Studies on carcinogenesis of human prostate. III. Long-term explant culture of normal prostate and benign prostatic hyperplasia: transmission and scanning electron microscopy.

Ultrastructural changes in normal human prostate and benign prostatic hyperplasia (BPH) during long-term explant culture were compared. Explants of normal prostate obtained at immediate autopsy of young adults of BPH obtained at the time of surgery were maintained as long as 24 weeks in vitro. Ultrastructural changes occurring in epithelial cells during culture were monitored by transmission and scanning electron microscopy. Essentially identical results were found for normal prostate and BPH. During the first week of culture, secretory epithelial cells degenerated and sloughed into the acinar lumen, resulting in an accumulation of necrotic debris. During this period, however, epithelial cells with ultrastructural characteristics of basal cells remained viable, repopulated glandular structures, migrated from glands and ducts, and epithelialized adjacent cut surfaces, eventually covering the explant. On explant surfaces, these basal cells initially were squamous-like, but they later became typically cuboidal, polygonal, or sometimes columnar and formed an epithelium, two cells or more thick. Epithelium with similar features lined acini within explants. Epithelial cells at the surface or within explants were distinguished by the presence of microvilli, junctional complexes, multiple Golgi complexes, well-developed rough endoplasmic reticulum, polyribosomes, nuclei with prominent nucleoli, orthodox mitochondria, scattered tonofilaments, and a basal lamina. Some epithelial cells extended from the lumen to the basal lamina; others were oriented along the basal lamina and did not extend to the lumen. By 1--2 weeks in vitro, these epithelial cells began synthesis of mucus-like material. At later intervals of culture, microvilli were shortened and mucosubstances were reduced. During culture, the stroma became progressively hypocellular and necrotic. In summary, explant-cultured epithelial cells of normal human prostate or BPH were similar ultrastructurally and were found to originate from basal cells, which alone survive culture conditions.

Adenocarcinoma of the kidney. IV. Electron microscopic study of the development of renal adenocarcinomas induced in rats by N-(4'-fluoro-4-biphenylyl)acetamide.

Ultrastructural features of various stages in the histogenesis of renal adenocarcinoma induced in F344 rats by the carcinogen N-(4'-fluoro-4-biphenylyl)acetamide (FBPA) are described. FBPA was added to the diet up to 48 weeks; animals were killed at intervals from 4 to 52 weeks. Characterized were foci of cellular alterations followed by foci of proliferation with dysplasia leading to solid and cystic lesions, carcinoma in situ, and finally, carcinoma. Other lesions included foam cell nodules. Alterations also were noted in distal tubules. By electron microscopy, subtle changes in some proximal tubule cells of the pars recta were noted by 4 weeks (foci of cellular alteration). By 12 weeks there was evidence of dedifferentiation and reduction of cell polarity, thickening of basal lamina, alterations in endoplasmic reticulum and mitochondria, and increases in residual bodies. Nuclei of these cells possessed large nucleoli. From 24 to 36 weeks foci of proliferation were seen and consisted of tumor cells arranged in solid and cystic configurations. In solid lesions (less than 3 mm), in addition to the above alterations, cells showed a microvillus brush border in unusual locations, small and irregular mitochondria, multiple Golgi complexes and basal lamina, and loss of cell polarity. From 36 to 52 weeks carcinoma in situ consisted of cells similar to tumor cells described above. In addition, intracellular canaliculi were present. Areas of tumor cell degeneration and necrosis also were seen. Cells of larger carcinomas (greater than 3 mm), also observed at this interval, were identical to those of carcinoma in situ. Calcification of necrotic debris was noted.

Adenocarcinoma of the kidney. II. Enzyme histochemistry of renal adenocarcinomas induced in rats by N-(4'-fluoro-4-biphenylyl)acetamide.

