Kelly, Patrick J.

Puppies in the second half of their growing period have been observed for one and a half to four and a half months after creation of a superficial femoral arteriovenous fistula on the right side. From measurements of the whole bone and from microradiographic and tetracycline-fluorophore studies of the diaphysial bone, it is believed that the following statistically significant phenomena may be attributed to the influence of the arteriovenous fistula. 1. All bones distal to the fistula are influenced in their growth. The tibia and metatarsals become heavier and larger, but retain normal shape. Although stimulation of longitudinal growth is small, it is significant for the tibiae and nearly significant for the femora in these short-term experiments. 2. The histological structure of the bones remains normal but quantitative changes are induced. The compact bone is more porous because of an increased number of osteones. Haversian turnover itself is affected in that the individual formation time of osteones tends to become longer, especially in the metatarsals. 3. Periosteal new bone formation is immediately stimulated, producing a flare of new bone. This accounts for the increase in diaphysial weight in the tibia but not in the metatarsals, where the same effect results from decreased resorption of old bone. 4. Endosteal new bone formation is depressed, especially in the metatarsals, resulting in an enlarged medullary cavity.

The effects of alterations in serum calcium levels on the volume of distribution of a calcium tracer in bone and on bone blood flow were investigated in dogs by manipulation of parathyroid status. The volume of distribution increases with increasing serum calcium. This implies that there is a concentration-dependent binding mechanism in the extravascular space of bone, which is not saturated at the levels of serum calcium achieved in these experiments. The skeletal exchangeable calcium was increased in hypercalcemic dogs and decreased in hypocalcemic dogs. Cancellous bone contains proportionately more exchangeable calcium than cortical bone. Bone blood flow was decreased by 50% 15 min after injection of a bolus of parathyroid hormone (PTH) but returned to control values by 240 min. Fifty-two hours after the induction of hypercalcemia with repeated doses of PTH, there was no difference in blood flow over control animals.

The variable of age was used to study macromolecules in bone that may mediate in part the in vivo readily exchangeable calcium-binding capacity (VCa2+D). Organic components were extracted from nonmineralized bone with 4 M guanidine-HCl and from both nonmineralized and mineralized bone with 0.1 M EDTA. The composition of pup bone extracts demonstrated an enrichment in protein, hexuronate, sialic acid, organic phosphorus, and bound sulfate when compared with other age groups. In vitro calcium-binding studies identified low-affinity (Kd congruent to 10(-3) M) sites in both types of extracts; high-affinity sites (Kd congruent to 10(-5) M) were only evident in EDTA extracts of bone. Readily exchangeable calcium-binding capacity in vivo was found to decrease from pup (40.7 mM) to adolescent (11.1 mM) to the mature/old groups (2.6/1.2 mM); however, a large difference in low-affinity site number was only observed between pup and adolescent bone extracts. The overall organic composition of EDTA and guanidine-HCl extracts generally reflected the composition of total bone, which dropped dramatically on a dry weight basis from pup to adolescent groups. A similar pattern was observed with the number of low-affinity binding sites measured in vitro. In vitro binding data indicate that nonmineralized matrix of pup bone, extractable by 4 M guanidine-HCl, possesses enough capacity to accommodate approximately 40% of the readily exchangeable pool. As age progresses, other components of the blood-bone exchange process, such as vascularity, may reduce the readily exchangeable calcium pool size below the amount of low-affinity sites measured in vitro.

The penetrations of methicillin, oxacillin, and cephalothin into cortical bone and synovial tissues were studied 1 h after their intravenous administration in 105 patients having arthroplasty of the hip. Although the lowest serum levels were noted with cephalothin ( P < 0.01), more patients receiving cephalothin achieved osseous drug levels inhibitory to staphylococci ( P < 0.01). Differences in the penetration of the three agents into synovial tissues were not statistically significant.

Abstract Thirty patients with histologically confirmed posterior fossa ependymomas operated on between January 1976 and December 1988 were reviewed. The median age was 44 years (range, 1-69 yr). There were 7 children (aged 5 yr or younger) and 23 adults (aged 16 yr or older). There were 18 female patients and 12 male patients. Headache, nausea and vomiting, and disequilibrium were the most frequent symptoms. The most common findings were ataxia and nystagmus. Gross total resection was performed in 8 patients (27%), subtotal resection in 21 patients (70%), and biopsy in only 1 patient (3%), Tumors were low grade in 73% and high grade in 27%. Twenty-seven patients underwent posterior fossa radiotherapy (median dose, 5400 cGy). Fourteen patients also underwent spinal irradiation (median dose, 3520 cGy). Age was the only significant prognostic factor identified (P &lt;0.01). The 5-year survival rates were 76% for adults and 14% for children. All 14 patients who died had recurrent or residual tumor at the primary site. This review suggests that in patients with primary posterior fossa ependymomas the following is true: 1) the young patient (5 yr old or younger) has a poor prognosis: 2) there was a trend toward a better 5-year survival rate with a gross total resection; 3) if recurrence occurs, it will be at the primary intracranial site; and 4) symptomatic spinal seeding does not occur frequently.

Os linfomas primários do SNC são raros, mas sua incidência tem aumentado nos últimos anos, Estes tumores frequentemente se localizam nos gânglios da base e tálamo ou se apresentam de forma multifocal. O tratamento atual para eles é a radioterapia, associada ou não a quimioterapia. Devido à sua extremamente baixa morbidade, a biópsia estereo-táxica é o método ideal para determinar o diagnóstico histológico em pacientes com suspeita de linfomas do SNC. Os autores apresentam estudo de 49 casos de linfomas primários do SNC, diagnosticado por biópsia estereotáxica.