Unsteady-state operation of continuous fermentor for enhancement of cell mass production

The transient behavior of continuous fermentation is studied concentrating on the time scale intrinsic to the system. The time scale is the time required for the fermentorto reach a stable steady state after the disturbance of cell mass is introduced. When the cell concentration is disturbed from the steady-state value, in particular, at the dilution rate near washout, the transient period becomes extended significantly, and the steady state is resumed sluggishly. This sluggish transient behavior could be turned to an advantage for enhancing the cell mass output rate. The proposed transient operation is a continuous fermentation whereby a positive disturbance in the cell mass is introduced, so that the cell concentration is higher than the steady-state value for an extended transient period. It is shown that a significantly higher cell mass production than that from the steady-state continuous fermentation can be achieved. Simple experiments were performed to demonstrate the improvement of cell (Candida utilis) productivity.     

Light-adaptation in the photophobic response by Stentor coeruleus

Effects of preillumination on photophobic response (light-adaptation) and recovery of the photophobic sensitivity in the dark (dark-adaptation) in Stentor coeruleus were examined. When the cells were preilluminated with white light of 7.80 W/m² for 2 min, the fluence-rate response curve of photophobic response was shifted toward higher light intensities by half an order of magnitude compared to the one without preillumination. Preillumination with a higher light intensity resulted in a further shift of the fluencerate response curve. An action spectrum for light-adaptation showed a primary peak at 610 nm and secondary peaks at 540 and 480 nm which are almost identical to the peaks observed in the photophobic action spectrum.The light-adapted cells showed a recovery of their photophobic sensing ability following dark treatment. Dark-adaptation resulted in total recovery of photophobic sensing ability in 8 minutes for the most cases examined.     

The different effects of recombinant human tumor necrosis factor on rat fibrosarcoma sublines

Summary The antitumor effect of recombinant human tumor necrosis factor (rH-TNF) on two clones of rat fibrosarcoma with different metastatic potential to lymph nodes was examined. The colony formation of clone A, which has high metastatic potential, was completely inhibited by continuous exposure to rH-TNF at 50 U/ml. In contrast, colony formation of clone G, which has low metastatic potential, was not inhibited by high concentrations of rH-TNF (10,000 U/ml). The inhibitory effect of rH-TNF on colony formation by clone A was also observed with a 1-h exposure to rH-TNF. This effect was time and concentration dependent, as determined by the colony assay, ³H-thymidine uptake assay, and ⁵¹Cr-release assay. ³H-thymidine and ³H-uridine uptake per cell of clone A exposed to rH-TNF was not decreased. This suggests that the mechanisms of the antitumor effect of rH-TNF were not due to inhibition of DNA and RNA synthesis of tumor cells. In vivo growth and lymph node metastases of clone A inoculated i.p. to Donryu strain rats were completely suppressed by 14 consecutive i.p. injections of 10⁵ or 10⁶ U/kg per day of rH-TNF. On the other hand the growth of clone G was not influenced by rH-TNF administration.     

中药灵香草及其混淆品种的比较鉴别

本文比较了中药灵香草Lysimachia foenum-graecum Hance及其混淆品种垂花香草Lysimaehia nutantiflora Chen et C.M.Hu的植物形态、药材性状以及茎、叶组织显微特征。指出垂花香草无灵香草特有的芳香。也无药用记载。应仔细区别,不宜混用。     

Combined second and third toe transfer

Historically, restoration of hand function following multiple digital amputation has been unsatisfactory. The evolution of digital reconstruction with toe transfer has enabled surgeons to reestablish prehension in these severely injured hands. A 4-year experience with 26 consecutive combined second and third toe transfers to replace missing adjacent fingers was reviewed in order to delineate the indications and technical considerations and to emphasize prevention of donor-site complications. Combined second and third toe transfer is reserved for adjacent finger amputations proximal to the digital web space with remaining fingers no longer than the small finger. Radial amputations are replaced with contralateral combined toe units, while ipsilateral toes are more ideal for ulnar amputations. Limited dorsal and plantar skin flaps extending only to the midpoint of the first and third digital web spaces allow for direct donor-site closure and uncomplicated healing. Maintenance of the plantar metatarsal arch by avoiding metatarsal shaft osteotomies or bone grafting-shortened metatarsals eliminates potential gait disturbances. When properly applied in selected patients, this single-stage microsurgical procedure can restore prehensile function, improve the appearance of the hand with multiple digital amputations, and preserve near-normal donor-foot function.     

Groin flap design and versatility

The groin flap is a reliable and well-established reconstructive option for pedicled or free-tissue transfer. Concern regarding its variable vascular origin and caliber has limited its use. To overcome this, a simplified guideline based on the transverse diameter of the patient's index and long fingers at the distal interphalangeal level has been developed. Thus "rule of two finger widths" positions the origin of the vascular pedicle from the femoral vessels two finger widths below the inguinal ligament, the upper flap border two finger widths above the inguinal ligament, the lower flap border two finger widths below the vascular origin, and both parallel to the flap axis, which lies along a line from the vascular origin to the anterosuperior iliac spine. This new groin flap design provides the necessary guidelines for vascular identification, accommodates pediatric and adult stature, and ensures primary donor-site closure if flap dimensions are within the prescribed boundaries. In addition, a new sartorius-cutaneous groin flap is presented. This combines the cutaneous groin flap with the proximal sartorius muscle (up to 15 cm), which is supplied by the deep vessels of the superficial circumflex iliac system. The sartorius-cutaneous groin flap further emphasizes the concept of single-pedicle compound or combined flaps and additionally enhances the extensive reconstructive versatility of previously described groin flaps. Over 200 pedicled and free groin flaps have been performed according to the "rule of two finger widths" over the past 5 years. There have been no complications related to flap design, such as difficulty with flap elevation, marginal necrosis, or donor-site closure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrostatic and steric control of electron self-exchange in cytochromes c, c551, and b5.

The ionic strength dependence of the electron self-exchange rate constants of cytochromes c, c551, and b5 has been analyzed in terms of a monopole-dipole formalism (van Leeuwen, J.W. 1983. Biochim. Biophys. Acta. 743:408-421). The dipole moments of the reduced and oxidized forms of Ps. aeruginosa cytochrome c551 are 190 and 210 D, respectively (calculated from the crystal structure). The projections of these on the vector from the center of mass through the exposed heme edge are 120 and 150 D. For cytochrome b5, the dipole moments calculated from the crystal structure are 500 and 460 D for the reduced and oxidized protein; the projections of these dipole moments through the exposed heme edge are -330 and -280 D. A fit of the ionic strength dependence of the electron self-exchange rate constants gives -280 (reduced) and -250 (oxidized) D for the center of mass to heme edge vector. The self-exchange rate constants extrapolated to infinite ionic strength of cytochrome c, c551, and b5 are 5.1 x 10(5), 2 x 10(7), and 3.7 x 10(5) M-1 s-1, respectively. The extension of the monopole-dipole approach to other cytochrome-cytochrome electron transfer reactions is discussed. The control of electron transfer by the size and shape of the protein is investigated using a model which accounts for the distance of the heme from each of the surface atoms of the protein. These calculations indicate that the difference between the electrostatically corrected self-exchange rate constants of cytochromes c and c551 is due only in part to the different sizes and heme exposures of the two proteins.