Activities of a broad spectrum of enzymes were studied histochemically in renal adenocarcinomas induced in young male F344 rats by chronic dietary administration of the carcinogen N(4'-fluoro-4-biphenylyl)acetamide. Enzymes included were: dehydrogenases of glucose-6-phosphate, lactate, succinate, malate, and alpha-glycerophosphate; peroxidase (catalase); glucose-6-phosphatase; alkaline and acid phosphatase; Mg2+ ATPase; 5'-nucleotidase; and aminopeptidase. Levels of enzyme activity were estimated visually and scored from 0 (not detectable) to a maximum of 5 (intense). Comparison of estimated activity for each enzyme was made between small neoplastic nodules (stage III tumors) and large adenocarcinomas (stage IV tumors) and between tumors and portions of normal proximal tubules in parenchyma of kidneys from untreated control rats. The results, which revealed nearly identical levels of activity for most enzymes in both stages III and IV tumors, suggested similar metabolic and biologic behavior of these lesions. However, when data for tumors were compared with data for normal proximal tubules, striking differences were observed consistent with: 1) a marked shift of energy metabolism from oxidative to glycolytic production of ATP, with a corresponding reduction in mitochondrial respiration; and 2) simplification of plasma membrane specializations that were possibly associated with a reduction or loss of transport function. These findings were compared with other histochemical, biochemical, and ultrastructural studies of renal adenocarcinomas in rats and man.

N-Methyl-N-nitrosourea and saccharin: effects on epithelium of normal human urinary bladder in vitro.

The effects of N-methyl-N-nitrosourea (MNU) and saccharin on the histology of normal human bladder "urothelium" (i.e., the epithelium of the urinary bladder) were studied in long-term explant cultures. In MNU-treated cultures, a dose response was observed. Single doses of 1-100 micrograms MNU/ml induced atypical focal hyperplasia, which reverted to a single or a double cell layer as seen in controls. Exophytic, papillary-like hyperplastic structures were noted after a single dose of 10 or 100 micrograms MNU/ml. In contrast to single doses, multiple doses (given every 2 wk) of MNU at 5 or 10 micrograms/ml resulted in striking focal proliferation of dysplastic spindle cells in as little as 6 weeks (three doses of MNU). At 0.5% saccharin, urothelium on explant surfaces resembled that of controls, except in one instance in which mild focal hyperplasia persisted. In the presence of saccharin, hyperplasia induced by a single dose of MNU persisted. Following three multiple doses of MNU in the presence of saccharin, spindle cell hyperplasia was induced similar to that seen with multiple doses of MNU alone, although nuclei appeared more pleomorphic and hyperchromatic in the presence of saccharin.

Studies on carcinogenesis of human prostate. II. Long-term explant culture of normal prostate and benign prostatic hyperplasia: light microscopy.

Light microscopic and histochemical changes in normal human prostate and benign prostatic hyperplasia (BPH) during long-term explant culture were characterized. Normal human prostate obtained at immediate autopsy of young adults or BPH obtained at the time of surgery were maintained in explant culture as long as 24 weeks. Morphologic alterations in glandular epithelium and stroma in response to culture conditions were assessed by light microscopy and histochemistry of mucosubstances. The histologic and histochemical responses of normal prostate and BPH to in vitro conditions were essentially identical. Within 1 week, secretory epithelial cells became necrotic and sloughed into acinar lumina. Remaining epithelial cells proliferated, repopulated acinar structures, and migrated onto explant surfaces forming a new well-differentiated epithelium characterized by synthesis and secretion of neutral and acidic mucosubstances. During subsequent periods in vitro, synthesis and secretion of mucosubstances gradually diminished whereas the stroma and deep glandular structures became necrotic. Our observations suggest that cells comprising the new epithelium in cultured explants of normal human prostate and BPH are derived from prostatic basal cells.

Adenocarcinoma of the kidney. III. Histogenesis of renal adenocarcinomas induced in rats by N-(4'-fluoro-4-biphenylyl)acetamide.

The histogenesis of renal adenocarcinoma induced in F344 rats by the carcinogen N-(4'-fluoro-4-biphenylyl)acetamide (FBPA) was described in order to clarify the site of origin of this neoplasm within the nephron. FBPA was added to the diet up to 48 weeks, and the animals were killed at intervals from 4 to 52 weeks after initiation of the carcinogenic diet. As seen by light microscopy, tumors appeared to arise from the pars recta of the proximal tubule in a series of stages progressing from focal hyperplasia with dysplasia to development of small, then large, neoplastic nodules composed of moderately basophilic, closely packed tumor cells arranged in individual aggregates or lobules surrounded by basement membrane-like material. Karyomegaly, cystic lesions, foam cell lesions, interstitial fibrosis, and casts also accompanied tumorigenesis in this animal model.

