocellum broths is smaller for pretreated mixed hardwood than for Avicel and decreases with increasing broth dilution for both substrates. An initial activity per volume broth of approximately 11 mumol soluble glucose equivalent produced/L broth/min is observed for mixed hardwood pretreated at 220 degrees C and for Avicel at high broth dilutions; the initial activity per volume broth for Avicel is lower at low broth dilutions. The results indicate that pretreated wood is hydrolyzed at rates comparable to Avicel under many conditions and at rates significantly faster than Avicel under several conditions.     

The growth of Saccharomyces cerevisiae CBS 426 on mixtures of glucose and succinic acid: A model

Saccharomyces cerevisiae CBS 426 was grown in continuous culture in a defined medium with a mixture of glucose and succinic acid as the carbon source. Growth on succinic acid was possible after long adaptation periods. The flows of glucose, succinic acid, oxygen, carbon dioxide, and biomass to and from the system were measured. It proved necessary to expand our previous model to accommodate the active transport of succinic acid by the cell. The values found for the efficiency of the oxidative phosphorylation (P/O) and the amount of ATP needed for production of biomass from monomers gave the same values as found for substrate mixtures taken up passively.     

A comparative study of the enzymatic hydrolysis of acid-pretreated white pine and mixed hardwood

Removal of hemicellulose by acid pretreatment in a flow reactor followed by enzymatic hydrolysis of the neutralized slurry has resulted in glucose yields as high as 95% for mixed hardwood. For white pine, however, the maximum glucose yield is 65%. Although pine has a higher extractives content, removal of the extractives prior to enzymatic hydrolysis does not increases the glucose yield. Pore size measurements reveal that the increase in pore volume, in the size range of the cellulase molecule, following pretreatment for pine is only about one-half the value obtained with mixed hardwood. This suggests that pore volume is an important determinant of substrate-enzyme reactivity.