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Biomedical subjects

M A Suckow

Publications and source records attributed to M A Suckow.

27 records · Page 2Linked to original sources

Pharmacological studies of centrifugation-induced analgesia.

Subjecting rats to a brief period of centrifugal rotation produces a brief analgesia (1-2 min) that is similar to that produced by pretreatment with morphine. The effect of the morphine is blocked by naloxone, while that of the centrifugal rotation is only partially blocked by the same dose of naloxone. Cholinergic blocking agents such as scopolamine are also capable of partially blocking the rotational-induced analgesia. The combination of pretreatment with scopolamine plus naloxone is capable of completely blocking the rotational-induced analgesia, suggesting the involvement of both central cholinergic and endogenous opioid components.

Analgesia↗

Heat-labile toxin-producing isolates of Pasteurella multocida from rabbits.

Five of one hundred forty seven isolates of Pasteurella multocida from rabbits were found to produce heat-labile toxin. Each isolate was assayed for the ability of potassium thiocyanate (KSCN) extracts to cause dermonecrosis in guinea pig skin, ability of bacteria or filtrates to cause cytotoxicity in cell cultures, and reactivity with monoclonal antibodies to heat-labile P. multocida toxin. Five capsular type D isolates produced dermonecrosis and reacted with monoclonal antibodies to toxin. Filtrates of all five of these isolates were cytotoxic for cell cultures. Potassium thiocyanate extracts of all five isolates caused pleuritis and pneumonia in rabbits after intranasal inoculation. Turbinate atrophy was seen in 5 of 19 rabbits inoculated intranasally with toxic extracts. Heat-labile toxin was not produced by 109 capsular type A isolates or 19 nontypable isolates.

Administration, Intranasal↗

Cryptosporidiosis in guinea pigs: an animal model.

Cryptosporidia from natural cryptosporidiosis in guinea pigs were experimentally transmitted to both adult and juvenile guinea pigs. Cryptosporidia were associated with the villi of the ileum, jejunum, and duodenum. Both juveniles and adults were equally susceptible to cryptosporidia, as determined by decreases in villus height, increases in crypt depth, and decreases in villus height/crypt depth ratios, when compared with uninoculated animals. When multiple paired comparisons were made between 2 and 10 days postinoculation, there were significant decreases in villus height/crypt depth ratios with time. A dose study showed that 6-week-old guinea pigs were all infected with doses as low as 325 oocysts per animal. When sampled at weekly intervals postinoculation, guinea pigs had significant evidence of infection up to 2 weeks but had recovered completely by 4 weeks. Guinea pigs mounted a specific humoral immune response against cryptosporidia, as measured by an immunoperoxidase technique. Guinea pigs challenged by reinoculation with cryptosporidial oocysts were completely refractory to reinfection. These studies show that cryptosporidiosis in guinea pigs is a useful small animal model of this disease.

Age Factors↗

In vivo absorption of aluminium-containing vaccine adjuvants using 26Al.

Aluminium hydroxide (AH) and aluminium phosphate (AP) adjuvants, labelled with 26Al, were injected intramuscularly (i.m.) in New Zealand White rabbits. Blood and urine samples were collected for 28 days and analysed for 26Al using accelerator mass spectrometry to determine the absorption and elimination of AH and AP adjuvants. 26Al was present in the first blood sample (1 h) for both adjuvants. The area under the blood level curve for 28 days indicates that three times more aluminium was absorbed from AP adjuvant than AH adjuvant. The distribution profile of aluminium to tissues was the same for both adjuvants (kidney > spleen > liver > heart > lymph node > brain). This study has demonstrated that in vivo mechanisms are available to eliminate aluminium-containing adjuvants after i.m. administration. In addition, the pharmacokinetic profiles of AH and AP adjuvants are different.

Absorption↗

Enhanced bone regeneration using porcine small intestinal submucosa.