Immunocytochemical evaluation of human prostatic carcinomas for carcinoembryonic antigen, nonspecific cross-reacting antigen, beta-chorionic gonadotrophin, and prostate-specific antigen.

The unlabeled antibody peroxidase-antiperoxidase technique was used to examine human malignant prostatic tissue (primary tumors) for the presence of prostate-specific antigen (PSA), carcinoembryonic antigen (CEA), nonspecific cross-reacting antigen (NCA), and beta-chorionic gonadotrophin (HCG). The results were compared to those obtained with normal and hyperplastic prostate tissue (BPH). All specimens of neoplastic, hyperplastic, and normal prostate tissue showed immunostaining reactions for PSA. Immunostaining for PSA was relatively uniform among samples of normal and BPH tissue, but variations with respect to intensity of PSA immunostaining were noted among prostate tumors as well as between the neoplastic cells of individual tumors. Some areas of normal or hyperplastic prostatic epithelium within tumors showed stronger staining reactions for PSA than the tumor cells themselves. Using an antiserum which was able to detect both NCA and CEA, it was found that 16 of 38 tumors (42%) had positive immunostaining reactions. Of these, 15 were subsequently shown to contain only NCA immunoreactivity, and 1 tumor had both NCA and CEA immunoreactivity. NCA, but not CEA, immunoreactivity was identified in hyperplastic prostate tissue within tumor specimens and in BPH specimens. Neither antigen was detected in normal prostatic epithelium. Three of 38 tumors (8%) were found to contain neoplastic cells with HCG immunoreactivity. HCG immunoreactivity was not identified in BPH or normal prostatic tissue. Therefore, HCG and CEA immunoreactivity appear to be tumor-associated antigens in prostate cancer which are expressed with a low incidence. The results of the study identified prostate tumors with different patterns of immunocytochemical markers: 22 of 38 tumors (58%) contained only PSA immunoreactivity; 13 of 38 tumors (34%) contained PSA and NCA immunoreactivity; 2 of 38 tumors (5%) were positive for PSA, NCA, and HCG immunoreactivity; and 1 of 38 tumors (3%) contained PSA, NCA, HCG, and CEA immunoreactivity. Apart from PSA, which was present in all tumors, the markers studied here appeared to be more frequently expressed in well-differentiated tumors than in less-differentiated tumors. Our results suggest the possibility of subclassifying prostate tumors by means of immunocytochemistry.

Aryl hydrocarbon hydroxylase in human prostate.

Aryl hydrocarbon hydroxylase (AHH) was present in explant cultures of human prostate obtained from surgery of benign prostatic hyperplasia and was inducible by benz[a]anthracene (BA). The induction of AHH ranged from 14- to 150-fold when compared with control values and 10-fold variation of AHH inducibility among individuals was observed. Epithelial cells grown from human prostate tissue also contained measurable AHH activity and AHH was inducible by BA and 7,12-dimethylbenz[a]anthracene (DMBA). Inducibility of AHH by BA ranged from 2- to 63-fold. The inducibility of AHH by DMBA was always less than that by BA. In cells treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), there were no changes in AHH activity. These findings support the view that the human prostate is susceptible to environmental polycyclic hydrocarbon carcinogens and that environmental and occupational factors might contribute to the etiology of human prostatic carcinoma.

Ultrastructural studies of regenerating spines of the sea urchin Strongylocentrotus purpuratus. II. Cell types with spherules.

The fine structure of spherulecytes, cell types with large, intracellular membrane-bound vacuoles termed spherules, was investigated in regenerating tips of spines of the sea urchin Strongylocentrotus purpuratus. Two categories of cell types were observed: red spherulecytes and colorless spherulecytes. Red spherulecytes were represented by a single cell type, the eleocyte, while colorless spherulecytes consisted of three morphologically distinct cell types termed morula cells, granulocytes, and vacuolecytes. Eleocytes and morula cells were distributed in both the epidermis and dermis, while granulocytes and vacuolecytes were present only in the dermis. After processing for light and electron microscopy, the spherules of eleocytes typically appeared empty, having lost their content of the red pigment, echinochrome. In contrast, the spherules of morula cell, granulocytes, and vacuolecytes enclosed a variety of granular and other material. The cell types reported in this paper resembled, to various degrees, spherulecytes in the coelomic fluid of echinoids described by other investigators.

Ultrastructural studies of regenerating spines of the sea urchin Strongylocentrotus purpuratus. I. Cell types without spherules.

The fine structure of regenerating tips of spines of the sea urchin Strongylocentrotus purpuratus was investigated. Each conical tip consisted of an inner dermis, which deposits and contains the calcite skeleton, and an external layer of epidermis. Although cell types termed spherulecytes containing large, intracellular membrane bound spherules were also present in spine tissues, only epidermal and dermal cell types lacking such spherules are described in this paper. The epidermis was composed largely of free cells representing several functional types. Over the apical portion of the tip these cells occurred in groups, while proximally they were distributed within longitudinal grooves present along the periphery of the spine from the base to the tip. The terminal portions of apical processes extending from some of the epidermal cells formed a thin, contiguous outer layer consisting of small individual islands of cytoplasm bearing microvilli. Adjacent islands were connected around the periphery by a junctional complex extending roughly 200 A in depth in which the opposing plasma membranes were separated by a narrow gap about 145 A in width bridged by amorphous material. Other epidermal cells were closely associated with the basal lamina, which was 900 A in thickness and delineated the dermoepidermal junction; some of these cells appeared to synthesize the lamina, while others may be sensory nerve cells. The dermis at the spine tip also consisted of several functional types of free cells; the most interesting of these was the calcoblast, which deposits the skeleton. Calcoblasts extended a thin, cytoplasmic skeletal sheath which surrounded the tips and adjacent proximal portions of each of the longitudinally oriented microspines comprising the regenerating skeleton, and distally, formed a conical extracellular channel ahead of the mineralizing tip. The intimate relationship between calcoblasts and the growing mineral surface strongly suggests that these cells directly control both the kinetics of mineral deposition and morphogenesis of the skeleton. Other cell types in the dermis were precalcoblasts and phagocytes. Precalcoblasts may function as fibroblasts and are possible precursors of calcoblasts. Closely associated with the basal lamina at the dermoepidermal junction were extracellular unbanded anchoring fi0rils 150 A to 200 A51 in diameter. Scattered proximally among dermal cells were other extracellular fibrils, presumably collagenous, about 300 A in diameter wit

Histomorphometry and cell kinetics of normal human bladder mucosa in vitro.

In this study, we have quantified the morphologic and kinetic parameters of explant cultured normal adult human urinary bladder mucosa. Quantitative parameters studied were urothelial height, cell density, labelling index and mitotic index. For these studies, urinary bladders from seven adults with no previous history of urologic disease were obtained at autopsy. Mucosal explants were maintained in rocking culture on Gelfoam rafts for up to 33 days using supplemented CMRL 1066 medium. Prior to sampling, cultures were treated with tritiated thymidine and colchicine to investigate tissue kinetics. Data was based on histologic autoradiograms. During culture, urothelial cells retained normal polarity. During the first week of culture, urothelial height increased and cell density decreased. DNA synthesis and mitotic activity occurred primarily among basal cells. DNA synthesis was first noted on day 2 of culture; mitotic activity began after 3 days of culture. Morphologically, human urothelium was well maintained; DNA synthesis and mitotic activity was variable but continued throughout culture.

Studies on carcinogenesis of human prostate. IV. Comparison of normal and neoplastic prostate during long-term explant culture.

Morphologic responses of neoplastic human prostate to long-term explant culture were monitored at serial intervals by LM, TEM and SEM, and compared to normal prostate. Explants were cultured at 37 degrees C in CMRL-1066 supplemented with fetal calf serum and antibiotics. At 0-time culture, normal prostate of young adult males obtained at immediate autopsy, consisted of glandular spaces and ducts lined by columnar to cuboidal secretory epithelial cells and basal cells embedded in fibromuscular stroma. Neoplastic tissue was obtained surgically by transurethral resection (TUR), and consisted of stroma widely infiltrated by well-to moderately-differentiated tumor cells arranged in variable sized, gland-like structures. Secretory activity was evident; basal cells were absent in these glands. During early periods of culture up to several weeks, secretory cells of normal prostate became necrotic. Basal cells remained viable, repopulated acinar structures and epithelialized explant surfaces. At these sites, basal cells, or their derivatives, formed a multicellular epithelium. Exaggerated intercellular spaces separated cells, and synthesis of mucus-like material was seen. Epithelial characteristics included microvilli, junctional complexes, and basal lamina. In marked contrast, tumor cells covered explant surfaces forming an irregular, disorganized layer of squamous-like cells with elongated nuclei and prominent nucleoli. Microvilli, junctional complexes, and basal lamina were poorly developed or absent. Intercellular attachments appeared tenous. Some tumor cells accumulated lipid; synthesis of mucus-like material was not seen. At later intervals of culture up to 10 weeks, synthesis of mucus-like material by basal cells, or their derivatives, declined. Surface cells of neoplastic prostate gradually became more anaplastic in appearance; cells contacted neighboring cells with pseudopodia and filopodia.