Small intestinal submucosa (SIS) is an easily produced material that has been used experimentally for tissue engineering. To evaluate the ability of SIS to facilitate bone growth within a long-bone defect, a segment of the radius was surgically removed in adult, female Sprague-Dawley rats. The defect was either left unfilled or implanted with SIS, demineralized cortical bone (DMCB), or ovalbumin. The defect was evaluated radiographically and histologically after 3, 6, 12, and 24 weeks. Tissue remodeling within the defect was evident by week 3 in SIS- and DMCB-treated rats. Filling was characterized initially by infiltration of mononuclear cells and extracellular material in SIS-implanted rats and multifocal remodeling bone particles and cartilage formation in DMCB-implanted rats. Cartilage was observed as early as 3 weeks and bone as early as 6 weeks in SIS-implanted rats. Filling of the defect arose from multiple foci in DMCB-implanted rats, but was contiguous with and parallel to the ulnar shaft in SIS-implanted rats, suggesting that defect repair by SIS may be conductive rather than inductive. Rats in which the defect was left unfilled demonstrated slow but progressive filling of the defect, characterized by mononuclear cell infiltrates and fibrous extracellular material. In summary, SIS facilitated rapid filling of a long-bone defect. These results suggest that SIS may be useful as a bone repair material.

Animals↗

Comparison of the host ranges and antigenicity of Cryptosporidium parvum and Cryptosporidium wrairi from guinea pigs.

Oocysts of a Cryptosporidium isolate from guinea pigs were not infectious for adult mice, but were infectious for two of three newborn calves and for suckling mice. However, oocysts isolated from calves or mice infected with guinea pig Cryptosporidium were not infectious for guinea pigs. Four isolates of C. parvum from calves were incapable of infecting weanling guinea pigs. Microscopic examination of tissue from the colon and cecum of suckling guinea pigs inoculated with C. parvum revealed sparse infection of some pups. These host range studies and previously described differences in 125I-labeled oocyst surface protein profiles between Cryptosporidium sp. from guinea pigs and C. parvum suggest they are distinct species. We propose the name Cryptosporidium wrairi be retained. Studies with monoclonal antibodies indicate that C. wrairi and C. parvum are antigenically related.

Animals↗

Effect of hyperimmune bovine colostrum raised against Cryptosporidium parvum on infection of guinea pigs by Cryptosporidium wrairi.

Oocysts shedding was markedly reduced in guinea pigs inoculated intraintestinally with Cryptosporidium wrairi sporozoites that had been incubated with hyperimmune bovine colostrum raised to C. parvum when compared with shedding in guinea pigs inoculated with sporozoites incubated in either non-immune bovine colostrum or buffered saline. However oocyst shedding was apparently not reduced in guinea pigs inoculated by gavage with oocysts of C. wrairi and subsequently treated twice daily per os with hyperimmune bovine colostrum. Similarly, oocyst shedding was apparently not reduced by oral treatment with hyperimmune bovine colostrum when treatment was begun simultaneously with inoculation of C. wrairi oocysts.

Animals↗

Microsphere uptake by the intestine of White Leghorn chickens.

A study was conducted to determine the effective size for latex microsphere uptake in the intestine of white leghorn chickens. Three trials were conducted in which ligated intestinal segments of anesthetized 8-wk-old chickens were injected with 0.2-, 0.5-, 2-, 6-, 10-, or 20-mu diameter fluoresceinated latex microspheres. Microspheres were counted in brush border, epithelium, and lamina propria of each intestinal segment, liver, and spleen. After 1 hr, the 0.2-, 0.5-, and 2-mu microspheres were oriented along the brush border of epithelial cells and microsphere uptake into the epithelium and lamina propria was observed in the duodenum, ileum, cecum, cecal tonsil, and colon. Uptake of microspheres of 6, 10, and 20 mu diameter into epithelium and lamina propria was not observed in any intestinal segment. Also, no microspheres of any diameter were observed in sections of liver and spleen to suggest that there was no appreciable entry of microspheres into the bloodstream within 1 hr after administration. The results indicated that uptake of microspheres by the chicken intestine is a size-dependent process with microspheres < or = 2 mu being taken up to an equal extent by most segments of intestine.

Animals↗