Isolation and primary culture of urothelial cells from normal human bladder.

Trypsinization (WT) was employed to disaggregate urothelial cells from normal human urinary bladder mucosa for the preparation of primary cultures. Urinary bladders of two male adults both 25 years old were obtained autopsy 1-2 h after death. The mucosa was incubated in HBSS containing 0.25% trypsin at 37 degrees C. Mean cell yield, viability, and attachment were 14.6 X 10(7), 76%, and 42.5% after WT. In histologic sections of treated mucosa, most of the urothelium was removed by WT. Following plating and attachment, cells obtained by WT formed a monolayer of flattened epithelial-like cells. When stained with polyclonal antikeratin antibody using the indirect immunoperoxidase technique, all of the cells were immunoreactive indicating an epithelial origin. In conclusion, based on morphology and immunocytochemistry, WT removed virtually all of the urothelial cells from the mucosa and no contamination by mesenchymal cells resulted from this procedure. Thus, WT is an appropriate technique for the isolation of urothelial cells and initiation of primary cultures of normal human urothelial cells for subsequent study.

Cell surface changes in preneoplastic and neoplastic epithelium.

Reviewed are studies on alterations of the plasma membrane of neoplastic epithelial cells. Changes in the plasma membrane are probably of unique importance in the major clinical manifestations of cancer. Discussed are sequences in cell membrane changes in vivo and in vitro in both human tumors and chemical-induced animal models of carcinogenesis. Emphasis is placed on alterations in specializations of the plasma membrane, including cell junctions, antigenic and enzyme markers, intramembranous components, ion regulation, and the cytoskeleton. In general, the plasma membrane of neoplastic cells is less specialized than the cell of origin. In mammalian bladder, pleomorphis microvilli may occur concomitant with neoplastic transformation. Cell junctions in tumor cells may be reduced in number of functional characteristics compared to normal cells, which may affect cell-cell communication. Such alterations may be related to tumor cell invasion and metastasis. Normal membrane antigens may be lost or new ones gained in neoplasia. Thus, ABO blood group antigens may be lost in the case of human bronchus and bladder, while carcinoembryonic antigen occurs de novo in tumors of the colon and lung. Similarly, several marker enzymes may be reduced in activity, or appear de novo. Alterations in the number and pattern of distribution of intramembranous particles have been observed in bladder tumors, possibly related to changes in membrane function. Shifts in ion ratios (Na+/K+/Ca++) within neoplastic cells may result in abnormalities in cell shape, cell movement, and cell-cell communication. Many of these changes may reflect defects in function of the Golgi apparatus, which synthesizes components of the plasma membrane. Alterations in one or more components of the cytoskeleton may adversely affect cell shape, mobility of membrane proteins, cell-cell adhesion, etc., and play a major role in malignant cell behavior.

Immunohistochemistry of the cytoskeleton of human prostatic epithelium. Evidence for disturbed organization in neoplasia.

An indirect immunoperoxidase technique was used to evaluate keratin, actin, tubulin, and calmodulin immunoreactivity in histologic sections of normal, hyperplastic, and neoplastic human prostate. Polyclonal as well as monoclonal keratin antibodies produced equivalent and intense staining of normal epithelium. The immunoreactivity of normal prostate with keratin antibodies was more pronounced than with antibodies to the other components of the cytoskeleton. Variation in staining for components of the cytoskeleton was minimal. The same findings applied to hyperplastic prostate. The immunoreactivity of prostate tumors with antibodies to these cytoskeletal proteins differed markedly from normal prostate. Prostatic carcinomas showed reduced keratin immunoreactivity with a panepithelial antibody, but unaltered or enhanced immunoreactivity with tubulin, actin, and calmodulin antibodies. Many tumors were unreactive with a monoclonal keratin antibody that was strongly reactive with tissues that contained cytokeratin 18 (45-kd) and which intensely stained normal and hyperplastic prostate. In addition, prostate carcinomas often yielded heterogeneous patterns of staining with actin, tubulin, and calmodulin antibodies in contrast to normal and hyperplastic prostate, which showed uniform staining. The results suggest that a disturbance in the organization of the cytoskeleton may accompany neoplastic transformation of human prostate.

Correlation of cytokeratin patterns with histopathology during neoplastic progression in the rat urinary bladder.

The discrimination of atypical (premalignant) cells from invasive neoplastic cells in primary bladder lesions is a major diagnostic problem in cytopathology and surgical pathology. We have used an animal model of urinary bladder carcinogenesis to determine the specific changes which occur in the expression of certain cytokeratins (CK) during the progression of lesions from regenerative hyperplasia and carcinoma in situ to transitional cell carcinomas. At sequential time points following exposure of the rat bladder epithelium to N-methyl-N-nitrosourea in vivo, immunohistochemical staining of CKs was evaluated in ethanol-fixed samples from the induced urothelial lesions using commercially available anti-CK mouse monoclonal antibodies. Specific changes were found in the expression of CKs 13, 18, and 19 during the neoplastic progression of induced urothelial lesions in the rat. These changes included the reciprocal loss of expression of CK 19 and the reappearance of CK 18 as malignant tumors developed. Invasive cells also did not express CK 13. Our results, based on the rat model, are similar to those reported by others on CK expression in human bladder tumors. Because these changes in CK expression occurred at specific points in the progression of urothelial lesions, the antibodies utilized in this study may be helpful in predicting the invasive potential of cells present in cytopathological specimens and tissue biopsies from human urothelial lesions.

Causes and costs of injuries in multiple trauma patients requiring extrication from motor vehicle crashes.

Prospective and contemporaneous medical and economic cost studies of 144 victims of motor vehicle crashes admitted to a regional level I trauma center with multiple injuries (ISS > or = 16) revealed 122 non-ejected patients, of whom 102 required extrication (EXTRIC) from the vehicle for physical or medical reasons and 20 who did not (N group). There were no differences in age (EXTRIC, 34 +/- 17 years; N, 41 +/- 24 years), type of crash (Frontal: 57% EXTRIC, 60% N; Lateral: 32% EXTRIC, 35% N) restraint use (35% EXTRIC, 35% N), or mortality (29% EXTRIC, 30% N). However, the estimated maximum speed before the crash was higher in EXTRIC patients (50 +/- 16 mph vs. 46 +/- 18 mph N, p < 0.04), as was the change in velocity (delta V) on impact (EXTRIC 30 +/- 15 mph; N, 24 +/- 8 mph, p < 0.01). Brain injuries (51% EXTRIC vs. 35% N) and lower extremity injuries were more numerous in EXTRIC patients (59% vs. 20% N, p < 0.003) and the number of splenic, lower extremity, and pelvic injuries associated with shock was greater in EXTRIC patients, p < 0.02; as were postinjury complications. As a result, operating room costs from orthopedic and plastic surgery increased professional charges in the EXTRIC group versus the N group ($20,000, EXTRIC; $17,000, N) and critical care costs ($13,000, EXTRIC; $4,000, N) with total costs of $72,000 and $77,000, respectively. The lower extremity injuries in EXTRIC patients were primarily a result of body part contacts with intrusions (CIs) of the car occupant compartment structures [73% with vs. 24% without (p < 0.0001)]. In lateral MVCs, brain injuries were also more commonly associated with CIs of the side window frame or A pillar (72% CI vs. 25% no CI; p < 0.035); but as a whole in MVCs in which extrication was necessary, lower extremity injuries from instrument panel or toepan CIs appeared more frequent than those resulting from contacts only (p < 0.0001). In EXTRIC patients, 69% of those in shock had CI injuries, and 80% of the deaths in the EXTRIC group were associated with CI injury. These data suggest that measures designed to prevent CIs by strengthening car passenger compartment structures may reduce the incidence of severe brain and lower extremity injuries and may reduce the need for extrication after MVCs.